WORKSHOP TECHNOLOGY & MANUFACTURING PROCESSES

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Author

SHAILENDRA KUMAR VERMA

DISCLAIMER

THIS BOOK HAS BEEN PREPARED FOR EDUCATIONAL, ACADEMIC AND COMPETITIVE-EXAMINATION PREPARATION PURPOSES ONLY.

THE INFORMATION, DEFINITIONS, EXPLANATIONS, FORMULAS, EXAMPLES AND PRACTICE QUESTIONS PROVIDED IN THIS BOOK ARE INTENDED TO HELP STUDENTS UNDERSTAND THE FUNDAMENTAL CONCEPTS OF WORKSHOP TECHNOLOGY AND MANUFACTURING PROCESSES.

WHERE PREVIOUS-YEAR QUESTIONS ARE INCLUDED, THE EXAM NAME AND YEAR SHOULD BE TREATED ACCORDING TO THE AVAILABLE SOURCE/REFERENCE.

SOME QUESTIONS REPRODUCED IN PUBLIC EXAM-PREPARATION RESOURCES MAY BE MEMORY-BASED QUESTIONS RATHER THAN QUESTIONS REPRODUCED FROM AN OFFICIALLY RELEASED QUESTION PAPER. SUCH QUESTIONS SHOULD THEREFORE BE IDENTIFIED SEPARATELY AS MEMORY-BASED QUESTIONS.

THIS BOOK IS NOT AN OFFICIAL PUBLICATION OF SSC, RRB, GATE, UPSC/ESE, ANY STATE PUBLIC SERVICE COMMISSION, PSU, ITI, POLYTECHNIC, UNIVERSITY OR ANY OTHER EXAMINATION AUTHORITY.

THE AUTHOR HAS MADE REASONABLE EFFORTS TO PRESENT TECHNICALLY ACCURATE INFORMATION.

HOWEVER, MANUFACTURING TECHNOLOGY IS A BROAD AND CONTINUOUSLY DEVELOPING FIELD AND TERMINOLOGY, STANDARDS, EXAMINATION PATTERNS, AND TECHNICAL PRACTICES MAY VARY AMONG INSTITUTIONS AND EXAMINATION AUTHORITIES.

READERS ARE ADVISED TO VERIFY CRITICAL TECHNICAL INFORMATION, STANDARDS, CODES, EXAMINATION NOTIFICATIONS AND OFFICIAL EXAMINATION INFORMATION FROM THE RELEVANT OFFICIAL AUTHORITIES.

THE AUTHOR AND PUBLISHER SHALL NOT BE RESPONSIBLE FOR ANY LOSS, DAMAGE, ACADEMIC CONSEQUENCE, EXAMINATION CONSEQUENCE OR OTHER LIABILITY ARISING FROM THE USE OR INTERPRETATION OF THE INFORMATION CONTAINED IN THIS BOOK.

COPYRIGHT NOTICE

THIS BOOK IS INTENDED FOR LAWFUL EDUCATIONAL USE. NO PORTION OF THIS PUBLICATION SHOULD BE REPRODUCED, DISTRIBUTED, UPLOADED, RESOLD OR TRANSMITTED IN ANY FORM WITHOUT APPROPRIATE PERMISSION FROM THE COPYRIGHT HOLDER, EXCEPT WHERE PERMITTED UNDER APPLICABLE LAW.
© Shailendra Kumar Verma

PREFACE

WORKSHOP TECHNOLOGY IS ONE OF THE FUNDAMENTAL SUBJECTS FOR STUDENTS AND CANDIDATES PREPARING FOR EXAMINATIONS RELATED TO MECHANICAL ENGINEERING, MANUFACTURING ENGINEERING, PRODUCTION ENGINEERING, ITI, DIPLOMA, SSC JE, RRB JE, GATE, ESE/IES, STATE JE/AE AND PSU EXAMINATIONS.

THE SUBJECT COVERS THE BASIC PRINCIPLES AND PRACTICAL ASPECTS OF MANUFACTURING, INCLUDING CASTING, METAL FORMING, WELDING, MACHINING, MACHINE TOOLS, GRINDING, HEAT TREATMENT, METROLOGY, WORKSHOP TOOLS AND ADVANCED MANUFACTURING PROCESSES.
THIS BOOK HAS BEEN DESIGNED WITH A DUAL PURPOSE:

TO PROVIDE A CLEAR CONCEPTUAL UNDERSTANDING OF WORKSHOP TECHNOLOGY AND MANUFACTURING PROCESSES.

TO PROVIDE A LARGE COLLECTION OF EXAM-ORIENTED QUESTIONS AND PREVIOUS-YEAR/MEMORY-BASED QUESTIONS WITH ANSWERS AND EXPLANATIONS.

THE BOOK BEGINS WITH FUNDAMENTAL DEFINITIONS BECAUSE A STRONG UNDERSTANDING OF TERMINOLOGY MAKES THE ADVANCED TOPICS MUCH EASIER TO UNDERSTAND.

THE SYLLABUS HAS BEEN ORGANIZED PROGRESSIVELY—FROM BASIC WORKSHOP CONCEPTS AND ENGINEERING MATERIALS TO CASTING, FORMING, JOINING, MACHINING, GRINDING, HEAT TREATMENT AND ADVANCED MANUFACTURING PROCESSES. THESE AREAS BROADLY CORRESPOND WITH ESTABLISHED MANUFACTURING-PROCESS CURRICULA.

TABLE OF CONTENTS

PART I — FUNDAMENTALS OF WORKSHOP TECHNOLOGY

Chapter 1 — Fundamental Definitions of Workshop Technology
100 MCQs
Chapter 2 — Engineering Materials
100 MCQs
Chapter 3 — Mechanical Properties of Materials
100 MCQs

PART II — WORKSHOP TOOLS & MEASUREMENT

Chapter 4 — Marking and Measuring Tools
100 MCQs
Chapter 5 — Fitting and Bench Work
100 MCQs
Chapter 6 — Jigs, Fixtures and Gauges
100 MCQs

PART III — FOUNDRY & CASTING TECHNOLOGY

Chapter 7 — Introduction to Foundry and Casting
100 MCQs
Chapter 8 — Patterns and Pattern Allowances
100 MCQs
Chapter 9 — Moulding Sand and Mould Making
100 MCQs
Chapter 10 — Core, Gating and Risering
100 MCQs
Chapter 11 — Casting Processes and Casting Defects
100 MCQs
Chapter 12 — Furnaces and Melting Practice
100 MCQs

PART IV — METAL FORMING PROCESSES

Chapter 13 — Introduction to Metal Forming
100 MCQs
Chapter 14 — Forging
100 MCQs
Chapter 15 — Rolling
100 MCQs
Chapter 16 — Extrusion and Drawing
100 MCQs
Chapter 17 — Sheet Metal Processes
100 MCQs

PART V — WELDING & JOINING

Chapter 18 — Fundamentals of Welding
100 MCQs
Chapter 19 — Gas Welding and Gas Cutting
100 MCQs
Chapter 20 — Arc Welding
100 MCQs
Chapter 21 — Resistance and Special Welding
100 MCQs
Chapter 22 — Brazing, Soldering and Adhesive Joining
100 MCQs
Chapter 23 — Welding Defects and Weldability
100 MCQs

PART VI — MACHINE TOOLS & MACHINING

Chapter 24 — Fundamentals of Machining
100 MCQs
Chapter 25 — Lathe Machine
100 MCQs
Chapter 26 — Lathe Operations
100 MCQs
Chapter 27 — Drilling and Boring Machines
100 MCQs
Chapter 28 — Shaper, Planer and Slotter
100 MCQs
Chapter 29 — Milling Machine
100 MCQs
Chapter 30 — Milling Operations and Indexing
100 MCQs

PART VII — CUTTING TOOLS & MACHINING SCIENCE

Chapter 31 — Cutting Tools and Tool Materials
100 MCQs
Chapter 32 — Chip Formation and Cutting Mechanics
100 MCQs
Chapter 33 — Cutting Fluids, Tool Life and Tool Wear
100 MCQs

PART VIII — GRINDING & FINISHING

Chapter 34 — Grinding Technology
100 MCQs
Chapter 35 — Grinding Wheels
100 MCQs
Chapter 36 — Grinding Operations
100 MCQs
Chapter 37 — Honing, Lapping, Polishing and Superfinishing
100 MCQs

PART IX — HEAT TREATMENT

Chapter 38 — Fundamentals of Heat Treatment
100 MCQs
Chapter 39 — Annealing, Normalizing and Hardening
100 MCQs
Chapter 40 — Tempering and Case Hardening
100 MCQs
Chapter 41 — Fe-C Diagram, TTT and CCT Diagrams
100 MCQs

PART X — ADVANCED MANUFACTURING PROCESSES

Chapter 42 — Non-Traditional Machining
100 MCQs
Chapter 43 — Advanced Casting Processes
100 MCQs
Chapter 44 — Advanced Welding Processes
100 MCQs
Chapter 45 — Advanced Metal Forming Processes
100 MCQs

PART XI — METROLOGY & QUALITY CONTROL

Chapter 46 — Measurement and Metrology
100 MCQs
Chapter 47 — Limits, Fits and Tolerances
100 MCQs
Chapter 48 — Surface Roughness and Inspection
100 MCQs

PART XII — WORKSHOP SAFETY

Chapter 49 — Industrial and Workshop Safety
100 MCQs

PART XIII — EXAM MASTER SERIES

Chapter 50 — Mixed Previous-Year Questions
200+ MCQs
Chapter 51 — Numerical Problems
200+ Questions
Chapter 52 — Most Important One-Liners
500+ Questions
Chapter 53 — Rapid Revision Questions
500+ Questions
Chapter 54 — Full-Length Mock Tests
10 Mock Tests

EXAM-WISE QUESTION BANK

The book will also contain separate question collections, wherever reliable exam attribution is available, for:
SSC JE
RRB JE
GATE
ESE/IES
State JE
State AE
PSU Examinations
ITI Examinations
Diploma/Polytechnic Examinations
Other Technical Examinations

MCQ FORMAT USED IN THIS BOOK

Question
Q1. What is the primary purpose of a workshop?
A. Only to store raw materials
B. To carry out technical and manufacturing activities
C. Only to sell finished products
D. Only to transport materials
Answer: B. To carry out technical and manufacturing activities
Explanation:
A workshop is a designated working environment where manufacturing, machining, fabrication, repair, maintenance, assembly, measurement and other technical activities are performed using appropriate tools, machines and equipment.
Exam Question
Note: This is an original exam-oriented question and is not claimed as a previous-year question.

CHAPTER 1FUNDAMENTAL DEFINITIONS OF WORKSHOP TECHNOLOGY

1.1 Introduction

Workshop Technology is a branch of engineering knowledge concerned with the methods, tools, machines, materials and processes used to manufacture, modify, assemble, inspect and maintain engineering components and products.
A student cannot properly understand advanced manufacturing processes without first understanding basic workshop terminology.
For this reason, this book begins with fundamental definitions.

1.2 Workshop

Definition
A workshop is a designated place where manufacturing, machining, fabrication, repair, maintenance, assembly, inspection and other technical activities are carried out using appropriate tools, machines and equipment.
Examples
Fitting workshop
Machine shop
Welding workshop
Foundry
Carpentry shop
Sheet-metal shop
Exam Point
A workshop is not merely a place containing machines. It is an organized working environment where engineering operations are performed.

1.3 Workshop Technology

Definition
Workshop Technology is the systematic study of materials, tools, machines and manufacturing processes used to convert raw materials into useful engineering products.
Main Areas
Workshop Technology includes:
Fitting
Carpentry
Welding
Foundry
Sheet-metal work
Forging
Machining
Grinding
Measurement
Inspection
Heat treatment

1.4 Manufacturing

Definition
Manufacturing is the process of converting raw materials into useful products or components through physical, chemical, mechanical or other controlled processes.
Example
Steel bar → Cutting → Turning → Drilling → Finishing → Finished component
Exam Point
Manufacturing involves more than material removal. It can include:
Casting
Forming
Joining
Machining
Heat treatment
Surface finishing
Additive manufacturing

1.5 Manufacturing Process

Definition
A manufacturing process is a planned sequence of operations by which raw material is converted into a component or product having the required shape, size, properties and surface quality.
Manufacturing processes are commonly classified into major groups such as:
Casting
Forming
Machining
Joining
Heat treatment
Surface treatment
Additive manufacturing
This broad classification is consistent with the way manufacturing-process curricula organize the subject.

1.6 Production

Definition
Production is the overall activity of creating goods or services by utilizing resources such as materials, machines, labour, energy, information and capital.
Difference
Manufacturing mainly concerns the transformation of materials into products.
Production is a broader concept that includes manufacturing along with planning, material handling, inspection, assembly and other activities.

1.7 Production System

Definition
A production system is an organized arrangement of people, machines, materials, methods and other resources used to produce goods efficiently.
Major Types
Job production
Batch production
Mass production
Continuous production

1.8 Process

Definition
A process is a planned method or sequence of actions through which a desired change is produced in a material, component or product.
Example
Turning is a machining process used to remove material from a rotating workpiece.

1.9 Operation

Definition
An operation is a specific manufacturing activity performed to achieve a particular change in a workpiece.
Example
In manufacturing a shaft:
Facing
Turning
Grooving
Threading
Each can be considered a separate operation.

1.10 Job

Definition
A job is a particular workpiece or manufacturing task assigned to a worker, machine or production system.

1.11 Workpiece

Definition
A workpiece is the piece of material on which a manufacturing operation is performed.
Example
During turning, the metal bar mounted on the lathe is the workpiece.

1.12 Raw Material

Definition
Raw material is the basic material used as an input for manufacturing a product.
Examples
Steel bar
Aluminium sheet
Copper rod
Cast iron casting
Metal plate

1.13 Finished Product

Definition
A finished product is a manufactured item that has completed all required production operations and satisfies the specified requirements.

1.14 Semi-Finished Product

Definition
A semi-finished product is a product that has undergone some manufacturing operations but requires additional processing before becoming a final product.
Examples
Rolled steel plate
Forged blank
Rough casting
Extruded section

1.15 Machine

Definition
A machine is a mechanical, electrical or other device that uses energy to perform useful work.

1.16 Machine Tool

Definition
A machine tool is a power-driven machine used to hold and control a workpiece and/or cutting tool to perform manufacturing operations with controlled movement.
Examples
Lathe
Milling machine
Drilling machine
Shaper
Planer
Grinding machine
Important Point
A machine tool is specifically designed for manufacturing operations.

1.17 Cutting Tool

Definition
A cutting tool is a tool used to remove unwanted material from a workpiece in the form of chips during machining.
Examples
Single-point turning tool
Drill
Milling cutter
Reamer

1.18 Hand Tool

Definition
A hand tool is a tool primarily operated manually without direct power-driven cutting action.
Examples
Hammer
File
Hacksaw
Chisel
Screwdriver
Spanner

1.19 Power Tool

Definition
A power tool is a tool operated using an external power source such as electricity, compressed air or hydraulic power.

1.20 Jig

Definition
A jig is a work-holding and tool-guiding device used to locate and hold a workpiece and guide the cutting tool during an operation.
Key Point
Jig = Holds work + Guides tool

1.21 Fixture

Definition
A fixture is a device used to accurately locate and securely hold a workpiece during a manufacturing operation.
Key Point
Fixture = Holds and locates workpiece
Unlike a jig, a conventional fixture does not normally guide the cutting tool.

1.22 Gauge

Definition
A gauge is a measuring or checking device used to determine whether a dimension or characteristic of a component falls within specified limits.

1.23 Inspection

Definition
Inspection is the process of examining a component or product to determine whether it conforms to specified requirements.

1.24 Measurement

Definition
Measurement is the process of determining the numerical value of a physical quantity by comparison with an accepted standard.

1.25 Accuracy

Definition
Accuracy indicates how close a measured value is to the true or accepted value.
Example
If the actual diameter is 50.00 mm and the measured value is 50.01 mm, the measurement has a small error and is relatively accurate.

1.26 Precision

Definition
Precision indicates the degree of agreement among repeated measurements.
Important Difference
Accuracy → Closeness to true value
Precision → Repeatability/consistency
This distinction is extremely important in technical examinations.

1.27 Tolerance

Definition
Tolerance is the permissible variation in a specified dimension.
For a dimension:
50.00 ± 0.02 mm
the total tolerance is:
0.04 mm

1.28 Allowance

Definition
Allowance is the intentional difference between the dimensions of mating parts designed to obtain a desired fit.
Important Difference
Tolerance = Permissible variation
Allowance = Intentional difference between mating dimensions

1.29 Surface Finish

Definition
Surface finish refers to the quality or texture of a manufactured surface resulting from the manufacturing process.
Surface finish is important for:
Friction
Wear
Sealing
Appearance
Fatigue performance
Proper functioning of mating components

1.30 Machining

Definition
Machining is a manufacturing process in which unwanted material is removed from a workpiece to obtain the required shape, size and surface finish.
Examples
Turning
Milling
Drilling
Shaping
Grinding

1.31 Metal Cutting

Definition
Metal cutting is a material-removal process in which a cutting tool removes unwanted material from a metal workpiece, generally in the form of chips.

1.32 Casting

Definition
Casting is a manufacturing process in which molten material is poured into a mould cavity and allowed to solidify to obtain the desired shape.
Basic Steps
Melting → Pouring → Solidification → Removal → Cleaning/Finishing

1.33 Forming

Definition
Metal forming is a manufacturing process in which a metal workpiece is plastically deformed to obtain the desired shape without significant removal of material.
Examples
Forging
Rolling
Extrusion
Drawing
Sheet-metal forming

1.34 Forging

Definition
Forging is a metal-forming process in which a workpiece is plastically deformed by the application of compressive forces using tools, dies, hammers or presses.

1.35 Rolling

Definition
Rolling is a metal-forming process in which metal is passed between rotating rolls to reduce its thickness or change its cross-sectional shape.

1.36 Extrusion
Definition
Extrusion is a metal-forming process in which a billet is forced through a die opening to produce a component or section having a desired cross-sectional profile.

1.37 Drawing

Definition
Drawing is a metal-forming process in which a material is pulled through a die to reduce its cross-sectional area or modify its shape.

1.38 Welding

Definition
Welding is a joining process used to produce a permanent joint between materials by applying suitable heat, pressure, or a combination of heat and pressure, with or without filler material depending on the process.

1.39 Brazing

Definition.

Brazing is a joining process in which a filler metal is melted and distributed between closely fitted surfaces by capillary action, while the base metals are not melted.

1.40 Soldering

Definition
Soldering is a joining process in which a relatively low-melting-point filler metal is used to join components without melting the base materials.

1.41 Fitting

Definition
Fitting is a bench-work operation involving the accurate shaping, sizing, finishing and assembly of components using hand tools and related equipment.

CHAPTER 1 — QUICK REVISION

Term Key Meaning

Workshop Place for technical/manufacturing activities

Manufacturing Conversion of raw material into useful products

Process Planned method of producing a desired change

Operation Specific manufacturing activity

Workpiece Material being processed

Raw Material Basic input material

Machine Tool Power-driven manufacturing machine

Cutting Tool Removes material during machining

Jig Holds work and guides tool

Fixture Holds and locates work

Gauge Checks dimensions/limits

Accuracy Closeness to true value

Precision Repeatability

Tolerance Permissible dimensional variation

Allowance Intentional difference between mating dimensions

Machining Removal of unwanted material

Casting Shaping by pouring molten material into mould

Forging Plastic deformation by compressive forces

Rolling Passing metal between rotating rolls

Extrusion Forcing material through a die

Drawing Pulling material through a die

Welding Permanent joining process

Brazing Joining with filler metal without melting base metal

Soldering Low-temperature filler-metal joining

Fitting Accurate bench-work shaping and assembly

Q51. Which of the following best defines a manufacturing process?

A. A method of transporting raw materials
B. A planned sequence of activities used to convert material into a desired product
C. A method of selling products
D. A method of storing finished goods
Answer: B. A planned sequence of activities used to convert material into a desired product
Explanation: A manufacturing process consists of planned activities that transform raw material into a component or finished product having the required shape, dimensions and properties.
Question

Q52. Which of the following is a primary manufacturing process?

A. Casting
B. Inspection
C. Measurement
D. Transportation
Answer: A. Casting
Explanation: Casting is generally considered a primary manufacturing process because a useful shape is produced directly from molten material.
Question

Q53. Which of the following is primarily a material-removal process?
A. Forging
B. Rolling
C. Machining
D. Casting
Answer: C. Machining
Explanation: Machining removes unwanted material from a workpiece to obtain the required dimensions, geometry and surface finish.
Question

Q54. Which manufacturing process changes the shape mainly by plastic deformation?

A. Metal forming
B. Grinding
C. Drilling
D. Turning
Answer: A. Metal forming
Explanation: Forming processes change the geometry of a material through plastic deformation, generally without significant material removal.
Question

Q55. Which of the following is an example of a metal-forming process?
A. Forging
B. Drilling
C. Grinding
D. Boring
Answer: A. Forging
Explanation: Forging changes the shape of metal through plastic deformation caused mainly by compressive forces.
Question

Q56. Which process involves passing a workpiece between rotating rolls?

A. Extrusion
B. Rolling
C. Drawing
D. Forging
Answer: B. Rolling
Explanation: Rolling uses rotating rolls to reduce thickness or alter the cross-sectional profile of the material.
Question

Q57. Which process forces a billet through a die?
A. Drawing
B. Extrusion
C. Rolling
D. Welding
Answer: B. Extrusion
Explanation: In extrusion, compressive force pushes the billet through a die opening to obtain the desired profile.
Question

Q58. Which process pulls material through a die?
A. Extrusion
B. Drawing
C. Forging
D. Casting
Answer: B. Drawing
Explanation: Drawing reduces the cross-sectional area of a material by pulling it through a die.
Question

Q59. Which of the following is a permanent joining process?

A. Welding
B. Turning
C. Milling
D. Grinding
Answer: A. Welding
Explanation: Welding produces a permanent joint between two or more components.
Question

Q60. In which joining process is a filler metal generally used without melting the base metals?

A. Welding
B. Brazing
C. Forging
D. Rolling
Answer: B. Brazing
Explanation: During brazing, the filler metal melts and flows into the joint while the base materials remain below their melting temperatures.
Question

Q61. Which joining process generally uses a lower-temperature filler metal than brazing?

A. Welding
B. Soldering
C. Forging
D. Casting
Answer: B. Soldering
Explanation: Soldering uses a relatively low-melting-point filler metal and normally does not melt the base materials.
Question

Q62. Which of the following is NOT a material-removal process?

A. Turning
B. Milling
C. Forging
D. Drilling
Answer: C. Forging
Explanation: Forging is a metal-forming process. It changes the shape of the workpiece mainly through plastic deformation rather than removing material.
Question

Q63. Which machine tool is mainly used for producing cylindrical surfaces by turning?

A. Lathe
B. Shaper
C. Planer
D. Slotter
Answer: A. Lathe
Explanation: The lathe is primarily used for turning operations in which the workpiece rotates relative to the cutting tool.
Question

Q64. A machine tool used primarily for producing flat surfaces with a reciprocating cutting tool is:

A. Shaper
B. Lathe
C. Milling machine
D. Grinding machine
Answer: A. Shaper
Explanation: A shaper produces surfaces using the reciprocating motion of a single-point cutting tool.
Question

Q65. Which machine uses a rotating multi-point cutting tool?

A. Milling machine
B. Shaper
C. Planer
D. Lathe
Answer: A. Milling machine
Explanation: A milling cutter rotates and has multiple cutting edges.
Question

Q66. Which of the following is primarily an abrasive machining process?
A. Grinding
B. Forging
C. Casting
D. Welding
Answer: A. Grinding
Explanation: Grinding removes material using abrasive grains contained in a grinding wheel or other abrasive tool.
Question

Q67. Which term describes the amount by which a dimension is allowed to vary?
A. Allowance
B. Tolerance
C. Accuracy
D. Precision
Answer: B. Tolerance
Explanation: Tolerance is the permissible variation in a specified dimension.
Question

Q68. For a dimension of 25.00 ± 0.02 mm, the upper limit is:
A. 24.98 mm
B. 25.00 mm
C. 25.02 mm
D. 25.04 mm
Answer: C. 25.02 mm
Explanation:
Upper limit = 25.00 + 0.02
= 25.02 mm
Question

Q69. For a dimension of 25.00 ± 0.02 mm, the lower limit is:
A. 24.96 mm
B. 24.98 mm
C. 25.02 mm
D. 25.04 mm
Answer: B. 24.98 mm
Explanation:
Lower limit = 25.00 − 0.02
= 24.98 mm
Question

Q70. The total tolerance for 25.00 ± 0.02 mm is:
A. 0.01 mm
B. 0.02 mm
C. 0.04 mm
D. 25.02 mm
Answer: C. 0.04 mm
Explanation:
Total tolerance = Upper limit − Lower limit
= 25.02 − 24.98
= 0.04 mm
Question

Q71. Which term indicates closeness of a measured value to the true value?
A. Precision
B. Accuracy
C. Tolerance
D. Allowance
Answer: B. Accuracy
Explanation: Accuracy indicates how close a measurement is to the true or accepted value.
Question

Q72. Repeated measurements that are very close to one another indicate high:
A. Accuracy only
B. Precision
C. Tolerance
D. Allowance
Answer: B. Precision
Explanation: Precision is associated with repeatability or consistency of measurements.
Question

Q73. A set of measurements may be precise but not accurate when:
A. They are close to one another but far from the true value
B. They are all exactly equal to the true value
C. There is no measurement
D. The instrument has no scale
Answer: A. They are close to one another but far from the true value
Explanation: Precision concerns consistency, whereas accuracy concerns closeness to the true value.
Question

Q74. Which instrument is commonly used for accurate measurement of external dimensions?
A. Hammer
B. Micrometer
C. Chisel
D. Hacksaw
Answer: B. Micrometer
Explanation: A micrometer is a precision measuring instrument used for measuring dimensions such as external diameter or thickness within its range.
Question

Q75. Which instrument can commonly measure external dimensions, internal dimensions and depth?
A. Vernier caliper
B. Hammer
C. File
D. Scriber
Answer: A. Vernier caliper
Explanation: A standard Vernier caliper can measure external and internal dimensions and depth.
Question

Q76. Which tool is primarily used for marking lines on a metal workpiece?
A. Scriber
B. Hammer
C. Spanner
D. File
Answer: A. Scriber
Explanation: A scriber is used to mark fine lines on metal surfaces during layout and marking operations.
Question

Q77. Which tool is commonly used to check whether two surfaces are at right angles?
A. Try square
B. Divider
C. Scriber
D. File
Answer: A. Try square
Explanation: A try square is used to check and mark approximately 90° angles.
Question

Q78. Which tool is used to remove small amounts of material by rubbing its abrasive surface against the workpiece?
A. File
B. Hammer
C. Spanner
D. Scriber
Answer: A. File
Explanation: A file is a hand tool having abrasive teeth used mainly for sizing, shaping and finishing.
Question

Q79. Which tool is commonly used to cut metal manually?
A. Hacksaw
B. Try square
C. Divider
D. Micrometer
Answer: A. Hacksaw
Explanation: A hacksaw is a hand-operated cutting tool used for cutting metal and other materials.
Question

Q80. Which of the following is a marking tool?
A. Divider
B. Lathe
C. Grinding wheel
D. Drill press
Answer: A. Divider
Explanation: A divider is commonly used for transferring measurements and marking arcs or circles on a workpiece.
Question

Q81. Which operation involves producing an external cylindrical surface on a lathe?
A. Turning
B. Milling
C. Grinding
D. Broaching
Answer: A. Turning
Explanation: Turning removes material from the external surface of a rotating workpiece using a single-point cutting tool.
Question

Q82. Which lathe operation produces a flat surface at the end of a cylindrical workpiece?
A. Facing
B. Knurling
C. Threading
D. Grooving
Answer: A. Facing
Explanation: Facing produces a flat surface perpendicular to the axis of rotation.
Question

Q83. Which operation is used to produce a helical thread on a workpiece?
A. Thread cutting
B. Facing
C. Filing
D. Grinding only
Answer: A. Thread cutting
Explanation: Thread cutting on a lathe produces helical threads by coordinating spindle rotation with longitudinal tool movement.
Question

Q84. Which operation produces a roughened pattern on a cylindrical surface?
A. Knurling
B. Facing
C. Boring
D. Reaming
Answer: A. Knurling
Explanation: Knurling produces a patterned surface, commonly to improve grip.
Question

Q85. Which operation is used to enlarge an existing hole accurately?
A. Boring
B. Forging
C. Rolling
D. Casting
Answer: A. Boring
Explanation: Boring enlarges and improves an existing hole using a single-point or suitable boring tool.
Question

Q86. Which operation is generally used to improve the dimensional accuracy and finish of an existing hole?
A. Reaming
B. Forging
C. Rolling
D. Welding
Answer: A. Reaming
Explanation: Reaming is a finishing operation used to bring an existing hole closer to the required size and improve its surface finish.
Question

Q87. Which process is used to produce a hole initially in a solid workpiece?
A. Drilling
B. Boring
C. Reaming
D. Honing
Answer: A. Drilling
Explanation: Drilling is normally used to produce a new circular hole in a solid workpiece.
Question

Q88. Which of the following is a surface-finishing process?
A. Grinding
B. Forging
C. Casting
D. Extrusion
Answer: A. Grinding
Explanation: Grinding can produce accurate dimensions and improved surface finish.
Question

Q89. Which process uses a mould cavity?
A. Casting
B. Turning
C. Milling
D. Drilling
Answer: A. Casting
Explanation: Casting uses a mould cavity into which molten material is introduced.
Question

Q90. The cavity in a mould generally represents the:
A. Cutting-tool geometry
B. Desired external shape of the casting
C. Machine-bed shape
D. Measuring-instrument shape
Answer: B. Desired external shape of the casting
Explanation: The mould cavity provides the required geometry into which molten material solidifies.
Question

Q91. Which component of a casting system helps compensate for shrinkage during solidification?
A. Riser
B. Cutting tool
C. Fixture
D. Micrometer
Answer: A. Riser
Explanation: A riser acts as a reservoir of molten metal and helps feed the casting during solidification to compensate for shrinkage.
Question

Q92. A pattern is primarily used in:
A. Casting
B. Turning
C. Grinding
D. Welding
Answer: A. Casting
Explanation: A pattern is used to produce the mould cavity required for casting.
Question

Q93. Which of the following is associated with moulding?
A. Foundry
B. Machine shop only
C. Fitting bench only
D. Metrology laboratory only
Answer: A. Foundry
Explanation: Moulding is a major activity in foundry work, where mould cavities are prepared for casting.
Question

Q94. Which of the following is primarily a joining operation?
A. Welding
B. Turning
C. Drilling
D. Milling
Answer: A. Welding
Explanation: Welding is used to create a permanent joint between components.
Question

Q95. Which process can join metals using a filler metal while keeping the base metals below their melting temperature?
A. Brazing
B. Turning
C. Milling
D. Drilling
Answer: A. Brazing
Explanation: Brazing relies on melting and flowing of the filler metal while the base metals remain solid.
Question

Q96. Which term describes the ability of a material to return to its original shape after removal of load, within its elastic limit?
A. Elasticity
B. Plasticity
C. Brittleness
D. Hardness
Answer: A. Elasticity
Explanation: Elasticity is the property by which a material tends to regain its original shape after the deforming load is removed, provided the elastic limit has not been exceeded.
Question

Q97. A material that fractures with little plastic deformation is described as:
A. Ductile
B. Brittle
C. Malleable
D. Elastic
Answer: B. Brittle
Explanation: Brittle materials generally undergo little plastic deformation before fracture.
Question

Q98. The ability of a material to withstand deformation under load is related to:
A. Strength
B. Colour
C. Density only
D. Thermal conductivity only
Answer: A. Strength
Explanation: Strength is the ability of a material to withstand applied loads without failure.
Question

Q99. Which term represents resistance to deformation under elastic loading?
A. Stiffness
B. Ductility
C. Plasticity
D. Brittleness
Answer: A. Stiffness
Explanation: Stiffness is the resistance offered by a material or component to elastic deformation.
Question

Q100. Which sequence represents a typical basic manufacturing transformation?
A. Finished product → raw material → manufacturing
B. Raw material → manufacturing processes → finished product
C. Product → advertising → raw material
D. Inspection → raw material → transportation
Answer: B. Raw material → manufacturing processes → finished product
Explanation: Manufacturing begins with raw or semi-finished material and applies suitable processes to obtain a product meeting the required specifications.
Question

Important Process Differences

Process Basic Principle

Casting Molten material → mould → solidification

Forging Plastic deformation by compressive force

Rolling Material passes between rotating rolls

Extrusion Material forced through die

Drawing Material pulled through die

Machining Unwanted material removed

Welding Permanent joining

Brazing Filler metal joins parts without melting base metals

Soldering Lower-temperature filler-metal joining

Grinding Abrasive material removal

CHAPTER 2 — ENGINEERING MATERIALS

2.1 Introduction

Engineering materials are the basic materials used for manufacturing machines, tools, structures, components and other engineering products.
A proper understanding of engineering materials is essential in Workshop Technology, because the selection of a material depends on its strength, hardness, toughness, ductility, machinability, corrosion resistance, cost, availability and intended application.
Engineering materials can broadly be classified into:
Metallic materials
Non-metallic materials
Composite materials
Metallic materials are further divided into:
Ferrous materials
Non-ferrous materials

2.2 Engineering Material

Definition
An engineering material is a material having suitable physical, mechanical, chemical or thermal properties that can be used for manufacturing engineering components, machines, tools or structures.
Examples
Steel
Cast iron
Aluminium
Copper
Brass
Bronze
Plastics
Ceramics
Composites
Exam Point
Material selection depends on the required properties and application of the component.

2.3 Metals

Definition
A metal is an element or material generally characterized by good electrical and thermal conductivity, metallic lustre, ductility and malleability.
Common Engineering Metals
Iron
Copper
Aluminium
Zinc
Nickel
Magnesium
Titanium

2.4 Ferrous Materials

Definition
Ferrous materials are materials in which iron is the principal constituent.
Major Examples
Cast iron
Steel
Carbon steel
Alloy steel
Stainless steel
Important Point
The word ferrous is derived from ferrum, the Latin word for iron.

2.5 Non-Ferrous Materials

Definition
Non-ferrous materials are metals and alloys in which iron is not the principal constituent.
Examples
Aluminium
Copper
Zinc
Magnesium
Titanium
Brass
Bronze
Major Characteristics
Many non-ferrous metals offer:
Good corrosion resistance
Low density
Good electrical conductivity
Good thermal conductivity

2.6 Alloy

Definition
An alloy is a metallic material formed by combining two or more elements, at least one of which is generally a metal, to obtain desirable properties.
Examples
Brass = Copper + Zinc
Bronze = Copper + Tin
(as the conventional/basic definition)
Steel = Iron + Carbon, with other elements possibly present.
Why Are Alloys Used?
Alloying can improve:
Strength
Hardness
Wear resistance
Corrosion resistance
Machinability
Heat resistance

2.7 Steel

Definition
Steel is an iron-based alloy containing carbon as an important alloying element, generally with carbon content below that of cast irons and with possible additions of other alloying elements.
Common Types
Plain carbon steel
Low-carbon steel
Medium-carbon steel
High-carbon steel
Alloy steel
Stainless steel

2.8 Carbon Steel

Definition
Carbon steel is steel in which carbon is the principal alloying element and the properties are primarily controlled by carbon content, with other elements present in relatively limited amounts.
Classification
Depending on carbon content, carbon steels are commonly classified as:
Low-carbon steel
Medium-carbon steel
High-carbon steel

2.9 Low-Carbon Steel

Definition
Low-carbon steel is steel containing a relatively low percentage of carbon.
General Characteristics
Good ductility
Good weldability
Good machinability
Relatively low hardness
Relatively low strength compared with higher-carbon steels
Applications

Sheets
Structural components
Automobile components
Nuts and bolts
General fabrication

2.10 Medium-Carbon Steel

Definition
Medium-carbon steel contains more carbon than low-carbon steel and generally provides a balance between strength, hardness and ductility.
Applications
Shafts
Axles
Gears
Machine components

2.11 High-Carbon Steel

Definition
High-carbon steel contains a relatively high percentage of carbon and generally has higher hardness and strength but lower ductility than low-carbon steel.
Applications
Cutting tools
Springs
High-strength wires
Dies
Wear-resistant components

2.12 Cast Iron

Definition
Cast iron is an iron-carbon alloy containing a relatively high carbon content, generally above the carbon content range of steels.
General Characteristics
Good castability
Good compressive strength
Good wear resistance in many grades
Good vibration-damping capacity
Generally brittle compared with steels
Applications
Machine beds
Engine blocks
Pump bodies
Pipes
Housings

2.13 Grey Cast Iron

Definition
Grey cast iron is cast iron in which carbon is present predominantly in the form of graphite flakes, giving the fractured surface a grey appearance.
Characteristics
Good machinability
Good damping capacity
Good castability
Relatively brittle
Applications
Machine beds
Engine blocks
Housings
Bases

2.14 White Cast Iron

Definition
White cast iron is cast iron in which carbon is predominantly present in combined form, mainly as cementite, giving a white appearance on fracture.
Characteristics
High hardness
High wear resistance
Poor machinability
Brittle

2.15 Malleable Cast Iron

Definition
Malleable cast iron is produced by heat treating suitable white cast iron to improve its ductility and toughness.
Applications
Pipe fittings
Brackets
Small machine components

2.16 Ductile Cast Iron

Definition
Ductile cast iron, also called nodular cast iron, is cast iron in which graphite occurs mainly in spheroidal or nodular form.
Characteristics
Better ductility than grey cast iron
Good strength
Good toughness
Good wear resistance
2.17 Alloy Steel
Definition
Alloy steel is steel containing deliberate additions of alloying elements such as chromium, nickel, molybdenum, manganese or vanadium to obtain specific properties.
Applications
Automobile components
Gears
Shafts
Pressure vessels
Aerospace components
Dies and tools

2.18 Stainless Steel

Definition
Stainless steel is a group of alloy steels containing sufficient chromium to provide substantial resistance to corrosion through formation of a protective chromium-rich oxide film.
Applications
Kitchen equipment
Chemical-processing equipment
Medical instruments
Food-processing equipment
Architectural applications
Exam Point
Chromium is the key alloying element associated with stainless-steel corrosion resistance.

2.19 Copper

Definition
Copper is a non-ferrous metal known for its excellent electrical and thermal conductivity, ductility and corrosion resistance.
Applications
Electrical wires
Electrical components
Heat exchangers
Pipes
Conductors

2.20 Aluminium

Definition
Aluminium is a lightweight non-ferrous metal having good corrosion resistance, good thermal and electrical conductivity and good formability.
Applications
Aircraft components
Automobile components
Electrical applications
Window frames
Packaging
Heat exchangers

2.21 Brass

Definition
Brass is a copper-zinc alloy.
Characteristics
Good machinability
Good corrosion resistance
Attractive appearance
Good electrical and thermal conductivity compared with many other engineering materials
Applications
Valves
Fittings
Fasteners
Electrical components
Decorative components
Exam Point
Brass → Copper + Zinc

2.22 Bronze

Definition
Bronze is traditionally a copper-tin alloy, although the term is also used for several copper-based alloys containing other elements.
Applications
Bearings
Bushes
Gears
Marine components
Valves
Exam Point
Traditional bronze → Copper + Tin

2.23 Zinc

Definition
Zinc is a non-ferrous metal commonly used for corrosion protection of steel and in the production of alloys such as brass.
Major Application
Galvanizing uses zinc coating to protect steel or iron from corrosion.
2.24 Magnesium
Definition
Magnesium is a very lightweight structural metal used where low weight is important.
Applications
Aerospace components
Automobile components
Portable equipment
Lightweight structural parts

2.25 Titanium

Definition
Titanium is a strong, relatively lightweight metal with excellent corrosion resistance and a high strength-to-weight ratio.
Applications
Aerospace
Chemical processing
Medical implants
Marine applications

2.26 Mechanical Properties

Definition
Mechanical properties describe how a material behaves when subjected to mechanical forces or loads.
Important mechanical properties include:
Strength
Hardness
Toughness
Ductility
Malleability
Elasticity
Plasticity
Stiffness
Resilience
Fatigue strength
Creep resistance

2.27 Strength

Definition
Strength is the ability of a material to withstand an applied load without failure.
Important types include:
Tensile strength
Compressive strength
Shear strength
Bending strength

2.28 Hardness

Definition
Hardness is the resistance of a material to localized plastic deformation such as indentation, scratching or wear.
Common Hardness Tests
Brinell
Rockwell
Vickers

2.29 Toughness

Definition
Toughness is the ability of a material to absorb energy and undergo deformation before fracture.
Important Point
A tough material can generally withstand impact or sudden loading better than a brittle material.

2.30 Ductility

Definition
Ductility is the ability of a material to undergo significant plastic deformation under tensile loading before fracture.
Example
Copper is generally considered a highly ductile engineering metal.

2.31 Malleability

Definition
Malleability is the ability of a material to undergo plastic deformation under compressive loading and be formed into thin sheets without cracking.
Exam Point
Ductility → tensile deformation
Malleability → compressive deformation

2.32 Brittleness

Definition
Brittleness is the tendency of a material to fracture with little or limited plastic deformation.
Example
Many forms of cast iron are relatively brittle compared with ductile steels.

2.33 Elasticity

Definition
Elasticity is the property by which a material tends to return to its original shape and dimensions after removal of the applied load, provided the elastic limit has not been exceeded.

2.34 Plasticity

Definition
Plasticity is the ability of a material to undergo permanent deformation without fracture.

2.35 Stiffness

Definition
Stiffness is the resistance offered by a material or component to elastic deformation.
Exam Point
A material may have high strength but a component’s deformation under load is also strongly related to its stiffness.

2.36 Resilience
Definition

Resilience is the ability of a material to absorb energy within its elastic limit and release that energy when the load is removed.

2.37 Fatigue

Definition
Fatigue is the progressive failure of a material caused by repeated or fluctuating stresses, often at stress levels below the material’s static strength.
Common Examples
Rotating shafts
Springs
Aircraft components
Connecting rods

2.38 Creep

Definition
Creep is the slow, time-dependent deformation of a material under sustained load, particularly at elevated temperature.
Important Point
Creep is especially important in:
Boilers
Turbines
Engines
High-temperature piping
Power-plant components

2.39 Wear

Definition
Wear is the progressive loss or displacement of material from a surface due to interaction with another surface or environment.
Common Types
Adhesive wear
Abrasive wear
Corrosive wear
Fatigue wear

2.40 Corrosion Resistance

Definition
Corrosion resistance is the ability of a material to resist deterioration caused by chemical or electrochemical interaction with its environment.
Example
Stainless steel generally has much better corrosion resistance than ordinary carbon steel because of its chromium-containing passive surface film.

QUICK REVISION TABLE

Material/Property Key Point

Ferrous material Iron is principal constituent

Non-ferrous material Iron is not principal constituent

Steel Iron-based alloy with carbon as an important constituent

Cast iron High-carbon iron alloy

Brass Copper + Zinc

Bronze Traditionally Copper + Tin

Stainless steel Chromium-containing corrosion-resistant steel

Copper Excellent electrical conductivity

Aluminium Lightweight and corrosion resistant

Strength Resistance to applied load

Hardness Resistance to indentation/wear

Toughness Energy absorption before fracture

Ductility Plastic deformation in tension

Malleability Plastic deformation in compression

Elasticity Recovery after removal of load

Plasticity Permanent deformation

Stiffness Resistance to elastic deformation

Resilience Elastic energy absorption

Fatigue Failure under repeated/fluctuating stress

Creep Time-dependent deformation under sustained load

Wear Progressive material loss

Corrosion resistance Resistance to environmental deterioration

CHAPTER 2 — IMPORTANT EXAM POINTS

Remember These Combinations

Brass → Cu + Zn

Bronze → Cu + Sn

Stainless Steel → Cr is essential for corrosion resistance

Ferrous → Iron-based

Ductility → Tensile deformation

Malleability → Compressive deformation

Hardness → Indentation

Toughness → Energy absorption before fracture

Elasticity → Returns after load removal

Plasticity → Permanent deformation

Fatigue → Repeated/fluctuating load

Creep → Time + sustained load

Q1. Which of the following is a ferrous material?
A. Aluminium
B. Copper
C. Cast iron
D. Brass
Answer: C. Cast iron
Explanation: Ferrous materials are iron-based materials. Cast iron contains iron as its principal constituent.
Question

Q2. Which of the following is a non-ferrous metal?
A. Mild steel
B. Cast iron
C. Aluminium
D. Carbon steel
Answer: C. Aluminium
Explanation: Aluminium is a non-ferrous metal because iron is not its principal constituent.
Question

Q3. Brass is primarily an alloy of:
A. Copper and tin
B. Copper and zinc
C. Iron and carbon
D. Aluminium and copper
Answer: B. Copper and zinc
Explanation: Brass is conventionally defined as a copper-zinc alloy.
Question
Q4. Bronze is tr

aditionally an alloy of:
A. Copper and zinc
B. Copper and tin
C. Iron and carbon
D. Aluminium and magnesium
Answer: B. Copper and tin
Explanation: Traditional bronze is a copper-tin alloy. There are also many other copper-based alloys commercially called bronzes.
Question

Q5. The principal alloying element responsible for the corrosion resistance of stainless steel is:
A. Carbon
B. Chromium
C. Sulphur
D. Silicon
Answer: B. Chromium
Explanation: Chromium promotes formation of a thin, protective passive oxide film that provides stainless steels with their characteristic corrosion resistance.
Question

Q6. Which material is generally known for excellent electrical conductivity?
A. Copper
B. Cast iron
C. High-carbon steel
D. Glass
Answer: A. Copper
Explanation: Copper has very high electrical conductivity and is widely used for electrical conductors and cables.
Question

Q7. Which of the following is a major advantage of aluminium?
A. Very high density
B. Low density
C. Extremely high hardness in pure form
D. Poor corrosion resistance
Answer: B. Low density
Explanation: Aluminium is lightweight and has good corrosion resistance, making it useful in transport and aerospace applications.
Question

Q8. Which material is commonly used for electrical wires?
A. Copper
B. Cast iron
C. Tool steel
D. White cast iron
Answer: A. Copper
Explanation: Copper combines excellent electrical conductivity with good ductility and is therefore widely used for electrical wiring.
Question

Q9. Which of the following is a ferrous alloy?
A. Brass
B. Bronze
C. Steel
D. Aluminium alloy
Answer: C. Steel
Explanation: Steel is an iron-based alloy and is therefore classified as a ferrous material.
Question

Q10. Which of the following is generally considered a lightweight engineering metal?
A. Aluminium
B. Lead
C. Cast iron
D. Steel
Answer: A. Aluminium
Explanation: Aluminium has relatively low density compared with steel and many other structural metals.
Question

Q11. Which property represents resistance to indentation?
A. Ductility
B. Hardness
C. Elasticity
D. Plasticity
Answer: B. Hardness
Explanation: Hardness is commonly evaluated through resistance to indentation, scratching or localized plastic deformation.
Question

Q12. Which property represents the ability to absorb energy before fracture?
A. Toughness
B. Hardness
C. Stiffness
D. Brittleness
Answer: A. Toughness
Explanation: Toughness is the ability to absorb energy and undergo deformation before fracture.
Question

Q13. The ability of a material to undergo plastic deformation in tension before fracture is called:
A. Ductility
B. Malleability
C. Hardness
D. Stiffness
Answer: A. Ductility
Explanation: Ductility is particularly associated with plastic deformation under tensile loading.
Question

Q14. The ability of a material to be formed into thin sheets by compressive deformation is called:
A. Ductility
B. Malleability
C. Toughness
D. Hardness
Answer: B. Malleability
Explanation: Malleability is the ability to undergo plastic deformation under compression without cracking.

Question
Q15. Which property allows a material to regain its original shape after removal of load?
A. Plasticity
B. Elasticity
C. Brittleness
D. Toughness
Answer: B. Elasticity
Explanation: Within its elastic limit, an elastic material returns approximately to its original dimensions after removal of the load.

Question
Q16. Which property represents resistance to elastic deformation?
A. Stiffness
B. Ductility
C. Malleability
D. Plasticity
Answer: A. Stiffness
Explanation: Stiffness indicates resistance to elastic deformation.

Question
Q17. A brittle material generally undergoes:
A. Large plastic deformation before fracture
B. Little plastic deformation before fracture
C. Unlimited elastic deformation
D. No deformation at all
Answer: B. Little plastic deformation before fracture
Explanation: Brittle materials generally fracture with relatively little plastic deformation.

Question
Q18. Which of the following is generally more ductile?
A. Glass
B. Copper
C. White cast iron
D. Ceramics
Answer: B. Copper
Explanation: Copper is a highly ductile metal and can undergo considerable plastic deformation before fracture.

Question
Q19. Which property is particularly important for materials subjected to impact loading?
A. Toughness
B. Density
C. Thermal expansion
D. Electrical resistance
Answer: A. Toughness
Explanation: Toughness is the ability to absorb energy before fracture, making it particularly important under impact or shock loading.

Question
Q20. Fatigue failure is generally associated with:
A. Repeated or fluctuating stresses
B. Constant temperature only
C. Static pressure only
D. Melting
Answer: A. Repeated or fluctuating stresses
Explanation: Fatigue is progressive failure caused by repeated or fluctuating stresses.

Question
Q21. Creep is:
A. Sudden fracture due to impact
B. Time-dependent deformation under sustained load
C. Surface scratching
D. Plastic deformation during forging only
Answer: B. Time-dependent deformation under sustained load
Explanation: Creep is a slow, time-dependent deformation that becomes particularly important at elevated temperatures.

Question
Q22. Creep is particularly important in:
A. High-temperature components
B. Room-temperature wooden furniture only
C. Measuring instruments only
D. Hand tools only
Answer: A. High-temperature components
Explanation: Creep becomes significant in components subjected to sustained stress at elevated temperatures, such as turbine and boiler components.

Question
Q23. Which of the following is a common hardness test?
A. Brinell test
B. Tensile test
C. Compression test
D. Impact-only test
Answer: A. Brinell test
Explanation: Brinell, Rockwell and Vickers are widely used hardness-testing methods.

Question
Q24. Which hardness test commonly uses a diamond pyramid indenter?
A. Vickers
B. Brinell
C. Charpy
D. Izod
Answer: A. Vickers
Explanation: The Vickers hardness test uses a diamond pyramid-shaped indenter.

Question
Q25. The Brinell hardness test commonly uses:
A. A steel or carbide ball indenter
B. A diamond cone only
C. A flat plate only
D. A cutting tool
Answer: A. A steel or carbide ball indenter
Explanation: Brinell testing uses a spherical indenter, traditionally hardened steel and commonly tungsten carbide in modern practice.

Question
Q26. Which of the following is an example of a mechanical property?
A. Hardness
B. Colour
C. Density only
D. Electrical conductivity
Answer: A. Hardness
Explanation: Hardness describes material response to mechanical loading and localized deformation.

Question
Q27. Which of the following is a physical property?
A. Density
B. Toughness
C. Hardness
D. Ductility
Answer: A. Density
Explanation: Density is a physical property, whereas hardness, toughness and ductility are mechanical properties.

Question
Q28. Which material is commonly used for machine beds because of its good vibration-damping capacity?
A. Grey cast iron
B. Aluminium foil
C. Copper wire
D. Glass
Answer: A. Grey cast iron
Explanation: Grey cast iron has good vibration-damping characteristics and is therefore widely used for machine-tool beds and bases.

Question
Q29. The graphite in ordinary grey cast iron is predominantly present as:
A. Spherical particles
B. Flakes
C. Needles only
D. Fibres
Answer: B. Flakes
Explanation: Grey cast iron characteristically contains graphite flakes in its microstructure.

Question
Q30. In ductile cast iron, graphite is predominantly present in:
A. Flake form
B. Nodular/spheroidal form
C. Continuous sheet form
D. Powder form
Answer: B. Nodular/spheroidal form
Explanation: The graphite in ductile or nodular cast iron is mainly spheroidal, improving ductility and toughness compared with grey cast iron.

Question
Q31. Which type of cast iron generally has high hardness and poor machinability?
A. White cast iron
B. Grey cast iron
C. Ductile cast iron
D. Malleable cast iron
Answer: A. White cast iron
Explanation: White cast iron contains carbon predominantly in combined form, especially cementite, making it hard and wear-resistant but difficult to machine.

Question
Q32. Malleable cast iron is produced by heat treatment of:
A. Grey cast iron
B. White cast iron
C. Pure aluminium
D. Brass
Answer: B. White cast iron
Explanation: Suitable white cast iron is heat treated to produce malleable cast iron with improved ductility and toughness.

Question
Q33. Which cast iron generally has the best combination of strength and ductility among common cast irons?
A. Ductile cast iron
B. White cast iron
C. Grey cast iron
D. Chilled cast iron
Answer: A. Ductile cast iron
Explanation: The nodular graphite structure of ductile cast iron gives it substantially better ductility and toughness than grey or white cast iron.

Question
Q34. Which material is commonly used for machine-tool beds?
A. Grey cast iron
B. Pure zinc
C. Brass sheet
D. Lead
Answer: A. Grey cast iron
Explanation: Grey cast iron combines good castability, machinability and vibration damping, making it suitable for machine beds.

Question
Q35. Which of the following is a low-carbon steel application?
A. General fabrication and structural components
B. High-speed cutting tools only
C. Grinding-wheel abrasives
D. Glass manufacturing
Answer: A. General fabrication and structural components
Explanation: Low-carbon steels are ductile, weldable and suitable for many general fabrication and structural applications.
Question

Q36. As carbon content in plain carbon steel generally increases, which property tends to increase?
A. Hardness
B. Ductility
C. Weldability
D. Formability
Answer: A. Hardness
Explanation: Increasing carbon content generally increases hardness and strength after suitable processing, while ductility and weldability tend to decrease.
Question

Q37. Which type of steel generally has the highest carbon content among the following?
A. Low-carbon steel
B. Medium-carbon steel
C. High-carbon steel
D. Mild steel
Answer: C. High-carbon steel
Explanation: High-carbon steel contains more carbon than low- and medium-carbon steels.
Question

Q38. Which material is commonly used for springs because of its ability to withstand elastic deformation?
A. Spring steel
B. Grey cast iron
C. Pure lead
D. Glass
Answer: A. Spring steel
Explanation: Spring steels are designed to provide suitable strength and elastic properties for repeated spring action.
Question

Q39. Which alloying element is strongly associated with improved wear and corrosion resistance in many alloy steels?
A. Chromium
B. Oxygen
C. Hydrogen
D. Sulphur only
Answer: A. Chromium
Explanation: Chromium can improve hardness, wear resistance and corrosion resistance depending on composition and heat treatment.
Question

Q40. Nickel in steel can contribute to:
A. Toughness and corrosion resistance
B. Complete loss of strength
C. Zero ductility in every case
D. Elimination of all heat treatment
Answer: A. Toughness and corrosion resistance
Explanation: Nickel is used in alloy steels to improve properties such as toughness and corrosion resistance.
Question

Q41. Which of the following is a non-ferrous alloy?
A. Brass
B. Carbon steel
C. Cast iron
D. Stainless steel
Answer: A. Brass
Explanation: Brass is a copper-zinc alloy and does not have iron as its principal constituent.
Question

Q42. Which material is commonly used for bearings and bushes?
A. Bronze
B. Glass
C. Pure iron only
D. Concrete
Answer: A. Bronze
Explanation: Several bronze alloys have good wear resistance and suitable friction characteristics and are used for bearings and bushes.
Question

Q43. Which metal is commonly used as a coating for protecting steel against atmospheric corrosion?
A. Zinc
B. Copper
C. Tin only
D. Lead only
Answer: A. Zinc
Explanation: Zinc coating, known as galvanizing, is widely used to protect iron and steel from corrosion.

Question
Q44. Galvanizing generally involves coating steel with:
A. Zinc
B. Copper
C. Aluminium only
D. Carbon
Answer: A. Zinc
Explanation: Galvanizing is the application of a zinc coating to iron or steel for corrosion protection.

Question
Q45. Which metal has a high strength-to-weight ratio and excellent corrosion resistance?
A. Titanium
B. Lead
C. Grey cast iron
D. Pure zinc
Answer: A. Titanium
Explanation: Titanium and its alloys are valued for high specific strength and excellent corrosion resistance.

Question
Q46. Which material is widely used in aerospace applications because of its low density?
A. Aluminium alloys
B. Grey cast iron
C. Lead
D. White cast iron
Answer: A. Aluminium alloys
Explanation: Aluminium alloys provide relatively low density with useful strength and corrosion resistance.

Question
Q47. Which of the following is generally a good conductor of both heat and electricity?
A. Copper
B. Rubber
C. Glass
D. Wood
Answer: A. Copper
Explanation: Copper has excellent electrical and thermal conductivity.

Question
Q48. Which material is generally characterized by good castability and vibration damping?
A. Grey cast iron
B. Pure aluminium
C. Copper
D. Titanium
Answer: A. Grey cast iron
Explanation: Grey cast iron flows well during casting and its graphite structure provides useful vibration damping.

Question
Q49. Which property is most directly associated with resistance to scratching?
A. Hardness
B. Ductility
C. Malleability
D. Plasticity
Answer: A. Hardness
Explanation: Hardness is commonly associated with resistance to scratching, indentation and wear.

Question
Q50. Which property is most important when a material must withstand repeated loading for a long period?
A. Fatigue strength
B. Colour
C. Density alone
D. Melting point alone
Answer: A. Fatigue strength
Explanation: Components subjected to repeated or fluctuating loads require adequate fatigue strength to resist fatigue failure.

Question
Q51. Which of the following is NOT a ferrous material?
A. Steel
B. Cast iron
C. Stainless steel
D. Brass
Answer: D. Brass
Explanation: Brass is a copper-zinc alloy and is classified as a non-ferrous material.

Question
Q52. Which of the following is a copper-based alloy?
A. Brass
B. Mild steel
C. Cast iron
D. Stainless steel
Answer: A. Brass
Explanation: Brass is primarily composed of copper and zinc.

Question
Q53. Which material is particularly suitable for electrical conductors?
A. Copper
B. White cast iron
C. High-carbon steel
D. Grey cast iron
Answer: A. Copper
Explanation: Copper’s high electrical conductivity and ductility make it suitable for electrical conductors.

Question
Q54. Which property is particularly desirable in a material used for a cutting tool?
A. High hardness
B. Very low hardness
C. Very high ductility only
D. Very low wear resistance
Answer: A. High hardness
Explanation: Cutting tools must resist deformation and wear at the cutting edge, so high hardness is essential.

Question
Q55. Which material property is most closely associated with resistance to wear?
A. Hardness
B. Malleability
C. Elasticity
D. Thermal expansion
Answer: A. Hardness
Explanation: Hardness generally contributes significantly to resistance against abrasive and surface wear, although wear behavior depends on several factors.

Q56. Which material is generally easier to plastically deform?
A. Ductile material
B. Brittle material
C. Glass
D. White cast iron
Answer: A. Ductile material
Explanation: Ductile materials can undergo significant plastic deformation before fracture.

Question
Q57. Which property is important for a material used in sheet-metal forming?
A. Malleability
B. Brittleness
C. Extremely low ductility
D. Poor formability
Answer: A. Malleability
Explanation: Malleability enables materials to undergo compressive plastic deformation and be formed into sheets.

Question
Q58. Which of the following materials is generally brittle?
A. Grey cast iron
B. Copper
C. Aluminium
D. Mild steel
Answer: A. Grey cast iron
Explanation: Grey cast iron is relatively brittle because of its flake-graphite structure.

Question
Q59. Which property is associated with resistance to sudden impact?
A. Toughness
B. Density
C. Conductivity
D. Thermal expansion
Answer: A. Toughness
Explanation: Toughness measures a material’s ability to absorb energy before fracture and is important under impact loading.

Question
Q60. Which property is particularly important in a material subjected to high temperature for a long time?
A. Creep resistance
B. Colour
C. Electrical resistance only
D. Surface appearance only
Answer: A. Creep resistance
Explanation: Components under sustained stress at high temperatures can undergo creep, so creep resistance is important.

Question
Q61. Which of the following is a common alloying element in stainless steel?
A. Chromium
B. Sodium
C. Calcium
D. Potassium
Answer: A. Chromium
Explanation: Chromium is essential to the corrosion resistance of stainless steels.

Question
Q62. Which of the following is a lightweight non-ferrous metal?
A. Aluminium
B. Cast iron
C. Steel
D. High-carbon steel
Answer: A. Aluminium
Explanation: Aluminium has relatively low density and is widely used where weight reduction is important.

Question
Q63. Which material is commonly used for engine blocks?
A. Cast iron
B. Glass
C. Copper wire
D. Rubber
Answer: A. Cast iron
Explanation: Cast irons, particularly grey cast iron, have good castability, machinability and vibration-damping characteristics. Aluminium alloys are also widely used for engine blocks.
Question

Q64. Which type of cast iron has graphite in nodular form?
A. Ductile cast iron
B. Grey cast iron
C. White cast iron
D. Chilled cast iron
Answer: A. Ductile cast iron
Explanation: Ductile cast iron is characterized by spheroidal or nodular graphite.

Question
Q65. Which cast iron has graphite predominantly in flake form?
A. Grey cast iron
B. Ductile cast iron
C. Malleable cast iron
D. White cast iron
Answer: A. Grey cast iron
Explanation: Graphite flakes give grey cast iron its characteristic appearance and contribute to good vibration damping.

Question
Q66. Which cast iron contains carbon mainly in combined form?
A. White cast iron
B. Grey cast iron
C. Ductile cast iron
D. Malleable cast iron
Answer: A. White cast iron
Explanation: White cast iron contains carbon primarily as cementite and therefore has high hardness and poor machinability.

Question
Q67. Which material is generally preferred for a component requiring good corrosion resistance and relatively low weight?
A. Aluminium alloy
B. Grey cast iron
C. White cast iron
D. Plain carbon steel without protection
Answer: A. Aluminium alloy
Explanation: Aluminium alloys combine low density with good corrosion resistance.

Question
Q68. Which of the following is an example of an alloy?
A. Brass
B. Pure oxygen
C. Pure nitrogen
D. Distilled water
Answer: A. Brass
Explanation: Brass is an alloy of copper and zinc.
Question

Q69. Why are alloying elements added to metals?
A. To obtain desirable properties
B. Always to reduce strength
C. Always to increase weight
D. Only to change colour
Answer: A. To obtain desirable properties
Explanation: Alloying can be used to modify strength, hardness, corrosion resistance, toughness, machinability and other properties.

Question
Q70. Which of the following is generally associated with increasing carbon content in plain carbon steel?
A. Increased hardness and strength
B. Increased ductility in all cases
C. Improved weldability in all cases
D. Elimination of brittleness
Answer: A. Increased hardness and strength
Explanation: Increasing carbon generally raises hardness and strength, while ductility and weldability tend to decrease.

Question
Q71. Which type of steel is generally used where good weldability is required?
A. Low-carbon steel
B. High-carbon steel
C. Extremely high-carbon steel
D. White cast iron
Answer: A. Low-carbon steel
Explanation: Low-carbon steels generally have good weldability because of their relatively low carbon content.

Question
Q72. Which steel is commonly suitable for gears and shafts where greater strength is required than low-carbon steel?
A. Medium-carbon steel
B. Pure copper
C. Aluminium foil
D. Grey cast iron only
Answer: A. Medium-carbon steel
Explanation: Medium-carbon steels provide a useful balance of strength, hardness and ductility and are commonly used for shafts, gears and axles.

Question
Q73. Which steel is commonly used for high-strength wires and springs?
A. High-carbon steel
B. Low-carbon steel only
C. Pure aluminium
D. Grey cast iron
Answer: A. High-carbon steel
Explanation: High-carbon steels can provide high strength and hardness and are used in springs and high-strength wire applications.

Question
Q74. Which property is especially important for a spring material?
A. Resilience
B. Brittleness
C. Very low elasticity
D. Poor fatigue resistance
Answer: A. Resilience
Explanation: Springs must store and release elastic energy, making resilience an important property.

Question
Q75. Which phenomenon is strongly associated with repeated cyclic loading?
A. Fatigue
B. Creep
C. Casting
D. Galvanizing
Answer: A. Fatigue
Explanation: Fatigue failure develops under repeated or fluctuating stresses.

Question
Q76. Which phenomenon is strongly associated with sustained stress at elevated temperature?
A. Creep
B. Fatigue only
C. Hardening
D. Tempering
Answer: A. Creep
Explanation: Creep is time-dependent deformation under sustained stress and is especially significant at elevated temperatures.

Question
Q77. Which property is associated with the ability to resist permanent deformation?
A. Hardness
B. Colour
C. Thermal conductivity
D. Density
Answer: A. Hardness
Explanation: Hardness is commonly associated with resistance to localized permanent deformation such as indentation.

Question
Q78. Which material is commonly selected for a bearing because of suitable wear and friction characteristics?
A. Bronze
B. Glass
C. Concrete
D. Pure iron only
Answer: A. Bronze
Explanation: Several bronze alloys are used for bearings and bushes because of their wear and friction characteristics.

Question
Q79. Which material is widely used for corrosion-resistant kitchen utensils and equipment?
A. Stainless steel
B. White cast iron
C. Plain carbon steel without coating
D. High-carbon steel only
Answer: A. Stainless steel
Explanation: Stainless steel offers good corrosion resistance and is widely used in food-processing and kitchen applications.
Question

Q80. Which metal is commonly used as the base metal in brass and bronze?
A. Copper
B. Iron
C. Aluminium
D. Titanium
Answer: A. Copper
Explanation: Brass and bronze are both copper-based alloys.

Question
Q81. Which of the following is a major advantage of copper?
A. High electrical conductivity
B. Very low electrical conductivity
C. Extremely high brittleness
D. Poor thermal conductivity
Answer: A. High electrical conductivity
Explanation: Copper is one of the most widely used engineering materials for electrical conductors because of its excellent conductivity.

Question
Q82. Which material is commonly used for lightweight automobile components?
A. Aluminium alloy
B. White cast iron
C. Lead
D. Glass
Answer: A. Aluminium alloy
Explanation: Aluminium alloys provide useful strength at relatively low weight.

Question
Q83. Which material is commonly associated with galvanizing?
A. Zinc
B. Copper
C. Tin
D. Nickel
Answer: A. Zinc
Explanation: Galvanizing protects iron and steel by applying a zinc coating.

Question
Q84. Which property allows a metal to be drawn into wires?
A. Ductility
B. Malleability
C. Brittleness
D. Hardness
Answer: A. Ductility
Explanation: Ductility is the ability of a material to undergo tensile plastic deformation and is important in wire drawing.

Question
Q85. Which property allows a metal to be rolled into thin sheets?
A. Malleability
B. Brittleness
C. Hardness only
D. Fatigue
Answer: A. Malleability
Explanation: Malleability allows a material to undergo compressive plastic deformation, making it suitable for sheet formation.

Question
Q86. Which material property is important for a cutting tool to maintain its cutting edge?
A. Hardness
B. High ductility only
C. Malleability
D. Low wear resistance
Answer: A. Hardness
Explanation: Cutting tools require high hardness and wear resistance to retain their cutting edges during machining.

Question
Q87. Which of the following is a thermal property?
A. Thermal conductivity
B. Hardness
C. Toughness
D. Ductility
Answer: A. Thermal conductivity
Explanation: Thermal conductivity describes a material’s ability to conduct heat.

Question
Q88. Which of the following is an electrical property?
A. Electrical conductivity
B. Toughness
C. Hardness
D. Ductility
Answer: A. Electrical conductivity
Explanation: Electrical conductivity indicates how readily a material conducts electric current.

Question
Q89. Which material is commonly preferred where high corrosion resistance and high specific strength are required?
A. Titanium alloy
B. Grey cast iron
C. Plain carbon steel
D. Lead
Answer: A. Titanium alloy
Explanation: Titanium alloys combine high strength-to-weight ratio with excellent corrosion resistance.

Question
Q90. Which of the following is generally NOT a desired property for a cutting tool?
A. High hardness
B. Good wear resistance
C. High hot hardness where appropriate
D. Very low hardness
Answer: D. Very low hardness
Explanation: A cutting tool must retain adequate hardness and resistance to wear and deformation during cutting.

Question
Q91. Which property is most closely associated with the ability to resist elastic deformation?
A. Stiffness
B. Ductility
C. Malleability
D. Brittleness
Answer: A. Stiffness
Explanation: Stiffness represents resistance to elastic deformation.
Question

Q92. Which property describes the ability of a material to absorb energy elastically?
A. Resilience
B. Brittleness
C. Hardness
D. Creep
Answer: A. Resilience
Explanation: Resilience is the capacity to absorb energy within the elastic range.

Question
Q93. Which material generally has good vibration-damping capacity?
A. Grey cast iron
B. Copper wire
C. Aluminium foil
D. Glass
Answer: A. Grey cast iron
Explanation: Graphite flakes in grey cast iron contribute to good vibration damping.

Question
Q94. Which of the following is a major characteristic of white cast iron?
A. High hardness
B. Excellent ductility
C. Very high machinability
D. High malleability
Answer: A. High hardness
Explanation: White cast iron contains hard carbide phases and is highly wear resistant but brittle and difficult to machine.

Question
Q95. Which cast iron is produced by suitable heat treatment of white cast iron?
A. Malleable cast iron
B. Grey cast iron
C. Ductile cast iron
D. Alloy steel
Answer: A. Malleable cast iron
Explanation: Malleable cast iron is produced through heat treatment of suitable white cast iron.

Question
Q96. Which material is most suitable among the following for a component requiring excellent electrical conductivity?
A. Copper
B. Grey cast iron
C. High-carbon steel
D. White cast iron
Answer: A. Copper
Explanation: Copper has excellent electrical conductivity and is widely used in electrical applications.

Question
Q97. Which of the following is an alloy of iron and carbon?
A. Steel
B. Brass
C. Bronze
D. Pure aluminium
Answer: A. Steel
Explanation: Steel is an iron-based alloy in which carbon is an important constituent.

Question
Q98. Which of the following is generally a desirable property for a material used in a machine component exposed to corrosive surroundings?
A. Corrosion resistance
B. High brittleness
C. Very low strength
D. Very poor surface quality
Answer: A. Corrosion resistance
Explanation: Corrosion-resistant materials maintain their useful properties better in corrosive environments.
Question

Q99. Which statement is correct?
A. Ductility is mainly associated with tensile plastic deformation
B. Malleability is only electrical conductivity
C. Toughness means resistance to corrosion only
D. Hardness means electrical conductivity
Answer: A. Ductility is mainly associated with tensile plastic deformation
Explanation: Ductility describes the capacity for plastic deformation under tensile loading before fracture.

Question
Q100. Which of the following correctly matches the material with its conventional composition?
A. Brass — Copper + Zinc
B. Bronze — Iron + Carbon
C. Steel — Copper + Zinc
D. Cast iron — Copper + Tin
Answer: A. Brass — Copper + Zinc
Explanation: Brass is a copper-zinc alloy. Bronze is traditionally copper-tin, while steel and cast iron are iron-carbon-based materials.
Question

CHAPTER 2 — FINAL REVISION CAPSULE

Most Important Material Combinations

Brass → Copper + Zinc

Traditional Bronze → Copper + Tin

Steel → Iron + Carbon-based alloy

Stainless Steel → Chromium-containing steel

Ferrous → Iron is principal constituent

Non-ferrous → Iron is not principal constituent

Galvanizing → Zinc coating

Grey Cast Iron → Graphite flakes

Ductile Cast Iron → Nodular graphite

White Cast Iron → Carbon mainly in combined form

Most Important Properties

Strength → Resistance to applied load

Hardness → Resistance to indentation/scratching

Toughness → Energy absorption before fracture

Ductility → Tensile plastic deformation

Malleability → Plastic deformation under compression

Elasticity → Recovery after unloading

Plasticity → Permanent deformation

Stiffness → Resistance to elastic deformation

Resilience → Elastic energy absorption

Fatigue → Repeated/fluctuating stresses

Creep → Time-dependent deformation under sustained stress

Wear → Progressive material loss

CHAPTER 3 — MECHANICAL PROPERTIES OF ENGINEERING MATERIALS

3.1 Introduction

Mechanical properties describe how an engineering material behaves when subjected to an external force or load.
For Workshop Technology, understanding these properties is important because the selection of material for a machine component depends heavily on its mechanical behaviour.
For example:
A shaft requires adequate strength and toughness.
A spring requires high resilience and fatigue strength.
A cutting tool requires high hardness and wear resistance.
A wire requires good ductility.
A sheet-metal component requires good malleability and formability.
A machine bed benefits from good stiffness and vibration damping.

3.2 Load

Definition
A load is an external force or system of forces acting on a body.
Common Types of Loading
Tensile load
Compressive load
Shear load
Bending load
Torsional load

3.3 Tensile Load

A tensile load tends to pull a body apart.
Example
A rod being pulled from both ends is subjected to tensile loading.
Effect: Increase in length and reduction in cross-sectional dimensions.

3.4 Compressive Load

A compressive load tends to shorten or compress a body.
Example
A column carrying a vertical load is subjected primarily to compression.
Effect: Reduction in length and possible increase in lateral dimensions.

3.5 Shear Load

A shear load tends to cause one part of a body to slide relative to another part.
Example
A rivet or bolt subjected to transverse loading can experience shear.

3.6 Bending Load

A bending load causes a component to curve or bend.
Examples
Beams
Shafts
Levers
Machine components
A bending load can produce both tensile and compressive stresses in different regions of a component.

3.7 Torsional Load

A torsional load produces twisting about the longitudinal axis of a component.
Examples
Shafts
Drive axles
Transmission components

3.8 Stress

Definition
Stress is the internal resisting force developed per unit area of a material when an external load is applied.
For normal stress:
σ=P/A

Where:
σ= stress
P= applied load
A= cross-sectional area
SI Unit
Pascal (Pa)
In engineering applications, MPa and N/mm² are commonly used.
Important Relation
1″ ” N/mm^2=1″ ” MPa

3.9 Tensile Stress

Tensile stress is produced when a member is subjected to a tensile load.
σ_t=P/A

It tends to elongate the material.

3.10 Compressive Stress

Compressive stress is produced when a member is subjected to compressive loading.
σ_c=P/A

It tends to shorten the member.

3.11 Shear Stress

Shear stress acts tangentially to a surface and tends to cause sliding between adjacent layers.
It is commonly represented by:
τ=P/A

for the simple average shear-stress case.

3.12 Strain

Definition
Strain is the deformation produced per unit original dimension.
For linear tensile strain:
ϵ=ΔL/L

Where:
ΔL= change in length
L= original length
Important Point
Strain has no unit because it is a ratio of two lengths.

3.13 Tensile Strain

Tensile strain is produced when a material is subjected to tensile stress.
ϵ_t=”Increase in length” /”Original length”

3.14 Compressive Strain

Compressive strain is produced when a material is subjected to compressive stress.
ϵ_c=”Decrease in length” /”Original length”

3.15 Hooke’s Law

Definition
Hooke’s Law states that, within the elastic limit, stress is directly proportional to strain.
σ∝ϵ

Therefore:
σ=Eϵ

where Eis Young’s modulus.
Important Condition
Hooke’s law is applicable only within the proportional/elastic range as appropriate to the material and loading condition.

3.16 Young’s Modulus

Young’s modulus is the ratio of normal stress to corresponding normal strain within the linear elastic region.
E=σ/ϵ
SI Unit
Pa or N/m²
In engineering:
GPa is commonly used.
Important Point
A higher Young’s modulus generally indicates a stiffer material in axial loading.

3.17 Modulus of Rigidity

The modulus of rigidity, also called shear modulus, is the ratio of shear stress to shear strain within the elastic range.
G=τ/γ
where:
G= modulus of rigidity
τ= shear stress
γ= shear strain

3.18 Bulk Modulus

The bulk modulus is the ratio of hydrostatic pressure to the corresponding volumetric strain.
K=p/(ΔV/V)

It represents resistance to uniform volumetric deformation.

3.19 Poisson’s Ratio

Definition
Poisson’s ratio is the ratio of lateral strain to longitudinal strain in a material under axial loading, with sign convention depending on the formulation.
In magnitude form:
ν=”lateral strain” /”longitudinal strain”

Because a tensile-loaded specimen generally becomes narrower laterally, the signed lateral strain is opposite in sign to the longitudinal strain.

3.20 Elastic Limit

Definition
The elastic limit is the maximum stress up to which a material can return essentially to its original dimensions after removal of the load.
Beyond this region, permanent deformation may remain.

3.21 Proportional Limit

Definition
The proportional limit is the highest stress up to which stress remains directly proportional to strain.
Difference
Proportional limit: stress-strain relationship remains linear.
Elastic limit: material can still substantially recover its original dimensions after unloading.
The two limits may be very close for many engineering materials, but they are conceptually different.

3.22 Yield Point

Definition
The yield point is the stress region at which significant plastic deformation begins without a corresponding large increase in stress, in materials that exhibit a distinct yield phenomenon.
Some materials do not show a sharply defined yield point; in such cases, an offset yield strength may be specified.

3.23 Yield Strength

Definition
Yield strength is the stress at which a specified amount of permanent/plastic deformation begins to be considered significant.
For many metals without a distinct yield point, a 0.2% proof stress is commonly used.

3.24 Ultimate Tensile Strength

Definition
Ultimate tensile strength (UTS) is the maximum engineering tensile stress reached by a specimen during a tensile test.
UTS=”Maximum load” /”Original cross-sectional area”

3.25 Fracture Stress

Fracture stress is the stress associated with the load at which the specimen finally fractures.
In an engineering stress-strain curve, fracture may occur after the ultimate tensile strength has been reached because of necking.

3.26 Plastic Deformation

Definition
Plastic deformation is permanent deformation that remains after the external load is removed.
It occurs when the material is loaded beyond its elastic range.

3.27 Elastic Deformation

Definition
Elastic deformation is recoverable deformation that disappears when the load is removed, provided the material remains within its elastic range.

3.28 Ductility

Ductility is the ability of a material to undergo substantial plastic deformation in tension before fracture.
Common Measures
Percentage elongation
Percentage reduction in area
A higher percentage elongation generally indicates greater ductility.

3.29 Percentage Elongation

Percentage elongation is given by:
%” ” Elongation=(L_f-L_0)/L_0 ×100

Where:
L_0= original gauge length
L_f= final gauge length
3.30 Percentage Reduction in Area
%” ” Reduction” ” in” ” Area=(A_0-A_f)/A_0 ×100

Where:
A_0= original cross-sectional area
A_f= final cross-sectional area
It is also commonly used as an indicator of ductility.

3.31 Toughness

Definition
Toughness is the ability of a material to absorb energy and undergo plastic deformation before fracture.
Important Point
Toughness combines aspects of strength and ductility.
3.32 Resilience

Definition
Resilience is the ability of a material to absorb and store energy elastically.
Modulus of Resilience
The modulus of resilience represents the elastic strain energy absorbed per unit volume up to the elastic limit or relevant yield point.

3.33 Stiffness

Definition
Stiffness is the resistance offered by a body or material to deformation under load.
For axial loading, Young’s modulus is an important material parameter related to stiffness.

3.34 Hardness

Hardness is resistance to localized permanent deformation, commonly measured through indentation tests.
Common Tests
Brinell
Rockwell
Vickers

3.35 Rockwell Hardness Test

The Rockwell test determines hardness based on the depth of indentation produced under specified loading conditions.
Important Point
Rockwell testing is widely used because it is relatively rapid and does not require measuring the indentation diameter optically.

3.36 Brinell Hardness Test

The Brinell test uses a spherical indenter and determines hardness from the size of the indentation produced under a specified load.
Suitable For
It is often useful for relatively large or coarse-grained metallic specimens.

3.37 Vickers Hardness Test

The Vickers test uses a diamond pyramid indenter.
It is suitable for a wide range of materials and can be used for relatively small or thin specimens when appropriate testing conditions are selected.

3.38 Impact Strength

Definition
Impact strength represents the ability of a material to absorb energy under sudden or impact loading.
Common Tests
Charpy impact test
Izod impact test

3.39 Fatigue Strength

Definition
Fatigue strength is the ability of a material to withstand repeated or fluctuating stresses without failure for a specified number of cycles or under specified fatigue conditions.

3.40 Endurance Limit

For some materials, particularly certain steels, an endurance limit is the stress level below which the material can withstand a very large or effectively indefinite number of cycles under specified conditions.
Not all materials exhibit a true endurance limit.

3.41 Creep

Creep is the progressive, time-dependent deformation of a material under sustained stress.
It becomes especially important at elevated temperatures.

3.42 Wear

Wear is the progressive removal, displacement or degradation of material from a surface due to interaction with another surface or environment.
Major Types
Adhesive wear
Abrasive wear
Fatigue wear
Corrosive wear

3.43 Adhesive Wear

Adhesive wear occurs when material is transferred between contacting surfaces due to localized adhesion and subsequent shearing.

3.44 Abrasive Wear

Abrasive wear occurs when a hard surface or hard particles remove material from a softer surface.

3.45 Fatigue Wear

Fatigue wear occurs due to repeated loading and unloading of contacting surfaces, eventually causing surface damage and material removal.

3.46 Corrosive Wear

Corrosive wear occurs when chemical or electrochemical reactions contribute to material removal from a surface.
3.47 Factor of Safety

Definition
The factor of safety (FOS) provides a margin between the strength of a component/material and the allowable working condition.
A simplified form is:
FOS=”Failure strength” /”Allowable working stress”

The precise definition depends on the design criterion and material behavior.
Purpose
It accounts for uncertainties such as:
Variations in material properties
Manufacturing defects
Uncertainty in loading
Service conditions
Design assumptions

3.48 Working Stress

Definition
Working stress, or allowable stress, is the stress level permitted in a component during normal operation according to the applicable design standard and safety considerations.

3.49 Stress Concentration

Definition
Stress concentration is the localized increase in stress around discontinuities such as:
Holes
Notches
Sharp corners
Keyways
Grooves
Important Point
Sharp corners generally produce greater stress concentration than smoothly rounded transitions.

3.50 Engineering Stress vs True Stress

Engineering Stress
σ_e=P/A_0

where A_0is the original cross-sectional area.
True Stress
σ_t=P/A_i

where A_iis the instantaneous cross-sectional area.
Exam Point
Engineering stress uses the original area, while true stress uses the instantaneous area.

QUICK REVISION TABLE

Property/Term Meaning

Load External force/system of forces

Stress Internal force per unit area

Strain Deformation per unit original dimension

Tensile stress Stress due to pulling

Compressive stress Stress due to pushing

Shear stress Stress causing sliding

Young’s modulus Normal stress / normal strain

Shear modulus Shear stress / shear strain

Bulk modulus Hydrostatic stress / volumetric strain

Poisson’s ratio Lateral strain / longitudinal strain

Elasticity Recovery after unloading

Plasticity Permanent deformation

Yield strength Stress associated with specified plastic deformation

UTS Maximum engineering tensile stress

Ductility Plastic deformation in tension

Malleability Plastic deformation under compression

Toughness Energy absorption before fracture

Resilience Elastic energy absorption

Stiffness Resistance to deformation

Hardness Resistance to localized deformation

Fatigue Failure under repeated/fluctuating loading

Creep Time-dependent deformation

Wear Progressive surface/material loss

FOS Margin between failure and allowable condition

Stress concentration Localized increase in stress

IMPORTANT FORMULAS

Normal Stress
σ=P/A

Strain
ϵ=ΔL/L

Young’s Modulus
E=σ/ϵ

Shear Modulus
G=τ/γ

Percentage Elongation
%EL=(L_f-L_0)/L_0 ×100

Percentage Reduction in Area
%RA=(A_0-A_f)/A_0 ×100

Factor of Safety
FOS=”Failure strength” /”Allowable working stress”

Q1. The internal resisting force developed per unit area of a material subjected to an external load is called:
A. Strain
B. Stress
C. Deformation
D. Toughness
Answer: B. Stress
Explanation: Stress represents the internal resistance developed in a material against an applied load. For direct normal loading:
σ=P/A

Q2. The SI unit of stress is:
A. Newton
B. Joule
C. Pascal
D. Watt
Answer: C. Pascal
Explanation: Stress is force per unit area, so its SI unit is N/m², which is called the Pascal (Pa).

Q3. Which of the following is equivalent to 1 MPa?
A. 1 N/m²
B. 1 N/mm²
C. 1000 N/mm²
D. 1 kN/mm²
Answer: B. 1 N/mm²
Explanation:
1″ ” MPa=10^6 “ ” N/m^2=1″ ” N/mm^2

Q4. Strain is defined as:
A. Force per unit area
B. Deformation per unit original dimension
C. Force × distance
D. Energy per unit volume
Answer: B. Deformation per unit original dimension
Explanation: For linear deformation:
ϵ=ΔL/L

Therefore, strain is dimensionless.

Q5. The unit of strain is:
A. N
B. Pa
C. mm
D. No unit
Answer: D. No unit
Explanation: Strain is a ratio of two lengths and therefore has no physical unit.

Q6. A tensile load tends to:
A. Shorten a component
B. Twist a component only
C. Elongate a component
D. Produce no deformation
Answer: C. Elongate a component
Explanation: Tensile loading pulls a component apart and generally increases its length.

Q7. A compressive load tends to:
A. Increase length
B. Decrease length
C. Produce only twisting
D. Produce no stress
Answer: B. Decrease length
Explanation: Compressive loading tends to shorten a component.

Q8. A load acting tangentially to a surface primarily produces:
A. Tensile stress
B. Compressive stress
C. Shear stress
D. Hydrostatic stress
Answer: C. Shear stress
Explanation: Shear stress acts tangentially to the surface and tends to cause relative sliding between adjacent layers.

Q9. The ratio of normal stress to normal strain within the elastic range is:
A. Bulk modulus
B. Young’s modulus
C. Modulus of rigidity
D. Poisson’s ratio
Answer: B. Young’s modulus
Explanation:
E=σ/ϵ

Young’s modulus is an important measure of stiffness in axial loading.

Q10. The SI unit of Young’s modulus is:
A. N
B. N/m²
C. m/N
D. N·m
Answer: B. N/m²
Explanation: Since Young’s modulus is stress divided by dimensionless strain, its unit is the same as stress: Pa or N/m².

Q11. Hooke’s law states that, within the proportional limit:
A. Stress is inversely proportional to strain
B. Stress is directly proportional to strain
C. Stress is independent of strain
D. Strain is always zero
Answer: B. Stress is directly proportional to strain
Explanation:
σ∝ϵ

or
σ=Eϵ

within the applicable linear elastic range.
Q12. Which property indicates resistance to elastic deformation?
A. Stiffness
B. Ductility
C. Plasticity
D. Malleability
Answer: A. Stiffness
Explanation: Stiffness is the resistance offered by a material or component to elastic deformation.

Q13. A material that returns to its original shape after removal of load, within its elastic range, possesses:
A. Plasticity
B. Elasticity
C. Brittleness
D. Creep
Answer: B. Elasticity
Explanation: Elasticity is the ability of a material to recover its original shape and dimensions after the load is removed, provided the elastic range is not exceeded.

Q14. Permanent deformation remaining after removal of load is called:
A. Elastic deformation
B. Plastic deformation
C. Thermal deformation
D. Volumetric deformation only
Answer: B. Plastic deformation
Explanation: Plastic deformation is permanent deformation and does not disappear completely after unloading.

Q15. The maximum stress up to which a material substantially returns to its original dimensions after unloading is called:
A. Ultimate stress
B. Elastic limit
C. Breaking stress
D. Working stress
Answer: B. Elastic limit
Explanation: Beyond the elastic limit, permanent deformation can remain after the load is removed.

Q16. The maximum stress up to which stress is directly proportional to strain is called:

A. Proportional limit
B. Ultimate stress
C. Fracture stress
D. Breaking stress
Answer: A. Proportional limit
Explanation: Up to the proportional limit, stress and strain have a linear relationship.

Q17. The beginning of significant permanent deformation in a ductile material is associated with:
A. Yielding
B. Elastic recovery
C. Hardening only
D. Creep only
Answer: A. Yielding
Explanation: Yielding marks the transition from predominantly elastic behavior to significant plastic deformation.
Q18. Yield strength represents:

A. Stress at which specified plastic deformation occurs
B. Density of the material
C. Melting temperature
D. Thermal conductivity
Answer: A. Stress at which specified plastic deformation occurs
Explanation: For materials without a distinct yield point, a proof or offset yield strength, commonly 0.2%, may be specified.

Q19. The maximum engineering stress reached during a tensile test is called:
A. Yield stress
B. Ultimate tensile strength
C. Working stress
D. Shear stress
Answer: B. Ultimate tensile strength
Explanation: UTS is calculated using the maximum load divided by the original cross-sectional area.
UTS=P_max/A_0

Q20. Which property represents the ability of a material to undergo plastic deformation in tension before fracture?
A. Ductility
B. Hardness
C. Stiffness
D. Brittleness
Answer: A. Ductility
Explanation: Ductility indicates the capacity for plastic deformation under tensile loading.
Q21. Percentage elongation is commonly used as a measure of:

A. Hardness
B. Ductility
C. Stiffness
D. Thermal conductivity
Answer: B. Ductility
Explanation: A greater percentage elongation generally indicates greater ductility.
%EL=(L_f-L_0)/L_0 ×100

Q22. A material capable of being drawn into wires is generally:
A. Ductile
B. Brittle
C. Extremely hard and brittle
D. Non-metallic only
Answer: A. Ductile
Explanation: Wire drawing requires substantial tensile plastic deformation, which is characteristic of ductile materials.

Q23. The ability of a material to be formed into thin sheets by compressive deformation is:

A. Ductility
B. Malleability
C. Toughness
D. Resilience
Answer: B. Malleability
Explanation: Malleability refers particularly to plastic deformation under compressive loading.

Q24. Which property is most closely associated with resistance to indentation?
A. Hardness
B. Ductility
C. Resilience
D. Plasticity
Answer: A. Hardness
Explanation: Hardness is commonly evaluated through resistance to indentation.

Q25. Which of the following is a hardness test?
A. Brinell
B. Charpy
C. Izod
D. Tensile test
Answer: A. Brinell
Explanation: Brinell is a standard indentation hardness test.

Q26. The Rockwell hardness test primarily measures:
A. Indentation depth
B. Tensile elongation
C. Impact energy
D. Percentage reduction in area
Answer: A. Indentation depth
Explanation: Rockwell hardness is determined from the depth of indentation produced under specified loads.

Q27. The Vickers hardness test uses a:
A. Steel ball only
B. Diamond pyramid indenter
C. Cutting tool
D. Flat punch only
Answer: B. Diamond pyramid indenter
Explanation: The Vickers test uses a diamond pyramid, traditionally with a square base.

Q28. The Brinell hardness test commonly uses:
A. A spherical indenter
B. A diamond pyramid only
C. A sharp cutting tool
D. A cylindrical punch only
Answer: A. A spherical indenter
Explanation: Brinell hardness is determined from the indentation made by a spherical indenter.

Q29. Toughness is the ability of a material to:
A. Resist only indentation
B. Absorb energy before fracture
C. Conduct electricity
D. Conduct heat
Answer: B. Absorb energy before fracture
Explanation: Toughness represents the capacity to absorb mechanical energy before fracture.

Q30. Which property is particularly important for a component subjected to shock loading?
A. Toughness
B. Colour
C. Density only
D. Thermal expansion only
Answer: A. Toughness
Explanation: Tough materials can absorb significant energy before fracture and are therefore valuable under impact or shock loading.

Q31. Resilience refers to the ability of a material to:
A. Absorb energy elastically
B. Resist corrosion only
C. Resist melting
D. Undergo permanent deformation only
Answer: A. Absorb energy elastically
Explanation: Resilience is associated with elastic strain-energy storage.

Q32. A spring material should have high:
A. Resilience
B. Brittleness
C. Creep only
D. Thermal expansion
Answer: A. Resilience
Explanation: Springs store and release elastic energy, so high resilience is desirable.

Q33. Fatigue failure occurs mainly due to:
A. Repeated or fluctuating stresses
B. A single static load only
C. Melting
D. Corrosion only
Answer: A. Repeated or fluctuating stresses
Explanation: Fatigue is progressive damage caused by cyclic stress variations.

Q34. Which component is particularly susceptible to fatigue failure?
A. Rotating shaft
B. Stationary brick wall
C. Glass window with no loading
D. Wooden table under no load
Answer: A. Rotating shaft
Explanation: Rotating shafts can experience fluctuating bending and torsional stresses, making fatigue an important design consideration.

Q35. Creep is most significant when a component is subjected to:
A. Sustained load, particularly at elevated temperature
B. No load
C. Only one impact
D. Zero temperature
Answer: A. Sustained load, particularly at elevated temperature
Explanation: Creep is time-dependent deformation under sustained stress and becomes particularly important at elevated temperatures.

Q36. Which of the following is a typical creep-related application?
A. Steam turbine component
B. Hand file at room temperature only
C. Measuring scale
D. Wooden ruler
Answer: A. Steam turbine component
Explanation: Turbine components operate under sustained stress and elevated temperatures, making creep resistance important.

Q37. Wear is best described as:
A. Progressive material loss or surface degradation
B. Elastic recovery
C. Plastic elongation only
D. Increase in mass due to loading
Answer: A. Progressive material loss or surface degradation
Explanation: Wear occurs due to interaction between surfaces or with the environment and may involve material removal or displacement.

Q38. Abrasive wear occurs when:
A. Hard particles or surfaces remove material from a softer surface
B. A material melts completely
C. A component returns to its original shape
D. A material undergoes only elastic deformation
Answer: A. Hard particles or surfaces remove material from a softer surface
Explanation: Abrasive wear results from cutting, ploughing or scratching by harder asperities or particles.
Q39. Adhesive wear is associated with:

A. Material transfer between contacting surfaces
B. Only thermal expansion
C. Only elastic deformation
D. Absence of contact
Answer: A. Material transfer between contacting surfaces
Explanation: Localized adhesion between contacting surfaces can lead to material transfer and subsequent removal.

Q40. Which property is generally important for a cutting tool?
A. High hardness
B. Very low hardness
C. Very high malleability
D. Very low wear resistance
Answer: A. High hardness
Explanation: Cutting tools need adequate hardness and wear resistance to maintain their cutting edge.

Q41. A component has a load of 20,000 N and a cross-sectional area of 1,000 mm². The normal stress is:
A. 2 N/mm²
B. 20 N/mm²
C. 200 N/mm²
D. 20,000 N/mm²
Answer: B. 20 N/mm²
Explanation:
σ=P/A
=20,000/1,000=20″ ” N/mm^2

Therefore, stress = 20 MPa.
Numerical
Q42. A steel rod of original length 500 mm elongates by 1 mm. Its strain is:
A. 0.002
B. 0.02
C. 2
D. 500
Answer: A. 0.002
Explanation:
ϵ=ΔL/L
=1/500=0.002

Numerical
Q43. If the strain in a specimen is 0.005, the percentage strain is:
A. 0.05%
B. 0.5%
C. 5%
D. 50%
Answer: C. 0.5%
Explanation:
0.005×100=0.5%

Therefore, the correct answer is B. 0.5%.
Correction: The options contain the correct answer as B, not C.
Final Answer: B. 0.5%
Numerical
Q44. If stress is 200 MPa and strain is 0.001, Young’s modulus is:
A. 20 MPa
B. 200 MPa
C. 200 GPa
D. 2 GPa
Answer: C. 200 GPa
Explanation:
E=σ/ϵ
E=200/0.001=200,000″ ” MPa

Since:
1000″ ” MPa=1″ ” GPa
E=200″ ” GPa

Numerical
Q45. A rod has an original gauge length of 100 mm and final gauge length of 110 mm. Percentage elongation is:
A. 1%
B. 5%
C. 10%
D. 20%
Answer: C. 10%
Explanation:
%EL=(110-100)/100×100
=10%

Numerical
Q46. A specimen has an original cross-sectional area of 200 mm² and a final area of 150 mm². Percentage reduction in area is:
A. 10%
B. 20%
C. 25%
D. 50%
Answer: C. 25%
Explanation:
%RA=(200-150)/200×100
=50/200×100=25%

Numerical
Q47. If a material has a Young’s modulus of 200 GPa and is subjected to a stress of 100 MPa, its elastic strain is:
A. 0.0005
B. 0.005
C. 0.05
D. 0.5
Answer: A. 0.0005
Explanation:
ϵ=σ/E

Convert:
200″ ” GPa=200,000″ ” MPa

Therefore:
ϵ=100/200000=0.0005

Numerical
Q48. If the failure strength of a component is 600 MPa and its allowable stress is 150 MPa, the factor of safety is:
A. 2
B. 3
C. 4
D. 6
Answer: C. 4
Explanation:
FOS=600/150=4

Numerical
Q49. Which stress-strain region is associated with recoverable deformation?
A. Elastic region
B. Plastic region only
C. Fracture region
D. Necking region only
Answer: A. Elastic region
Explanation: Deformation within the elastic range is substantially recoverable after unloading.
Q50. In an engineering stress-strain curve for a ductile metal, necking generally begins after:
A. The proportional limit
B. The ultimate tensile strength
C. Zero stress
D. The origin
Answer: B. The ultimate tensile strength
Explanation: In a conventional tensile test of a ductile metal, localized necking generally begins after the maximum engineering stress, i.e., the UTS, has been reached.

Q51. Which modulus represents the ratio of shear stress to shear strain?
A. Young’s modulus
B. Bulk modulus
C. Modulus of rigidity
D. Resilience modulus
Answer: C. Modulus of rigidity
Explanation:
G=τ/γ

It is also called the shear modulus.

Q52. Which modulus represents resistance to uniform volumetric deformation?
A. Young’s modulus
B. Bulk modulus
C. Shear modulus
D. Section modulus
Answer: B. Bulk modulus
Explanation: Bulk modulus relates hydrostatic pressure to volumetric strain.

Q53. Poisson’s ratio relates:
A. Longitudinal stress and lateral stress
B. Lateral strain and longitudinal strain
C. Shear stress and normal stress
D. Load and area
Answer: B. Lateral strain and longitudinal strain
Explanation: Poisson’s ratio describes the lateral contraction/expansion associated with longitudinal deformation.
Q54. Which of the following is dimensionless?
A. Young’s modulus
B. Stress
C. Strain
D. Load
Answer: C. Strain
Explanation: Strain is a ratio of two dimensions of the same type and therefore has no unit.

Q55. The stress corresponding to the maximum engineering load in a tensile test is:
A. Yield stress
B. Ultimate tensile stress
C. Proof stress
D. Working stress
Answer: B. Ultimate tensile stress
Explanation: UTS is based on the maximum load divided by the original cross-sectional area.

Q56. Which property is generally associated with a brittle material?
A. Large plastic deformation before fracture
B. Little plastic deformation before fracture
C. Very high ductility
D. Very high malleability
Answer: B. Little plastic deformation before fracture
Explanation: Brittle materials generally fracture with little plastic deformation.

Q57. Which material property is desirable in a shaft subjected to shock loading?
A. Toughness
B. Brittleness
C. Low strength
D. Low fatigue resistance
Answer: A. Toughness
Explanation: Toughness allows a component to absorb significant energy before fracture.

Q58. Which property is especially important for a shaft under repeated rotational loading?
A. Fatigue strength
B. Colour
C. Density only
D. Melting point only
Answer: A. Fatigue strength
Explanation: Rotating shafts can experience cyclic stresses and therefore require adequate fatigue strength.

Q59. Which type of stress is mainly associated with a component subjected to twisting?
A. Tensile stress
B. Compressive stress
C. Shear stress
D. Hydrostatic stress
Answer: C. Shear stress
Explanation: Torsion primarily produces shear stresses in a shaft.

Q60. Which type of loading causes twisting of a shaft?
A. Tensile loading
B. Torsional loading
C. Compressive loading
D. Uniform pressure only
Answer: B. Torsional loading
Explanation: Torsional loading produces a twisting moment about the longitudinal axis.

Q61. Which type of load is primarily responsible for bending a beam?
A. Bending load
B. Torsional load only
C. Pure thermal load
D. Electrical load
Answer: A. Bending load
Explanation: Bending loading causes curvature of the beam and produces tensile and compressive stresses across its section.

Q62. A sharp corner in a machine component can cause:
A. Stress concentration
B. Zero stress
C. Zero deformation
D. Elimination of fatigue
Answer: A. Stress concentration
Explanation: Geometric discontinuities such as sharp corners, holes and keyways can cause localized increases in stress.

Q63. Which feature generally reduces stress concentration compared with a sharp corner?
A. Fillet radius
B. Sharp notch
C. Sudden section change
D. Crack
Answer: A. Fillet radius
Explanation: A smooth fillet reduces the severity of abrupt geometric changes and can lower stress concentration.

Q64. Engineering stress is calculated using:
A. Instantaneous area
B. Original cross-sectional area
C. Final area only
D. Surface area
Answer: B. Original cross-sectional area
Explanation:
σ_e=P/A_0

Engineering stress uses the original cross-sectional area.
Q65. True stress is calculated using:
A. Original area only
B. Instantaneous cross-sectional area
C. Gauge length only
D. Volume only
Answer: B. Instantaneous cross-sectional area
Explanation:
σ_t=P/A_i

where A_iis the instantaneous cross-sectional area.
Q66. A material with high Young’s modulus is generally:
A. More resistant to elastic deformation
B. More ductile in every case
C. More brittle in every case
D. Less stiff
Answer: A. More resistant to elastic deformation
Explanation: Higher Young’s modulus means greater stiffness for a given axial loading condition.

Q67. Young’s modulus primarily indicates:
A. Elastic stiffness
B. Corrosion resistance
C. Electrical conductivity
D. Melting point
Answer: A. Elastic stiffness
Explanation: Young’s modulus is a measure of resistance to elastic deformation in tension or compression.

Q68. Which of the following is NOT a mechanical property?
A. Toughness
B. Hardness
C. Ductility
D. Thermal conductivity
Answer: D. Thermal conductivity
Explanation: Thermal conductivity is a thermal property, while toughness, hardness and ductility are mechanical properties.

Q69. Which of the following is a mechanical property?
A. Ductility
B. Electrical conductivity
C. Thermal expansion
D. Density
Answer: A. Ductility
Explanation: Ductility describes mechanical behavior under loading.

Q70. Which test is commonly used to determine impact toughness?
A. Charpy test
B. Brinell test
C. Rockwell test
D. Vickers test
Answer: A. Charpy test
Explanation: Charpy and Izod are standard impact tests used to evaluate energy absorption under sudden loading.

Q71. The Izod test is used primarily to determine:
A. Impact toughness
B. Hardness
C. Young’s modulus
D. Thermal conductivity
Answer: A. Impact toughness
Explanation: Izod is an impact test in which a notched specimen is struck by a pendulum.

Q72. Which property is generally associated with the area under the complete engineering stress-strain curve up to fracture?
A. Toughness
B. Stiffness only
C. Hardness
D. Resilience only
Answer: A. Toughness
Explanation: The area under the complete stress-strain curve up to fracture represents the energy absorbed per unit volume, associated with toughness.

Q73. The area under the elastic portion of the stress-strain curve represents:
A. Modulus of resilience
B. Ultimate strength
C. Hardness
D. Fatigue strength
Answer: A. Modulus of resilience
Explanation: The elastic area represents elastic strain energy per unit volume.

Q74. Which property is particularly important for a material used in a forming operation?
A. Ductility/formability
B. Brittleness
C. Extremely low plasticity
D. Very low elongation
Answer: A. Ductility/formability
Explanation: Forming operations require sufficient plastic deformation without cracking.

Q75. Which material behavior is associated with permanent shape change?
A. Plasticity
B. Elasticity
C. Resilience
D. Stiffness
Answer: A. Plasticity
Explanation: Plasticity allows permanent deformation without immediate fracture.

Q76. Which property is important in a material used for a punch or die?
A. Hardness and wear resistance
B. Very low hardness
C. Very high malleability only
D. Low strength
Answer: A. Hardness and wear resistance
Explanation: Punches and dies are subjected to contact stresses and wear and therefore require suitable hardness and wear resistance.

Q77. Which of the following can cause premature fatigue failure?
A. Stress concentration
B. Smooth fillet
C. Proper surface finish
D. Correct material selection
Answer: A. Stress concentration
Explanation: Stress concentrations can significantly increase local cyclic stresses and promote fatigue crack initiation.

Q78. Which surface condition generally improves fatigue performance compared with a severely rough surface?
A. Smooth surface
B. Deep scratches
C. Sharp notches
D. Cracks
Answer: A. Smooth surface
Explanation: Surface defects and scratches can act as stress raisers and fatigue-crack initiation sites.

Q79. Which factor is important in creep?
A. Time
B. Time-independent load only
C. Colour
D. Electrical resistance only
Answer: A. Time
Explanation: Creep is fundamentally a time-dependent deformation process.

Q80. Which factor is especially important in high-temperature creep?

A. Temperature
B. Colour
C. Surface polish only
D. Electrical conductivity only
Answer: A. Temperature
Explanation: Creep rates generally increase strongly with temperature for many engineering materials.

Q81. A tensile specimen has an original length of 200 mm and elongates to 204 mm. Its percentage elongation is:
A. 1%
B. 2%
C. 4%
D. 20%
Answer: B. 2%
Explanation:
%EL=(204-200)/200×100
=2%

Numerical
Q82. A component carries 50 kN load over an area of 500 mm². Its average stress is:
A. 10 N/mm²
B. 50 N/mm²
C. 100 N/mm²
D. 500 N/mm²
Answer: C. 100 N/mm²
Explanation:
σ=50,000/500=100″ ” N/mm^2

Therefore, stress = 100 MPa.
Numerical
Q83. A rod of 2 m length elongates by 2 mm. The strain is:
A. 0.001
B. 0.01
C. 0.1
D. 1
Answer: A. 0.001
Explanation:
Convert 2 m to 2000 mm.
ϵ=2/2000=0.001

Numerical
Q84. If Young’s modulus is 210 GPa and the strain is 0.001, the stress is:
A. 21 MPa
B. 210 MPa
C. 2.1 MPa
D. 2100 MPa
Answer: B. 210 MPa
Explanation:
σ=Eϵ
=210×0.001=0.210″ ” GPa
=210″ ” MPa

Numerical
Q85. A material has a failure strength of 800 MPa and a factor of safety of 4. Its allowable stress is:
A. 100 MPa
B. 200 MPa
C. 400 MPa
D. 3200 MPa
Answer: B. 200 MPa
Explanation:
FOS=(Failure” ” strength)/(Allowable” ” stress)

Therefore:
Allowable” ” stress=800/4=200″ ” MPa

Numerical
Q86. A specimen has an original area of 400 mm² and final area of 300 mm². The percentage reduction in area is:
A. 10%
B. 20%
C. 25%
D. 40%
Answer: C. 25%
Explanation:
%RA=(400-300)/400×100
=25%

Numerical
Q87. If the original length of a specimen is 250 mm and the final length is 275 mm, percentage elongation is:
A. 5%
B. 10%
C. 15%
D. 25%
Answer: B. 10%
Explanation:
%EL=(275-250)/250×100=10%

Numerical
Q88. A stress of 150 MPa produces a strain of 0.00075 in a linearly elastic material. Young’s modulus is:
A. 100 GPa
B. 150 GPa
C. 200 GPa
D. 250 GPa
Answer: C. 200 GPa
Explanation:
E=σ/ϵ
=150/0.00075=200,000″ ” MPa=200″ ” GPa

Numerical
Q89. Which of the following statements about ductility is correct?
A. It is measured only by hardness
B. Percentage elongation can be used as an indicator of ductility
C. It means resistance to indentation
D. It means resistance to creep only
Answer: B. Percentage elongation can be used as an indicator of ductility
Explanation: Percentage elongation and percentage reduction in area are commonly used measures of ductility.

Q90. Which of the following statements about toughness is correct?
A. Toughness is identical to hardness
B. Toughness concerns energy absorption before fracture
C. Toughness means only electrical conductivity
D. Toughness means zero deformation
Answer: B. Toughness concerns energy absorption before fracture
Explanation: Toughness represents the capacity to absorb energy and deform before fracture.

Q91. Which of the following statements about hardness is correct?
A. Hardness is resistance to localized deformation
B. Hardness means ductility
C. Hardness means elastic recovery only
D. Hardness means creep rate
Answer: A. Hardness is resistance to localized deformation
Explanation: Indentation hardness tests measure resistance to localized permanent deformation.

Q92. Which statement about fatigue is correct?
A. Fatigue can occur under repeated stresses
B. Fatigue occurs only above the melting point
C. Fatigue is identical to creep
D. Fatigue occurs only under static loading
Answer: A. Fatigue can occur under repeated stresses
Explanation: Fatigue is progressive damage resulting from cyclic or fluctuating stresses.

Q93. Which statement about creep is correct?
A. It is time-dependent deformation
B. It is always instantaneous
C. It is identical to hardness
D. It requires no load
Answer: A. It is time-dependent deformation
Explanation: Creep is the progressive deformation of a material with time under sustained stress, especially at elevated temperature.

Q94. Which property is most desirable for a material used in a cable or wire?
A. Ductility
B. Brittleness
C. Very low tensile strength
D. Very high brittleness
Answer: A. Ductility
Explanation: Wire manufacturing involves drawing, which requires substantial plastic deformation without fracture.

Q95. Which property is particularly desirable in a material used for pressure vessels?
A. Adequate strength and toughness
B. Extreme brittleness
C. Very low ductility
D. Zero fatigue resistance
Answer: A. Adequate strength and toughness
Explanation: Pressure vessels must safely withstand pressure and potential service loads without catastrophic fracture.

Q96. Which property is particularly important for a machine bed?
A. Stiffness
B. Extreme ductility
C. High malleability only
D. Low strength
Answer: A. Stiffness
Explanation: Machine beds must resist deformation and maintain alignment during operation.

Q97. Which of the following is a common cause of stress concentration?
A. Keyway
B. Smooth uniform section
C. Large fillet radius
D. Uniform straight surface
Answer: A. Keyway
Explanation: Keyways create geometric discontinuities and can produce local stress concentration.

Q98. Which of the following is generally used to reduce stress concentration?
A. Sharp notch
B. Fillet
C. Crack
D. Sudden section change
Answer: B. Fillet
Explanation: A properly designed fillet provides a smoother transition and reduces the severity of stress concentration.

Q99. Which statement correctly distinguishes elasticity and plasticity?
A. Elasticity produces permanent deformation; plasticity produces recovery
B. Elasticity is recoverable deformation; plasticity is permanent deformation
C. Both mean exactly the same thing
D. Neither involves deformation
Answer: B. Elasticity is recoverable deformation; plasticity is permanent deformation
Explanation: Elastic deformation disappears substantially after unloading, while plastic deformation remains.
Q100. Which combination is correctly matched?

A. Ductility — ability to absorb impact energy only
B. Hardness — resistance to indentation
C. Creep — repeated cyclic loading only
D. Fatigue — time-dependent deformation under sustained load
Answer: B. Hardness — resistance to indentation
Explanation: Hardness is associated with resistance to localized deformation such as indentation. Fatigue concerns cyclic loading, while creep is time-dependent deformation under sustained stress.

CHAPTER 3 — EXAM REVISION BOX

⭐ Remember These

Stress = Load / Area

Strain = Change in dimension / Original dimension

Young’s Modulus = Stress / Strain

Ductility → Wire drawing

Malleability → Sheet forming

Hardness → Indentation resistance

Toughness → Energy absorption before fracture

Resilience → Elastic energy absorption

Stiffness → Resistance to elastic deformation

Fatigue → Repeated/fluctuating stress

Creep → Time-dependent deformation

Brinell → Ball indenter

Rockwell → Indentation depth

Vickers → Diamond pyramid

Charpy/Izod → Impact testing

Stress concentration → Holes, keyways, notches, sharp corners

CHAPTER 4 — METAL TESTING & TESTING MACHINES

4.1 Introduction
Metal testing is the systematic examination of metals and engineering materials to determine their mechanical properties, physical characteristics, defects, quality and suitability for a particular application.
In Workshop Technology and Manufacturing Processes, testing is important because the material selected for a component must be capable of safely performing under the expected service conditions.
For example:
Shafts → tensile, torsion and fatigue considerations
Pressure vessels → tensile, toughness and NDT
Gears → hardness, wear and fatigue
Springs → tensile, fatigue and resilience
Welded components → tensile and NDT
Machine tools → hardness, strength and dimensional accuracy
4.2 Classification of Material Tests
Material testing can broadly be classified into:

Destructive Testing (DT)
In destructive testing, the specimen is damaged or destroyed during the test.
Examples:
Tensile test
Compression test
Impact test
Torsion test
Fatigue test
Bend test
Non-Destructive Testing (NDT)
In NDT, the component is inspected without causing significant damage to its serviceability.
Examples:
Visual testing
Liquid penetrant testing
Magnetic particle testing
Ultrasonic testing
Radiographic testing
4.3 Destructive Testing
Definition
A destructive test is a test in which the specimen undergoes permanent deformation, damage or fracture during testing.
Main Purpose
To determine properties such as:
Yield strength
Ultimate tensile strength
Ductility
Toughness
Elongation
Reduction in area
Fatigue behaviour
4.4 Non-Destructive Testing
Definition
Non-destructive testing (NDT) is a group of inspection methods used to detect surface or internal discontinuities without significantly damaging the component.
Advantages
Component can often remain in service
Defects can be detected without destroying the part
Useful for quality control
Useful for weld inspection
Useful for detecting hidden defects
4.5 Tensile Test
The tensile test is one of the most important mechanical tests performed on engineering materials.
It determines properties such as:
Yield strength
Ultimate tensile strength
Percentage elongation
Percentage reduction in area
Young’s modulus, within the appropriate elastic range
4.6 Universal Testing Machine
A Universal Testing Machine (UTM) is a machine used to perform several mechanical tests by applying controlled loads to specimens.
Depending on its configuration, a UTM can be used for:
Tensile testing
Compression testing
Bending testing
Shear testing
The machine generally includes:
Loading system
Grips/fixtures
Load-measuring system
Specimen holding arrangement
Control and recording system
4.7 Tensile Test Specimen
A standard tensile specimen generally consists of:
Grip ends
Gauge length
Reduced section
The reduced section is intended to provide a controlled region in which deformation occurs.
4.8 Gauge Length
Definition
The gauge length is the specified length over which elongation is measured during a tensile test.
Initial gauge length is usually represented by:
L_0

Final gauge length after fracture is represented by:
L_f
4.9 Tensile Test Results
A tensile test can provide:

Yield strength
Stress associated with the onset of specified plastic deformation.
Ultimate tensile strength
Maximum engineering tensile stress.
Percentage elongation
%EL=(L_f-L_0)/L_0 ×100
Percentage reduction in area
%RA=(A_0-A_f)/A_0 ×100
4.10 Engineering Stress-Strain Curve
A typical tensile test produces an engineering stress-strain curve.
Important regions/points include:
Proportional limit
Elastic limit
Yield region
Strain-hardening region
Ultimate tensile strength
Necking
Fracture
The exact appearance varies with the material.
4.11 Proportional Region
In the proportional region:
σ∝ϵ

Therefore:
σ=Eϵ

The slope of the linear portion of the engineering stress-strain curve represents Young’s modulus.
4.12 Yielding
Yielding represents the onset of significant plastic deformation.
Some materials, particularly certain low-carbon steels under appropriate conditions, may show a distinct upper and lower yield point.
Other materials do not show a sharply defined yield point.
4.13 Strain Hardening
After yielding, some ductile metals become stronger as plastic deformation continues.
This phenomenon is called:
Strain hardening or work hardening.
4.14 Necking
After the maximum engineering stress is reached in a conventional tensile test of a ductile specimen, localized reduction in cross-sectional area may begin.
This is called:
Necking.
The specimen eventually fractures.
4.15 Compression Test
A compression test determines the behavior of a material under compressive loading.
It is particularly useful for materials such as:
Cast iron
Concrete
Ceramics
Certain polymers
Materials that are difficult to test in tension
Important Point
Ductile metals can undergo large compressive deformation without a clear fracture, making interpretation different from tensile testing.
4.16 Compression Testing Machine
A compression test may be performed using:
Universal Testing Machine
Dedicated compression testing machine
The specimen is placed between compression platens and subjected to increasing compressive load.
4.17 Compression Stress
Average compressive stress can be expressed as:
σ_c=P/A

where:
P= compressive load
A= relevant cross-sectional area
4.18 Shear Test
A shear test determines the resistance of a material to shear loading.
The basic average shear stress relationship is:
τ=P/A

depending on the test configuration.
Shear testing is useful for evaluating:
Riveted joints
Bolted joints
Welded joints
Pins
Fasteners
Materials subjected to direct shear
4.19 Torsion Test
The torsion test determines the behavior of a material under twisting.
It is especially important for:
Shafts
Axles
Drive components
Transmission elements
Important properties can include:
Torsional strength
Shear modulus
Angle of twist behavior
Torsional failure characteristics
4.20 Torsion Testing Machine
A torsion testing machine applies a controlled torque to a specimen and measures the resulting angular deformation.
The relationship between torque and angle of twist can be used to evaluate torsional behaviour.
4.21 Impact Test
Impact testing determines the ability of a material to absorb energy under sudden loading.
Two widely used impact tests are:
Charpy test
Izod test
4.22 Charpy Impact Test
In the Charpy test, a notched specimen is supported horizontally, and a pendulum strikes the specimen.
The absorbed impact energy is determined from the energy lost by the pendulum.
Key Point
Charpy → Horizontal specimen
4.23 Izod Impact Test
In the Izod test, the notched specimen is generally held vertically as a cantilever, and the pendulum strikes it.
Key Point
Izod → Vertical specimen
4.24 Importance of the Notch
A notch acts as a stress concentration.
The notch helps create a controlled location for crack initiation and allows comparison of the material’s resistance to impact fracture.
4.25 Impact Energy
Impact energy is the energy absorbed by the specimen during fracture under impact loading.
A higher absorbed impact energy generally indicates greater resistance to sudden fracture under the specified test conditions.
4.26 Hardness Testing
Hardness testing determines resistance to localized deformation, generally by indentation or related methods.
Major hardness tests include:
Brinell
Rockwell
Vickers
4.27 Brinell Hardness Test
The Brinell test uses a spherical indenter to produce an indentation.
The hardness number is related to the applied load and the size of the indentation.
Important
Brinell → Ball/Spherical indenter
4.28 Brinell Hardness Number
The Brinell hardness number is based on:
Applied load
Diameter of indenter
Diameter of indentation
The indentation diameter is measured after the test.
4.29 Advantages of Brinell Test
Suitable for many bulk metallic materials
Useful for relatively coarse or heterogeneous materials
Large indentation can provide a representative measurement
Limitation
The relatively large indentation may make the test unsuitable for very thin or finished surfaces where indentation damage is unacceptable.
4.30 Rockwell Hardness Test
The Rockwell test determines hardness from the depth of penetration of an indenter under specified loads.
Major Advantage
It is rapid and convenient for production inspection.
4.31 Rockwell Indenters
Depending on the Rockwell scale, indenters can include:
Diamond cone
Hardened steel ball
Carbide ball
The selected indenter and load depend on the particular Rockwell scale.
4.32 Vickers Hardness Test
The Vickers test uses a diamond pyramid indenter.
The two diagonals of the indentation are measured and used to determine the Vickers hardness value.
Important
Vickers → Diamond pyramid
4.33 Advantages of Vickers Test
Can be used over a wide hardness range
Suitable for small areas when properly prepared
Useful for thin sections and microhardness applications with suitable loads
Uses the same basic geometric indenter principle across its scales
4.34 Fatigue Test
Fatigue testing evaluates a material’s behavior under repeated or fluctuating stress.
The specimen is subjected to cyclic loading until:
Failure occurs, or
A specified number of cycles is reached.
4.35 S-N Curve
The relationship between cyclic stress amplitude and number of cycles to failure is commonly represented by an:
S-N curve
where:
S = stress amplitude
N = number of cycles to failure
It is also called a Wohler curve.

4.36 Fatigue Failure
Fatigue failure can occur at stress levels significantly below the static tensile strength.
Typical stages include:
Crack initiation
Crack propagation
Final fracture
4.37 Creep Test
A creep test determines the deformation of a material with time under sustained stress, usually at a controlled elevated temperature.
Important parameters include:
Stress
Temperature
Time
Strain
4.38 Creep Curve
A typical creep curve has three stages:
Stage I — Primary Creep
Creep rate decreases with time.
Stage II — Secondary Creep
Creep rate is approximately steady.
Stage III — Tertiary Creep
Creep rate accelerates, often leading to rupture.
4.39 Non-Destructive Testing — Major Methods
The major NDT methods are:
Visual Testing — VT
Liquid Penetrant Testing — PT
Magnetic Particle Testing — MT
Ultrasonic Testing — UT
Radiographic Testing — RT
4.40 Visual Testing
Visual testing is the simplest NDT method.
It can detect visible defects such as:
Surface cracks
Undercuts
Corrosion
Poor weld appearance
Dimensional abnormalities
4.41 Liquid Penetrant Testing
Liquid penetrant testing is used primarily for detecting surface-breaking discontinuities.
Basic Procedure
Clean the surface.
Apply penetrant.
Allow penetration time.
Remove excess penetrant.
Apply developer.
Inspect indications.
Important
It can be used on many non-porous materials, not only ferromagnetic materials.
4.42 Magnetic Particle Testing
Magnetic particle testing is used for detecting surface and near-surface discontinuities in ferromagnetic materials.
The component is magnetized and magnetic particles are applied.
Defects disturb the magnetic field and produce visible particle accumulations.
Important
MT → Ferromagnetic materials
4.43 Ultrasonic Testing
Ultrasonic testing uses high-frequency sound waves to detect internal and surface-connected discontinuities.
It can be used to detect:
Cracks
Inclusions
Lack of fusion
Internal discontinuities
Thickness variations
4.44 Principle of Ultrasonic Testing
An ultrasonic transducer sends high-frequency sound waves into the component.
When waves encounter an interface or discontinuity, part of the energy is reflected.
The reflected signal can be analyzed to determine information about the defect.

4.45 Radiographic Testing
Radiographic testing uses penetrating radiation, commonly X-rays or gamma rays, to produce an image showing internal variations in the component.
It is commonly used for inspection of:
Welds
Castings
Pressure-containing components
4.46 Advantages of Radiography
Radiography can reveal certain internal discontinuities and provides a permanent image/record when conventional film radiography is used.
Limitation
Radiographic testing involves radiation hazards and requires appropriate safety controls.
4.47 Selection of NDT Method
The appropriate NDT method depends on:
Material
Type of defect
Defect location
Component geometry
Thickness
Accessibility
Required sensitivity
Safety considerations
4.48 Weld Testing
Welds can be inspected using:
Visual testing
Liquid penetrant testing
Magnetic particle testing
Ultrasonic testing
Radiographic testing
The method selected depends on the weld material, geometry and suspected defect type.
4.49 Destructive vs Non-Destructive Testing
Destructive Testing Non-Destructive Testing
Specimen may be damaged/destroyed Component is generally preserved
Gives mechanical properties Mainly detects discontinuities
Tensile test Ultrasonic test
Compression test Radiography
Impact test Liquid penetrant
Torsion test Magnetic particle
Fatigue test Visual inspection

4.50 Key Examination Points
Remember:
Tensile Test → Strength + Ductility
UTM → Tensile/Compression/Bending and related tests
Charpy → Horizontal specimen
Izod → Vertical cantilever specimen
Brinell → Spherical indenter
Rockwell → Depth of indentation
Vickers → Diamond pyramid
Fatigue → Cyclic loading
S-N Curve → Stress vs Number of cycles
Creep → Time-dependent deformation
PT → Surface-breaking defects
MT → Ferromagnetic materials
UT → High-frequency sound waves
Q1. The main purpose of material testing is to determine:
A. Only colour
B. Mechanical properties and suitability
C. Only weight
D. Only electrical resistance
Answer: B. Mechanical properties and suitability
Explanation: Material testing helps determine properties and performance characteristics needed for engineering applications.
Q2. Which of the following is a destructive test?
A. Visual inspection
B. Tensile test
C. Ultrasonic test
D. Liquid penetrant test
Answer: B. Tensile test
Explanation: In a tensile test, the specimen is normally permanently deformed and eventually fractured.
Q3. Which is a non-destructive test?
A. Tensile test
B. Impact test
C. Ultrasonic testing
D. Compression test
Answer: C. Ultrasonic testing
Explanation: Ultrasonic testing detects discontinuities without significantly damaging the component.
Q4. A Universal Testing Machine can commonly perform:
A. Only hardness testing
B. Tensile and compression tests
C. Only chemical analysis
D. Only radiography
Answer: B. Tensile and compression tests
Explanation: A UTM can be configured for several mechanical tests including tensile, compression and bending tests.
Q5. The elongation of a tensile specimen is measured over its:
A. Head
B. Grip
C. Gauge length
D. Shoulder only
Answer: C. Gauge length
Explanation: Gauge length is the specified length over which elongation is measured.
Q6. The maximum engineering stress in a tensile test is called:
A. Yield strength
B. Ultimate tensile strength
C. Proof stress
D. Shear strength
Answer: B. Ultimate tensile strength
Explanation: UTS corresponds to the maximum engineering stress reached during the tensile test.
Q7. Which test is primarily used to determine impact toughness?
A. Charpy test
B. Brinell test
C. Vickers test
D. Rockwell test
Answer: A. Charpy test
Explanation: The Charpy test measures energy absorbed by a specimen under impact loading.
Q8. In the Charpy impact test, the specimen is generally:
A. Held vertically as a cantilever
B. Supported horizontally
C. Suspended freely
D. Rotated continuously
Answer: B. Supported horizontally
Explanation: A standard Charpy specimen is supported horizontally and struck by a pendulum.
Q9. In the Izod test, the specimen is generally:
A. Horizontally simply supported
B. Vertically supported as a cantilever
C. Freely suspended
D. Placed under compression
Answer: B. Vertically supported as a cantilever
Explanation: The Izod specimen is held vertically and struck by the pendulum.
Q10. The notch in an impact-test specimen mainly acts as:
A. A cooling device
B. A stress concentrator
C. A lubricant reservoir
D. A measuring scale
Answer: B. A stress concentrator
Explanation: The notch creates a controlled region of high local stress where fracture can initiate.
Q11. Brinell hardness testing uses:
A. A spherical indenter
B. A diamond cone only
C. A pendulum
D. Ultrasonic waves
Answer: A. A spherical indenter
Explanation: The Brinell method uses a ball-type indenter and measures the resulting indentation.
Q12. Rockwell hardness testing is primarily based on:
A. Indentation depth
B. Tensile elongation
C. Impact energy
D. Reduction in area
Answer: A. Indentation depth
Explanation: Rockwell hardness is determined from the depth of penetration under specified loading conditions.
Q13. The Vickers hardness test uses:
A. Steel ball
B. Diamond pyramid
C. Pendulum
D. Cylindrical roller
Answer: B. Diamond pyramid
Explanation: The Vickers indenter is a diamond pyramid, traditionally with a square base.
Q14. Which test is particularly suitable for determining hardness rapidly in production environments?
A. Rockwell test
B. Tensile test
C. Impact test
D. Creep test
Answer: A. Rockwell test
Explanation: Rockwell testing is relatively rapid because hardness is obtained directly from indentation depth.
Q15. Which test is commonly used for detecting surface-breaking cracks on a non-porous component?
A. Liquid penetrant testing
B. Tensile testing
C. Compression testing
D. Torsion testing
Answer: A. Liquid penetrant testing
Explanation: Penetrant testing is designed to reveal surface-breaking discontinuities in suitable non-porous materials.
Q16. Magnetic particle testing is primarily applicable to:
A. Ferromagnetic materials
B. All plastics
C. Wood only
D. Glass only
Answer: A. Ferromagnetic materials
Explanation: The method depends on magnetization and magnetic flux leakage.

Q17. Ultrasonic testing uses:
A. High-frequency sound waves
B. Visible light only
C. Magnetic particles only
D. X-rays only
Answer: A. High-frequency sound waves
Explanation: UT introduces high-frequency acoustic waves into the component and analyzes reflected signals.
Q18. Radiographic testing commonly uses:
A. X-rays or gamma rays
B. Water pressure
C. Magnetic particles
D. Mechanical indentation
Answer: A. X-rays or gamma rays
Explanation: Radiography uses penetrating radiation to produce an image showing internal variations.
Q19. Which NDT method is particularly useful for detecting internal discontinuities using reflected sound waves?
A. Ultrasonic testing
B. Visual testing
C. Liquid penetrant testing
D. Magnetic particle testing
Answer: A. Ultrasonic testing
Explanation: UT detects discontinuities through reflections of high-frequency sound waves.
Q20. The S-N curve is associated with:
A. Fatigue testing
B. Hardness testing
C. Compression testing
D. Brinell testing
Answer: A. Fatigue testing
Explanation: An S-N curve relates cyclic stress level to the number of cycles to failure
Q21. In an S-N curve, N generally represents:
A. Newton
B. Number of cycles
C. Normal stress
D. Notch depth
Answer: B. Number of cycles
Explanation: In fatigue testing, N represents the number of loading cycles.
Q22. Creep is:
A. Instantaneous elastic deformation only
B. Time-dependent deformation under sustained stress
C. Impact fracture only
D. Hardness measurement
Answer: B. Time-dependent deformation under sustained stress
Explanation: Creep develops progressively with time under sustained loading, particularly at elevated temperatures.
Q23. During secondary creep, the creep rate is approximately:
A. Constant
B. Infinite
C. Always zero
D. Increasing rapidly
Answer: A. Constant
Explanation: Secondary creep is characterized approximately by a steady creep rate.

Q24. During tertiary creep:
A. Creep rate generally accelerates
B. Creep stops completely
C. Stress becomes zero
D. The specimen becomes perfectly elastic
Answer: A. Creep rate generally accelerates
Explanation: Tertiary creep is associated with accelerating deformation and often culminates in rupture.
Q25. Which test determines a material’s behavior under twisting?
A. Torsion test
B. Brinell test
C. Charpy test
D. Radiographic test
Answer: A. Torsion test
Explanation: A torsion test applies torque and measures the resulting angular deformation and torsional response.
Q26. The tensile test is mainly performed to determine:
A. Melting point
B. Tensile properties
C. Electrical resistance
D. Thermal conductivity
Answer: B. Tensile properties
Explanation: A tensile test provides information about yield strength, ultimate tensile strength, elongation, reduction in area and elastic behavior.
Q27. Which property can be determined from the percentage elongation obtained in a tensile test?
A. Ductility
B. Hardness
C. Thermal conductivity
D. Density
Answer: A. Ductility
Explanation: Percentage elongation is one of the common measures of ductility.
Q28. The percentage reduction in area in a tensile test is calculated using:
A. Original and final cross-sectional areas
B. Original and final lengths
C. Load and time
D. Stress and temperature
Answer: A. Original and final cross-sectional areas
Explanation:
%RA=(A_0-A_f)/A_0 ×100

where A_0is the original area and A_fis the final area.
Q29. The slope of the initial straight portion of a stress-strain curve represents:
A. Toughness
B. Young’s modulus
C. Hardness
D. Fatigue strength
Answer: B. Young’s modulus
Explanation: In the linear elastic region:
E=σ/ϵ

Thus, the slope is Young’s modulus.
Q30. In a tensile test of a ductile metal, necking normally begins:
A. Before loading
B. At or after the maximum engineering stress
C. At zero stress
D. Before the elastic region
Answer: B. At or after the maximum engineering stress
Explanation: Localized necking generally begins after the maximum engineering stress, i.e., after UTS has been reached.
Q31. Which machine is commonly used for tensile testing of metallic specimens?
A. Universal Testing Machine
B. Lathe machine
C. Drilling machine
D. Shaper
Answer: A. Universal Testing Machine
Explanation: A UTM is designed to apply controlled loads for tests such as tension and compression.
Q32. The load applied during a tensile test is measured by the:
A. Load-measuring system of the testing machine
B. Vernier caliper
C. Micrometer only
D. Thermometer
Answer: A. Load-measuring system of the testing machine
Explanation: The testing machine incorporates a load cell or other calibrated load-measuring mechanism.

Q33. A tensile specimen normally has a reduced section mainly to:
A. Control the region of deformation
B. Increase its weight
C. Prevent any deformation
D. Increase its temperature
Answer: A. Control the region of deformation
Explanation: The reduced gauge section promotes deformation in a defined region and facilitates measurement.
Q34. Which of the following is NOT normally obtained directly from a tensile test?
A. Ultimate tensile strength
B. Percentage elongation
C. Reduction in area
D. Melting point
Answer: D. Melting point
Explanation: Melting point is a thermal property and is not determined by a standard tensile test.
Q35. The area under the complete stress-strain curve up to fracture is associated with:
A. Toughness
B. Hardness
C. Stiffness only
D. Yield strength only
Answer: A. Toughness
Explanation: It represents the energy absorbed per unit volume before fracture.
Q36. The area under the elastic portion of the stress-strain curve represents:
A. Modulus of resilience
B. Ultimate strength
C. Hardness number
D. Fatigue limit
Answer: A. Modulus of resilience
Explanation: The area under the elastic region represents elastic strain energy stored per unit volume.
Q37. A material that undergoes considerable plastic deformation before fracture is:
A. Ductile
B. Brittle
C. Perfectly rigid
D. Non-deformable
Answer: A. Ductile
Explanation: Ductility is the ability to undergo significant plastic deformation in tension before fracture.
Q38. A brittle material generally shows:
A. Large plastic deformation before fracture
B. Little plastic deformation before fracture
C. Unlimited elongation
D. No fracture
Answer: B. Little plastic deformation before fracture
Explanation: Brittle materials generally fracture with relatively little plastic deformation.
Q39. Compression testing is particularly useful for evaluating:
A. Compressive behavior
B. Electrical conductivity
C. Melting temperature
D. Magnetic permeability only
Answer: A. Compressive behavior
Explanation: Compression tests evaluate the response of a material to compressive loading.
Q40. Which material is commonly evaluated by compression testing because tensile testing may be less representative of its service behavior?
A. Concrete
B. Copper wire only
C. Spring wire only
D. Aluminium foil only
Answer: A. Concrete
Explanation: Concrete has high compressive strength but comparatively low tensile strength, making compression testing particularly important.
Q41. A specimen under compression generally experiences:
A. Reduction in length
B. Increase in length
C. Only twisting
D. No deformation
Answer: A. Reduction in length
Explanation: Compressive loading tends to shorten the specimen.
Q42. The primary purpose of a torsion test is to determine:
A. Behavior under twisting
B. Resistance to indentation
C. Impact energy
D. Thermal expansion
Answer: A. Behavior under twisting
Explanation: Torsion testing determines the response of a material to applied torque.
Q43. Torsion testing is particularly important for:
A. Shafts
B. Flat glass windows
C. Bricks only
D. Paint coatings only
Answer: A. Shafts
Explanation: Shafts transmit torque and therefore must have adequate torsional strength and stiffness.
Q44. The angle through which a torsion specimen rotates under applied torque is called:
A. Angle of twist
B. Angle of friction
C. Angle of impact
D. Angle of hardness
Answer: A. Angle of twist
Explanation: The angular deformation caused by torque is called the angle of twist.
Q45. The main objective of an impact test is to determine:
A. Energy absorption under sudden loading
B. Melting point
C. Thermal conductivity
D. Electrical resistance
Answer: A. Energy absorption under sudden loading
Explanation: Impact tests evaluate resistance to fracture under sudden loading.
Q46. Which of the following is an impact testing machine/test?
A. Charpy
B. Brinell
C. Rockwell
D. Vickers
Answer: A. Charpy
Explanation: Charpy is an impact test, whereas Brinell, Rockwell and Vickers are hardness tests.
Q47. Which pair consists entirely of impact tests?
A. Charpy and Izod
B. Brinell and Vickers
C. Rockwell and Brinell
D. Vickers and Izod
Answer: A. Charpy and Izod
Explanation: Both Charpy and Izod are pendulum impact tests.
Q48. In a Charpy test, the specimen is generally:
A. Simply supported
B. Held as a vertical cantilever
C. Clamped at both ends
D. Held without support
Answer: A. Simply supported
Explanation: A standard Charpy specimen rests horizontally on supports and is struck by the pendulum.
Q49. In an Izod test, the specimen is:
A. Held as a cantilever
B. Simply supported at both ends
C. Freely suspended
D. Placed horizontally without support
Answer: A. Held as a cantilever
Explanation: The Izod specimen is fixed vertically at one end.
Q50. The energy absorbed by an impact specimen is determined from:
A. Loss of pendulum energy
B. Change in colour
C. Increase in temperature only
D. Weight of the specimen alone
Answer: A. Loss of pendulum energy
Explanation: The difference between the pendulum’s energy before and after striking the specimen corresponds to the energy absorbed, accounting for machine losses as applicable.
Q51. Which hardness test uses the diameter of an indentation as an important measurement?
A. Brinell
B. Rockwell
C. Ultrasonic
D. Radiographic
Answer: A. Brinell
Explanation: Brinell hardness is determined from the load and the diameter of the indentation produced by the spherical indenter.
Q52. In the Rockwell test, the hardness value is mainly related to:
A. Depth of penetration
B. Pendulum height
C. Specimen elongation
D. Reduction in area
Answer: A. Depth of penetration
Explanation: Rockwell hardness is based on indentation depth under specified minor and major loads.
Q53. The Vickers hardness number is determined from:
A. Indentation diagonals and applied load
B. Tensile elongation only
C. Impact energy only
D. Pendulum velocity only
Answer: A. Indentation diagonals and applied load
Explanation: The Vickers test measures the diagonals of the diamond-pyramid indentation.
Q54. Which hardness test is particularly useful for very small areas when appropriate loads are selected?
A. Vickers
B. Charpy
C. Izod
D. Compression
Answer: A. Vickers
Explanation: Vickers testing can be performed with relatively small loads and is widely used in microhardness applications.
Q55. Which of the following is a major advantage of Rockwell hardness testing?
A. Rapid measurement
B. Requires complete fracture
C. Requires tensile specimen
D. Measures impact energy
Answer: A. Rapid measurement
Explanation: Rockwell testing is widely used for quick production inspection.
Q56. Fatigue testing involves:
A. Repeated or fluctuating loading
B. Only one static load
C. Only thermal loading
D. Only hydrostatic pressure
Answer: A. Repeated or fluctuating loading
Explanation: Fatigue damage develops under cyclic stress variations.
Q57. Fatigue failure can occur:
A. Only above UTS
B. At stress levels below static tensile strength
C. Only at melting temperature
D. Only under compression
Answer: B. At stress levels below static tensile strength
Explanation: Repeated loading can initiate and propagate cracks even when individual stress cycles are below the material’s static strength.
Q58. A fatigue crack usually begins at:
A. A region of stress concentration or surface defect
B. The centre of a perfectly uniform specimen only
C. A region of zero stress
D. The measuring scale
Answer: A. A region of stress concentration or surface defect
Explanation: Notches, scratches, holes and other discontinuities can promote fatigue crack initiation.
Q59. The S-N curve is also known as:
A. Wöhler curve
B. Brinell curve
C. Creep curve
D. Hardness curve
Answer: A. Wöhler curve
Explanation: The S-N relationship is historically associated with August Wöhler.
Q60. In an S-N curve, S generally represents:
A. Stress
B. Strain only
C. Surface area
D. Speed
Answer: A. Stress
Explanation: S represents the selected cyclic stress measure, commonly stress amplitude.
Q61. Which test is used to study time-dependent deformation?
A. Creep test
B. Brinell test
C. Charpy test
D. Tensile hardness test
Answer: A. Creep test
Explanation: Creep testing measures progressive deformation under sustained stress with time.
Q62. Creep is particularly important in:
A. High-temperature components
B. Components with no load
C. Room-temperature unloaded parts only
D. Measuring instruments only
Answer: A. High-temperature components
Explanation: Elevated temperature significantly accelerates creep in many engineering materials.
Q63. Which stage of creep has a decreasing creep rate?
A. Primary creep
B. Secondary creep
C. Tertiary creep
D. Fracture stage only
Answer: A. Primary creep
Explanation: During primary creep, the creep rate decreases with time.

Q64. Which stage of creep has approximately constant creep rate?
A. Primary
B. Secondary
C. Tertiary
D. Fracture
Answer: B. Secondary
Explanation: Secondary creep is characterized by an approximately steady-state creep rate.
Q65. Which stage of creep generally precedes rupture?
A. Tertiary creep
B. Primary creep
C. Elastic region
D. Proportional region
Answer: A. Tertiary creep
Explanation: Tertiary creep involves accelerating deformation and commonly ends in rupture.
Q66. Visual testing can detect:
A. Visible surface defects
B. Deep internal defects in every case
C. Atomic-level defects
D. All subsurface defects
Answer: A. Visible surface defects
Explanation: Visual inspection is mainly used for accessible surface conditions and visible discontinuities.
Q67. Liquid penetrant testing is primarily used to detect:
A. Surface-breaking discontinuities
B. Deep internal defects only
C. Bulk density
D. Young’s modulus
Answer: A. Surface-breaking discontinuities
Explanation: Penetrant enters surface-connected openings and is subsequently revealed by the developer.
Q68. The first important step in liquid penetrant testing is generally:
A. Surface cleaning
B. Applying developer immediately
C. Applying magnetic field
D. Fracturing the specimen
Answer: A. Surface cleaning
Explanation: The surface must be properly cleaned so the penetrant can enter relevant surface-breaking discontinuities.
Q69. In liquid penetrant testing, the developer is used to:
A. Draw penetrant out of discontinuities and make indications visible
B. Magnetize the component
C. Increase tensile strength
D. Produce a fracture
Answer: A. Draw penetrant out of discontinuities and make indications visible
Explanation: Developer creates a contrasting indication by drawing penetrant back to the surface.
Q70. Magnetic particle testing requires the test component to be:
A. Ferromagnetic
B. Transparent
C. Non-metallic only
D. Liquid
Answer: A. Ferromagnetic
Explanation: Magnetization and magnetic flux leakage are fundamental to this method.
Q71. A discontinuity in magnetic particle testing produces:
A. Magnetic flux leakage
B. Thermal expansion only
C. Sound absorption only
D. Electrical insulation only
Answer: A. Magnetic flux leakage
Explanation: A discontinuity disturbs the magnetic field, causing flux leakage where particles can accumulate.
Q72. Ultrasonic testing can be used to detect:
A. Internal discontinuities
B. Only colour variations
C. Only surface paint
D. Only electrical defects
Answer: A. Internal discontinuities
Explanation: Reflected ultrasonic waves can reveal internal defects and interfaces.
Q73. The device that sends and/or receives ultrasonic waves in UT is called:
A. Transducer
B. Pendulum
C. Indenter
D. Extensometer only
Answer: A. Transducer
Explanation: The transducer converts electrical energy to ultrasonic mechanical waves and receives returning signals.
Q74. Radiographic testing is particularly useful for:
A. Examining internal discontinuities
B. Measuring hardness directly
C. Measuring tensile strength directly
D. Measuring elongation directly
Answer: A. Examining internal discontinuities
Explanation: Radiography produces an image based on differential absorption of penetrating radiation.
Q75. Which radiation can be used in industrial radiographic testing?
A. X-rays
B. Visible light only
C. Sound waves
D. Radio waves only
Answer: A. X-rays
Explanation: Industrial radiography commonly uses X-rays and gamma radiation.
Q76. Which NDT method generally requires special radiation-safety precautions?
A. Radiographic testing
B. Visual testing
C. Liquid penetrant testing
D. Magnetic particle testing
Answer: A. Radiographic testing
Explanation: Ionizing radiation can be hazardous and requires controlled areas, shielding and appropriate safety procedures.
Q77. Which NDT method does NOT require the material to be ferromagnetic?
A. Liquid penetrant testing
B. Magnetic particle testing
C. Both require ferromagnetism
D. Neither can inspect metals
Answer: A. Liquid penetrant testing
Explanation: PT can be applied to many non-porous materials, whereas MT requires ferromagnetic material.
Q78. Which test is best associated with detecting surface cracks in a non-ferromagnetic, non-porous material?
A. Liquid penetrant test
B. Magnetic particle test
C. Brinell test
D. Compression test
Answer: A. Liquid penetrant test
Explanation: PT is suitable for surface-breaking defects in many non-porous materials, including non-ferromagnetic alloys.
Q79. Which method is especially useful for detecting subsurface defects in ferromagnetic components?
A. Magnetic particle testing
B. Visual testing only
C. Liquid penetrant only
D. Brinell testing
Answer: A. Magnetic particle testing
Explanation: MT can detect surface and certain near-surface discontinuities in ferromagnetic materials.
Q80. Which NDT method uses sound waves rather than electromagnetic radiation?
A. Ultrasonic testing
B. Radiography
C. Visual testing
D. Magnetic particle testing
Answer: A. Ultrasonic testing
Explanation: UT uses mechanical sound waves, generally at frequencies well above audible sound.
Q81. A steel specimen has an original gauge length of 100 mm and final gauge length of 120 mm. Percentage elongation is:
A. 10%
B. 20%
C. 25%
D. 30%
Answer: B. 20%
Explanation:
%EL=(120-100)/100×100=20%

Numerical
Q82. A specimen has an original area of 500 mm² and final area of 400 mm². Percentage reduction in area is:
A. 10%
B. 15%
C. 20%
D. 25%
Answer: C. 20%
Explanation:
%RA=(500-400)/500×100=20%

Numerical
Q83. A tensile specimen carries a load of 60 kN and has an original area of 300 mm². Engineering stress is:
A. 100 MPa
B. 150 MPa
C. 200 MPa
D. 300 MPa
Answer: C. 200 MPa
Explanation:
σ=(60,000)/300=200″ ” N/mm^2=200″ ” MPa

Numerical
Q84. A material has Young’s modulus of 200 GPa. If stress is 100 MPa, the elastic strain is:
A. 0.0005
B. 0.005
C. 0.05
D. 0.5
Answer: A. 0.0005
Explanation:
ϵ=σ/E=100/200000=0.0005

Numerical
Q85. If the maximum load during a tensile test is 50 kN and original area is 250 mm², UTS is:
A. 100 MPa
B. 150 MPa
C. 200 MPa
D. 250 MPa
Answer: C. 200 MPa
Explanation:
UTS=P_max/A_0
=(50,000)/250=200″ ” MPa

Numerical
Q86. A specimen’s original length is 250 mm and its final length is 275 mm. Percentage elongation is:
A. 5%
B. 10%
C. 15%
D. 20%
Answer: B. 10%
Explanation:
(275-250)/250×100=10%

Numerical
Q87. A specimen’s original area is 800 mm² and final area is 600 mm². Reduction in area is:
A. 10%
B. 20%
C. 25%
D. 30%
Answer: C. 25%
Explanation:
(800-600)/800×100=25%

Numerical
Q88. If the stress is 240 MPa and Young’s modulus is 120 GPa, the strain is:
A. 0.0002
B. 0.001
C. 0.002
D. 0.02
Answer: C. 0.002
Explanation:
120″ ” GPa=120000″ ” MPa
ϵ=240/120000=0.002

Numerical
Q89. A specimen has a final area of 90 mm² and an original area of 100 mm². Percentage reduction in area is:
A. 5%
B. 10%
C. 15%
D. 20%
Answer: B. 10%
Explanation:
(100-90)/100×100=10%

Numerical
Q90. A component has a failure strength of 500 MPa and allowable stress of 100 MPa. Factor of safety is:
A. 2
B. 3
C. 4
D. 5
Answer: D. 5
Explanation:
FOS=500/100=5

Numerical
Q91. Which testing method is most appropriate for determining ultimate tensile strength?
A. Tensile test
B. Brinell test
C. Radiographic test
D. Liquid penetrant test
Answer: A. Tensile test
Explanation: UTS is directly obtained from the maximum engineering stress in a tensile test.
Q92. Which test is primarily used to measure resistance to indentation?
A. Hardness test
B. Tensile test
C. Fatigue test
D. Creep test
Answer: A. Hardness test
Explanation: Hardness tests measure resistance to localized deformation, commonly through indentation.

Q93. Which combination is correctly matched?
A. Brinell — spherical indenter
B. Rockwell — pendulum
C. Charpy — diamond pyramid
D. Vickers — magnetic particles
Answer: A. Brinell — spherical indenter
Explanation: Brinell uses a spherical indenter; Rockwell uses depth measurement, Charpy is an impact test and Vickers uses a diamond pyramid.
Q94. Which combination is correctly matched?
A. Vickers — diamond pyramid
B. Charpy — hardness test
C. Izod — creep test
D. Rockwell — radiography
Answer: A. Vickers — diamond pyramid
Explanation: The Vickers test uses a diamond pyramid indenter.
Q95. Which combination is correctly matched?
A. S-N curve — fatigue
B. Creep curve — hardness
C. Brinell curve — tensile testing
D. Charpy curve — radiography
Answer: A. S-N curve — fatigue
Explanation: S-N curves describe the relationship between cyclic stress and number of cycles to failure.
Q96. Which combination is correctly matched?
A. PT — surface-breaking discontinuities
B. MT — all non-metallic materials
C. UT — indentation hardness
D. RT — tensile elongation
Answer: A. PT — surface-breaking discontinuities
Explanation: Liquid penetrant testing reveals surface-breaking discontinuities in suitable non-porous surfaces.
Q97. Which combination is correctly matched?
A. MT — ferromagnetic materials
B. UT — only transparent materials
C. RT — hardness measurement
D. PT — only ferromagnetic materials
Answer: A. MT — ferromagnetic materials
Explanation: Magnetic particle testing requires a material capable of being magnetized sufficiently for flux leakage to reveal discontinuities.
Q98. Which NDT technique can produce an image of internal discontinuities using penetrating radiation?
A. Radiographic testing
B. Visual testing
C. Magnetic particle testing
D. Liquid penetrant testing
Answer: A. Radiographic testing
Explanation: X-rays or gamma rays pass through the component and produce differential absorption that can reveal internal features.
Q99. Which NDT method uses reflected ultrasonic waves to locate discontinuities?
A. Ultrasonic testing
B. Brinell testing
C. Rockwell testing
D. Liquid penetrant testing
Answer: A. Ultrasonic testing
Explanation: UT evaluates reflected acoustic energy from interfaces and discontinuities.
Q100. Which statement is correct?
A. Destructive testing never damages the specimen
B. NDT is intended to inspect components without significant damage
C. Tensile testing is an NDT method
D. Charpy testing is a hardness test
Answer: B. NDT is intended to inspect components without significant damage
Explanation: NDT methods inspect materials/components while preserving their serviceability, subject to the particular method and inspection process.

CHAPTER 4 — QUICK REVISION
Test Main Purpose
Tensile Strength & ductility
Compression Compressive behavior
Shear Shear strength
Torsion Twisting behavior
Charpy Impact energy
Izod Impact energy
Brinell Hardness
Rockwell Hardness
Vickers Hardness
Fatigue Cyclic loading behavior
Creep Time-dependent deformation
VT Visible defects
PT Surface-breaking defects
MT Surface/near-surface defects in ferromagnetic materials
UT Internal discontinuities using sound waves
RT Internal discontinuities using X-rays/gamma rays

CHAPTER 5 — FOUNDRY TECHNOLOGY & CASTING PROCESSES

5.1 Introduction
Casting is one of the oldest and most important manufacturing processes. In casting, molten metal is poured into a prepared mould cavity having the desired shape. After solidification, the casting is removed from the mould and subjected to finishing operations.
Casting is particularly useful for producing:
Complex shapes
Large components
Components with internal cavities
Components that are difficult to manufacture by machining
Components from metals having relatively low machinability
Examples include:
Engine blocks
Cylinder heads
Pump housings
Machine beds
Pipes and pipe fittings
Flywheels
Gear blanks
Valve bodies
5.2 Definition of Casting
Casting is a manufacturing process in which molten material is introduced into a mould cavity of the required shape and allowed to solidify.
After solidification, the component is removed from the mould.
Basic Casting Sequence
Pattern → Mould → Melting → Pouring → Solidification → Shakeout → Fettling → Inspection
5.3 Basic Principle of Casting
The basic principle involves four major stages:
Step 1 — Preparation of mould
A cavity corresponding to the desired component is prepared.
Step 2 — Melting
The metal is heated above its melting temperature.
Step 3 — Pouring
The molten metal is introduced into the mould cavity.
Step 4 — Solidification
The metal cools and solidifies, taking the shape of the mould cavity.
5.4 Advantages of Casting
Casting offers several important advantages.

Complex shapes
Very complex geometries can be produced.
Large components
Very large components can be manufactured economically.
Internal cavities
Cores can be used to produce internal holes and passages.
Wide material range
Many ferrous and non-ferrous alloys can be cast.
Reduced machining
Near-net-shape castings can reduce subsequent machining.
Economical for suitable production quantities
Casting can be economical for both certain small-batch and mass-production applications depending on the process.
5.5 Limitations of Casting
Some limitations include:
Possible casting defects
Porosity
Shrinkage
Gas defects
Dimensional variations
Surface-finish limitations in some processes
Mould preparation requirements
Metallurgical problems if cooling is not properly controlled
5.6 Classification of Casting Processes
Casting processes can broadly be classified into:
A. Expendable Mould Processes
The mould is normally destroyed to remove the casting.
Examples:
Sand casting
Shell moulding
Investment casting
Lost-foam casting
B. Permanent Mould Processes
The mould is reused for many castings.
Examples:
Gravity die casting
Pressure die casting
Centrifugal casting
5.7 Pattern
A pattern is a replica or representation of the desired casting shape used to form the mould cavity.
The pattern is not necessarily an exact-size replica because allowances may be provided.
5.8 Functions of a Pattern
A pattern is used to:
Produce the mould cavity
Establish the basic shape of the casting
Provide allowances
Provide core prints where required
Facilitate moulding
Help maintain dimensional accuracy
5.9 Pattern Materials
Patterns may be made from:
Wood
Metals
Plastics
Plaster
Wax
Resins
Other suitable materials
5.10 Wooden Patterns
Wood is commonly used for patterns because it is:
Lightweight
Relatively inexpensive
Easy to shape
Easy to repair
Easy to modify
Limitations
Wooden patterns can:
Absorb moisture
Warp
Wear relatively quickly
Require proper seasoning and surface treatment
5.11 Metal Patterns
Metal patterns are generally more durable than wooden patterns.
Common pattern metals include:
Aluminium alloys
Cast iron
Brass
Bronze
Steel
They are useful when:
Large numbers of castings are required
Better durability is needed
Better dimensional stability is required
5.12 Types of Patterns
Important pattern types include:
Single-piece pattern
Split pattern
Match-plate pattern
Cope-and-drag pattern
Loose-piece pattern
Sweep pattern
Skeleton pattern
Segmental pattern
Gated pattern
Follow-board pattern
5.13 Single-Piece Pattern
A single-piece pattern is made as one integral piece.
It is generally used for:
Simple shapes
Small production quantities
Components that can be easily withdrawn from the mould
5.14 Split Pattern
A split pattern consists of two or more parts.
The common two-part pattern is divided along a parting line.
Advantage
It facilitates withdrawal of the pattern from the mould without damaging the mould cavity.
5.15 Match-Plate Pattern
A match-plate pattern has the pattern halves mounted on opposite sides of a plate.
It is commonly used for:
High-production work
Machine moulding
Accurate mould alignment
5.16 Cope and Drag Pattern
In a cope-and-drag arrangement, pattern sections are mounted on separate plates.
It is useful for:
Large castings
Machine moulding
High-production applications
5.17 Sweep Pattern
A sweep pattern consists of a shaped board or template that is rotated around an axis to generate the mould cavity.
It is useful for:
Large circular or symmetrical castings
Large components where a complete pattern would be expensive
5.18 Skeleton Pattern
A skeleton pattern is a framework representing the shape of the casting.
It is generally used for:
Large castings
Simple geometries
Small production quantities
5.19 Gated Pattern
In a gated pattern, several patterns are connected to a common gating system.
This arrangement allows multiple castings to be produced in one mould.
5.20 Pattern Allowances
Pattern allowances are dimensional modifications provided on the pattern to compensate for various effects during casting and moulding.
Major allowances include:
Shrinkage allowance
Machining allowance
Draft allowance
Distortion allowance
Rapping/shake allowance
5.21 Shrinkage Allowance
Most metals shrink during cooling and solidification.
Therefore, the pattern is generally made slightly larger than the desired casting dimensions to compensate for shrinkage.
Important
Pattern size > corresponding final casting size
5.22 Machining Allowance
Additional material is provided on surfaces that will later be machined.
Purpose
It allows removal of:
Surface irregularities
Oxidized material
Dimensional variations
Casting skin
5.23 Draft Allowance
Draft is a small taper provided on vertical surfaces of the pattern.
Purpose
To facilitate easy withdrawal of the pattern from the mould without damaging the mould cavity.
Important
Draft → Easy pattern withdrawal
5.24 Distortion Allowance
Some castings may distort during cooling because different portions contract differently.
The pattern may therefore be intentionally distorted in the opposite direction to compensate.
5.25 Shake Allowance
When a pattern is rapped before removal, the mould cavity can become slightly enlarged.
Therefore, a small negative allowance may be considered to compensate for this effect.
5.26 Moulding Sand
Moulding sand is used to create the mould around the pattern.
Important requirements include:
Refractoriness
Permeability
Strength
Plasticity
Flowability
Collapsibility
Adhesiveness
Cohesiveness
5.27 Refractoriness
Refractoriness is the ability of moulding sand to withstand the high temperature of molten metal without melting or losing its essential properties.
Remember:
Refractoriness → Resistance to high temperature
5.28 Permeability
Permeability is the ability of moulding sand to allow gases and air to pass through it.
Adequate permeability is important for avoiding:
Blowholes
Gas porosity
Other gas-related defects
5.29 Cohesiveness
Cohesiveness is the ability of sand grains to stick to each other.
Good cohesiveness helps the mould retain its shape.
5.30 Adhesiveness
Adhesiveness is the ability of moulding sand to adhere to the surface of the moulding box or other supporting surfaces.
5.31 Plasticity
Plasticity is the ability of moulding sand to deform and reproduce the pattern shape without cracking or breaking.
5.32 Collapsibility
Collapsibility is the ability of moulding sand to break down or yield after solidification of the casting.
Good collapsibility helps:
Casting removal
Reduction of hot tearing
Release of internal stresses
5.33 Green Sand
Green sand is moulding sand used in a moist condition, containing sufficient moisture and binder for moulding.
It does not necessarily mean that the sand is green in colour.
5.34 Dry Sand Mould
A dry sand mould is dried or baked before molten metal is poured.
Compared with ordinary green-sand moulding, drying can provide greater mould strength and dimensional stability for suitable applications.
5.35 Core
A core is a preformed body of material placed inside a mould to create an internal cavity or passage in the casting.
Examples:
Engine cylinder internal cavity
Pipe passage
Valve passage
Internal holes
5.36 Core Prints
Core prints are projections or recesses provided in the pattern and corresponding mould regions to locate and support the core.
Important:
Core print → Supports and locates the core
5.37 Gating System
The gating system is the network of passages through which molten metal flows from the pouring basin into the mould cavity.
Main components can include:
Pouring basin
Sprue
Sprue well
Runner
Ingate
5.38 Pouring Basin
The pouring basin receives molten metal from the ladle and directs it into the sprue.
It helps:
Reduce turbulence
Remove some impurities
Provide a convenient pouring location
5.39 Sprue
A sprue is the vertical passage through which molten metal flows downward from the pouring basin.
In a well-designed system, the sprue is generally tapered to reduce air aspiration and maintain proper flow.
5.40 Runner
The runner is the horizontal or substantially horizontal passage that carries molten metal from the sprue toward one or more ingates.
5.41 Ingate
The ingate is the opening through which molten metal enters the mould cavity from the runner.
5.42 Riser
A riser is a reservoir of molten metal connected to the casting that supplies additional metal during solidification to compensate for shrinkage.
Important:
Riser → Feeds molten metal during solidification
5.43 Functions of a Riser
A properly designed riser helps:
Compensate for solidification shrinkage
Promote directional solidification
Reduce shrinkage cavities
5.44 Chills
A chill is a metallic insert placed in or near a mould cavity to increase the local rate of heat extraction.
Purpose
To promote faster solidification in selected regions.
5.45 Cupola Furnace
The cupola furnace is widely used for melting cast iron in foundries.
It is a vertical cylindrical furnace in which:
Coke acts as fuel
Air is supplied through tuyeres
Metal charge is melted continuously during operation
5.46 Cupola Furnace — Main Components
Important parts include:
Steel shell
Refractory lining
Charging door
Tuyeres
Wind belt
Slag hole
Tap hole
Chimney/stack
Drop bottom
5.47 Tuyeres
Tuyeres are openings through which air is supplied into the cupola furnace.
The supplied air supports combustion.
Remember:
Tuyere → Air supply
5.48 Cupola Fuel
Traditionally, coke is the primary fuel used in a conventional cupola furnace.
5.49 Casting Defects
A casting defect is an undesirable irregularity or imperfection that reduces the quality or usefulness of a casting.
Common defects include:
Blowholes
Porosity
Shrinkage cavity
Misrun
Cold shut
Hot tear
Sand inclusion
Scab
Metal penetration
Mismatch
5.50 Blowholes
Blowholes are cavities caused by trapped gas.
Possible causes include:
Excess moisture
Poor permeability
Excessive gas generation
Inadequate venting
5.51 Shrinkage Cavity
Shrinkage cavity occurs when insufficient liquid metal is available to compensate for volumetric contraction during solidification.
Prevention
Proper riser design
Directional solidification
Proper feeding system
5.52 Misrun
A misrun occurs when molten metal fails to completely fill the mould cavity.
Possible causes:
Low pouring temperature
Slow pouring
Poor fluidity
Thin sections
Inadequate gating
5.53 Cold Shut
A cold shut occurs when two streams of molten metal meet but fail to fuse properly.
It appears as a seam or line on the casting.
5.54 Hot Tear
A hot tear is a crack formed during the late stages of solidification when the metal cannot accommodate contraction because of restraint.
Factors include:
Poor mould/core collapsibility
Restrained contraction
Improper casting design
Thermal stresses
5.55 Sand Inclusion
Sand inclusion occurs when moulding sand becomes incorporated into the casting.
Possible causes:
Weak mould surface
Poor mould handling
Excessive erosion
Turbulent metal flow
5.56 Metal Penetration
Metal penetration occurs when molten metal enters the spaces between sand grains, producing a rough surface.
It can be influenced by:
Mould characteristics
Metal temperature
Sand grain size
Mould strength

5.57 Fettling
Fettling refers to finishing operations performed on a casting after it has been removed from the mould.
Operations may include:
Removal of gates
Removal of risers
Removal of fins
Cleaning
Grinding
Surface finishing
5.58 Shakeout
Shakeout is the process of removing the solidified casting from the mould.
In sand casting, the mould is broken to retrieve the casting.
5.59 Special Casting Processes
Important special casting processes include:
Die casting
Investment casting
Centrifugal casting
Shell moulding
Continuous casting
Lost-foam casting
These processes are selected according to:
Required accuracy
Surface finish
Production volume
Component size
Material
Complexity
5.60 Die Casting
Die casting forces molten metal into a metallic die under pressure.
It is commonly used for high-volume production of relatively small and complex non-ferrous components.
Typical alloys include:
Aluminium alloys
Zinc alloys
Magnesium alloys
5.61 Investment Casting
Investment casting is also known as lost-wax casting.
A wax pattern is coated with refractory material to create the mould.
The wax is subsequently removed before pouring the metal.
Major Advantage
It can produce:
Complex shapes
Fine details
Good dimensional accuracy
Good surface finish
5.62 Centrifugal Casting
In centrifugal casting, molten metal is poured into a rotating mould.
Centrifugal force helps distribute the molten metal against the mould wall.
It is particularly suitable for:
Pipes
Tubes
Cylindrical components
5.63 Shell Moulding
Shell moulding uses a thin shell of resin-bonded sand formed around a heated pattern.
Advantages include:
Good surface finish
Good dimensional accuracy
Reduced machining
Suitable for relatively complex shapes
5.64 Continuous Casting
In continuous casting, molten metal is continuously poured into a mould and withdrawn as a continuously solidifying strand.
Products may include:
Slabs
Billets
Blooms
Continuous casting is widely used in modern metal production.
5.65 Key Revision Table
Term Main Point
Pattern Forms mould cavity
Shrinkage allowance Compensates for contraction
Machining allowance Material for later machining
Draft allowance Easy pattern withdrawal
Core Forms internal cavity
Core print Supports/locates core
Sprue Vertical metal passage
Runner Carries metal toward ingates
Ingate Entry into mould cavity
Riser Feeds metal during solidification
Chill Increases local cooling
Permeability Allows gases to escape
Refractoriness Withstands high temperature
Collapsibility Breaks down after solidification
Cupola Melts cast iron
Tuyere Supplies air
Misrun Incomplete filling
Cold shut Poor fusion of metal streams
Blowhole Gas cavity
Shrinkage cavity Feeding-related void
Fettling Casting finishing
Investment casting Lost-wax process
Die casting Pressure injection into die
Centrifugal casting Rotating mould
Continuous casting Continuous strand production

MCQ 1
Casting is a process in which molten metal is:
A. Rolled into sheets
B. Poured into a mould cavity and solidified
C. Forged under a hammer
D. Drawn through a die
Answer: B. Poured into a mould cavity and solidified
Explanation: Casting produces a component by filling a mould cavity with molten material and allowing it to solidify.
MCQ 2
The main function of a pattern is to:
A. Melt the metal
B. Form the mould cavity
C. Cool the casting
D. Measure hardness
Answer: B. Form the mould cavity
Explanation: The pattern is used to create the desired cavity in the mould.
MCQ 3
Which allowance is provided to compensate for metal contraction during cooling?
A. Draft allowance
B. Machining allowance
C. Shrinkage allowance
D. Distortion allowance
Answer: C. Shrinkage allowance
Explanation: Metals generally contract during solidification and cooling, so pattern dimensions are adjusted accordingly.
MCQ 4
Draft allowance is provided mainly to:
A. Increase hardness
B. Facilitate pattern withdrawal
C. Increase melting temperature
D. Reduce density
Answer: B. Facilitate pattern withdrawal
Explanation: Draft provides taper on surfaces parallel to the direction of pattern withdrawal.
MCQ 5
Which allowance provides extra metal for subsequent machining?
A. Machining allowance
B. Draft allowance
C. Shake allowance
D. Distortion allowance
Answer: A. Machining allowance
Explanation: Extra material is deliberately provided on surfaces that will be machined later.
MCQ 6
A core is mainly used to produce:
A. External colour
B. Internal cavities
C. Surface hardness
D. Metal melting
Answer: B. Internal cavities
Explanation: Cores occupy regions within the mould cavity to create internal holes, passages or cavities.
MCQ 7
Which property of moulding sand allows gases to escape?
A. Cohesiveness
B. Permeability
C. Adhesiveness
D. Plasticity
Answer: B. Permeability
Explanation: Permeability permits gases generated during pouring and solidification to pass through the mould.
MCQ 8
The ability of moulding sand to withstand high temperature is called:
A. Permeability
B. Refractoriness
C. Adhesiveness
D. Collapsibility
Answer: B. Refractoriness
Explanation: Refractoriness is resistance to the high temperature of molten metal.
MCQ 9
The ability of moulding sand to break down after casting solidification is called:
A. Collapsibility
B. Permeability
C. Adhesiveness
D. Fluidity
Answer: A. Collapsibility
Explanation: Good collapsibility helps casting removal and reduces restraint during contraction.
MCQ 10
Which component of the gating system is generally vertical?
A. Runner
B. Sprue
C. Ingate
D. Riser
Answer: B. Sprue
Explanation: The sprue is the vertical passage carrying molten metal downward from the pouring basin.
Q11. A pattern used for producing a simple casting in small quantity is generally:
A. Match-plate pattern
B. Single-piece pattern
C. Gated pattern
D. Cope-and-drag pattern
Answer: B. Single-piece pattern
Explanation: Single-piece patterns are economical and suitable for simple shapes and limited production.
Q12. A split pattern is divided into two or more parts mainly to:
A. Increase melting temperature
B. Facilitate pattern withdrawal
C. Increase hardness
D. Reduce metal density
Answer: B. Facilitate pattern withdrawal
Explanation: Splitting the pattern allows it to be removed from the mould without damaging the cavity.
Q13. A common split pattern is divided along the:
A. Centre line/parting line
B. Sprue
C. Riser
D. Runner
Answer: A. Centre line/parting line
Explanation: The two halves normally meet along the mould parting plane.
Q14. Match-plate patterns are particularly suitable for:
A. Very low production only
B. Machine moulding and mass production
C. Hand forging
D. Welding
Answer: B. Machine moulding and mass production
Explanation: Match-plate patterns provide accurate alignment and are highly suitable for repetitive machine moulding.
Q15. Which pattern consists of a template rotated around an axis?
A. Sweep pattern
B. Split pattern
C. Match-plate pattern
D. Gated pattern
Answer: A. Sweep pattern
Explanation: A sweep pattern generates a mould cavity by rotating a shaped template around a fixed axis.
Q16. Skeleton patterns are particularly useful for:
A. Very small precision components only
B. Large castings of simple shape
C. Mass-produced tiny castings
D. Wire drawing
Answer: B. Large castings of simple shape
Explanation: A skeleton pattern saves pattern material and labour for large, relatively simple shapes.
Q17. A pattern carrying several identical patterns connected to a common gating system is called:
A. Sweep pattern
B. Gated pattern
C. Skeleton pattern
D. Segmental pattern
Answer: B. Gated pattern
Explanation: A gated pattern permits several castings to be produced from one mould.
Q18. Which pattern material is generally lightweight and easy to work?
A. Wood
B. Tungsten
C. Ceramic only
D. Diamond
Answer: A. Wood
Explanation: Wood is widely used because it is inexpensive, lightweight and easy to shape.
Q19. One important disadvantage of wooden patterns is:
A. Excessive electrical conductivity
B. Moisture absorption and dimensional changes
C. Very high melting point
D. Excessive density
Answer: B. Moisture absorption and dimensional changes
Explanation: Wood can absorb moisture and may warp or change dimensions.
Q20. Metal patterns are generally preferred when:
A. Only one casting is required
B. High production quantity is required
C. No accuracy is required
D. The pattern must be disposable
Answer: B. High production quantity is required
Explanation: Metal patterns offer greater durability and dimensional stability.
Q21. Which allowance compensates for the contraction of the casting during cooling?
A. Draft
B. Shrinkage
C. Machining
D. Shake
Answer: B. Shrinkage
Explanation: The pattern is made larger to compensate for metal contraction.
Q22. The machining allowance is provided on:
A. All surfaces regardless of machining
B. Surfaces that will be machined
C. Only internal cavities
D. Only the sprue
Answer: B. Surfaces that will be machined
Explanation: Extra metal is provided where material will subsequently be removed.
Q23. Draft allowance is generally provided on:
A. Vertical surfaces
B. Horizontal surfaces only
C. Riser only
D. Runner only
Answer: A. Vertical surfaces
Explanation: Taper is provided on surfaces parallel to the direction of pattern withdrawal.
Q24. The purpose of draft allowance is to:
A. Increase casting weight
B. Facilitate withdrawal of the pattern
C. Increase metal temperature
D. Reduce permeability
Answer: B. Facilitate withdrawal of the pattern
Explanation: Without adequate draft, the pattern can damage the mould cavity during withdrawal.
Q25. Distortion allowance is mainly provided to compensate for:
A. Unequal contraction
B. Gas evolution
C. Sand permeability
D. Metal colour
Answer: A. Unequal contraction
Explanation: Different portions of a casting may cool and contract at different rates, causing distortion.
Q26. Shake allowance is generally associated with:
A. Rapping of the pattern
B. Metal melting
C. Core baking
D. Welding
Answer: A. Rapping of the pattern
Explanation: Rapping can enlarge the mould cavity slightly, so an allowance may be used to compensate.
Q27. Which of the following is NOT a common pattern allowance?
A. Shrinkage
B. Draft
C. Machining
D. Electrical resistance
Answer: D. Electrical resistance
Explanation: Electrical resistance is not a pattern allowance.
Q28. Pattern dimensions are generally larger than final casting dimensions mainly because of:
A. Shrinkage
B. Permeability
C. Refractoriness
D. Cohesiveness
Answer: A. Shrinkage
Explanation: Metal contracts during solidification and cooling.
Q29. A pattern should generally be designed so that it can be:
A. Easily withdrawn from the mould
B. Permanently locked inside the mould
C. Melted with the metal in every process
D. Used as a cutting tool
Answer: A. Easily withdrawn from the mould
Explanation: Proper pattern design and draft are essential for producing an undamaged mould cavity.
Q30. Which pattern is commonly mounted on a plate?
A. Match-plate pattern
B. Sweep pattern
C. Skeleton pattern
D. Single-piece pattern
Answer: A. Match-plate pattern
Explanation: Pattern halves and often the gating system are mounted on opposite sides of a match plate.
MCQ 31–50 — Moulding Sand & Cores
Q31. The most important property of moulding sand for escape of gases is:
A. Permeability
B. Hardness
C. Density
D. Thermal conductivity
Answer: A. Permeability
Explanation: Permeability allows gases to pass through the mould.
Q32. High refractoriness is particularly important because:
A. Sand must withstand molten-metal temperature
B. Sand must conduct electricity
C. Sand must become magnetic
D. Sand must melt quickly
Answer: A. Sand must withstand molten-metal temperature
Explanation: Moulding sand should not melt or deteriorate excessively when exposed to molten metal.
Q33. The ability of sand grains to hold together is:
A. Cohesiveness
B. Permeability
C. Refractoriness
D. Fluidity
Answer: A. Cohesiveness
Explanation: Cohesiveness is the bonding tendency between sand grains.
Q34. The ability of moulding sand to stick to the moulding box is:
A. Adhesiveness
B. Refractoriness
C. Permeability
D. Collapsibility
Answer: A. Adhesiveness
Explanation: Adhesiveness allows the sand to adhere to the moulding-box surface.
Q35. The ability of moulding sand to reproduce the pattern shape is related to:
A. Plasticity
B. Density only
C. Electrical conductivity
D. Magnetism
Answer: A. Plasticity
Explanation: Plasticity helps the sand deform around the pattern and retain the required mould shape.
Q36. Good collapsibility of moulding sand helps to:
A. Facilitate casting removal
B. Increase melting point
C. Prevent all gas escape
D. Increase pattern size
Answer: A. Facilitate casting removal
Explanation: After solidification, mould material should yield or break down sufficiently to allow casting contraction and removal.
Q37. Green sand moulding means that the mould is generally:
A. Used in a moist condition
B. Painted green
C. Made only from green-coloured sand
D. Completely molten
Answer: A. Used in a moist condition
Explanation: “Green” refers to the presence of moisture and the mould being used without complete drying.
Q38. Which of the following is NOT an essential property of good moulding sand?
A. Permeability
B. Refractoriness
C. Strength
D. Electrical insulation only
Answer: D. Electrical insulation only
Explanation: Electrical insulation is not a primary moulding-sand requirement.
Q39. A core is generally made from:
A. Core sand
B. Pure molten metal
C. Cutting fluid
D. Lubricating oil
Answer: A. Core sand
Explanation: Cores are commonly produced from specially prepared sand mixtures designed to withstand casting conditions and provide suitable collapsibility.
Q40. A core is used to produce:
A. Internal cavities
B. External draft
C. Surface colour
D. Metal hardness
Answer: A. Internal cavities
Explanation: The core occupies the space that must remain hollow in the finished casting.
Q41. Core prints are provided to:
A. Support and locate cores
B. Increase metal temperature
C. Measure hardness
D. Remove slag
Answer: A. Support and locate cores
Explanation: Core prints create supporting seats for positioning the core accurately.
Q42. Excessively low permeability may cause:
A. Gas-related defects
B. Better venting
C. Higher ductility
D. Lower melting temperature
Answer: A. Gas-related defects
Explanation: If gases cannot escape adequately, defects such as blowholes may develop.
Q43. Excessively high moisture in moulding sand may contribute to:
A. Gas defects
B. Increased tensile strength
C. Improved electrical conductivity
D. Higher metal hardness
Answer: A. Gas defects
Explanation: Moisture can generate steam and gases when molten metal enters the mould.
Q44. Which property helps moulding sand withstand molten metal without fusing?
A. Refractoriness
B. Adhesiveness
C. Plasticity
D. Permeability
Answer: A. Refractoriness
Explanation: Refractoriness is resistance to high temperatures.
Q45. Which property is especially important for releasing gases from a mould?
A. Permeability
B. Cohesiveness
C. Adhesiveness
D. Hardness
Answer: A. Permeability
Explanation: Gas escape through the mould is essential to prevent gas-related defects.
Q46. A moulding sand with inadequate strength may:
A. Break or erode during pouring
B. Always improve casting quality
C. Increase metal strength
D. Prevent all defects
Answer: A. Break or erode during pouring
Explanation: Insufficient mould strength can cause mould damage, sand inclusion and dimensional problems.
Q47. Which property is particularly important for easy removal of the casting?
A. Collapsibility
B. Electrical conductivity
C. Magnetism
D. Hardness only
Answer: A. Collapsibility
Explanation: A collapsible mould breaks down sufficiently to release the casting.
Q48. A core should generally have sufficient:
A. Strength and refractoriness
B. Electrical resistance only
C. Transparency
D. Magnetism only
Answer: A. Strength and refractoriness
Explanation: The core must retain its shape and withstand contact with molten metal.
Q49. The primary function of a core is:
A. To make an internal passage
B. To melt the casting
C. To harden the pattern
D. To feed molten metal
Answer: A. To make an internal passage
Explanation: Cores create internal cavities or passages that cannot normally be produced by the mould cavity alone.
Q50. Which of the following is correctly matched?
A. Permeability — gas escape
B. Refractoriness — pattern withdrawal
C. Draft — gas escape
D. Core print — melting
Answer: A. Permeability — gas escape
Explanation: Permeability permits gases to escape through the mould.
MCQ 51–70 — Gating System, Riser & Furnace
Q51. The gating system is used to:
A. Carry molten metal into the mould cavity
B. Remove machining chips
C. Test hardness
D. Measure elongation
Answer: A. Carry molten metal into the mould cavity
Explanation: The gating system provides controlled passages for molten metal from the pouring location to the cavity.
Q52. The vertical passage in a gating system is called:
A. Runner
B. Sprue
C. Ingate
D. Riser
Answer: B. Sprue
Explanation: The sprue carries molten metal downward from the pouring basin.
Q53. The horizontal passage connecting the sprue to the ingate is generally called:
A. Runner
B. Core
C. Riser
D. Chill
Answer: A. Runner
Explanation: The runner distributes molten metal from the sprue to one or more ingates.
Q54. The passage through which molten metal enters the mould cavity is:
A. Ingate
B. Sprue
C. Riser
D. Vent
Answer: A. Ingate
Explanation: The ingate is the final entry passage into the casting cavity.
Q55. The main purpose of a riser is to:
A. Feed molten metal during solidification
B. Increase mould permeability
C. Remove the pattern
D. Reduce metal temperature immediately
Answer: A. Feed molten metal during solidification
Explanation: A riser supplies additional liquid metal to compensate for solidification shrinkage.
Q56. A riser should generally remain molten:
A. Longer than the casting region it feeds
B. For no time
C. Only before pouring
D. Only during mould preparation
Answer: A. Longer than the casting region it feeds
Explanation: The riser must provide liquid metal while the casting is solidifying and contracting.
Q57. Directional solidification is promoted primarily to:
A. Guide solidification toward the riser
B. Prevent metal melting
C. Increase sand moisture
D. Remove the pattern
Answer: A. Guide solidification toward the riser
Explanation: Proper casting design and feeding promote solidification from remote regions toward the riser.
Q58. A chill is used to:
A. Increase local cooling rate
B. Increase pouring temperature
C. Reduce mould strength
D. Remove the core
Answer: A. Increase local cooling rate
Explanation: Chills extract heat rapidly from selected regions.
Q59. A pouring basin is located:
A. At the top of the gating system
B. Inside the riser only
C. Under the casting
D. Inside the core
Answer: A. At the top of the gating system
Explanation: The pouring basin receives metal from the ladle and directs it into the sprue.

Q60. The main function of a runner is to:
A. Distribute molten metal
B. Measure hardness
C. Support the core
D. Remove moisture
Answer: A. Distribute molten metal
Explanation: The runner carries metal from the sprue toward the ingates.
Q61. The cupola furnace is mainly used for melting:
A. Cast iron
B. Aluminium foil only
C. Copper wire only
D. Plastic
Answer: A. Cast iron
Explanation: Cupola furnaces are traditionally used in foundries for melting cast iron.
Q62. The usual fuel in a conventional cupola furnace is:
A. Coke
B. Wood only
C. Petrol
D. Natural rubber
Answer: A. Coke
Explanation: Coke serves as the primary fuel and also contributes to the metallurgical environment in the cupola.
Q63. Air is supplied to a cupola through:
A. Tuyeres
B. Risers
C. Runners
D. Cores
Answer: A. Tuyeres
Explanation: Tuyeres introduce air into the furnace to support combustion.
Q64. The cupola is essentially a:
A. Vertical cylindrical furnace
B. Horizontal milling machine
C. Lathe
D. Hydraulic press
Answer: A. Vertical cylindrical furnace
Explanation: A cupola is a vertical shaft-type furnace used for melting cast iron.
Q65. Slag is removed from a cupola through the:
A. Slag hole
B. Core print
C. Runner
D. Ingate
Answer: A. Slag hole
Explanation: A separate slag opening allows accumulated slag to be removed.
Q66. Molten metal is generally tapped from a cupola through the:
A. Tap hole
B. Vent
C. Core print
D. Riser
Answer: A. Tap hole
Explanation: The tap hole is used to withdraw molten metal from the furnace.

Q67. The function of the wind belt in a cupola is associated with:
A. Distribution of air to tuyeres
B. Removing patterns
C. Machining castings
D. Measuring temperature only
Answer: A. Distribution of air to tuyeres
Explanation: The wind belt/plenum distributes the supplied air to the tuyere openings.
Q68. Which furnace is traditionally associated with cast-iron melting in foundries?
A. Cupola
B. Blast furnace only
C. Electric kettle
D. Reverberatory laboratory oven only
Answer: A. Cupola
Explanation: The cupola has long been a common foundry furnace for cast iron.
Q69. Proper gating design primarily helps control:
A. Flow of molten metal
B. Electrical resistance
C. Tool hardness
D. Pattern colour
Answer: A. Flow of molten metal
Explanation: Gating determines how metal enters and fills the cavity and helps manage turbulence and inclusions.
Q70. A properly designed riser helps reduce:
A. Shrinkage defects
B. Tool wear
C. Electrical resistance
D. Pattern moisture
Answer: A. Shrinkage defects
Explanation: The riser feeds liquid metal to compensate for solidification contraction.
MCQ 71–90 — Casting Defects
Q71. A cavity caused by trapped gas in a casting is called:
A. Blowhole
B. Misrun
C. Cold shut
D. Hot tear
Answer: A. Blowhole
Explanation: Blowholes are gas cavities resulting from inadequate escape of gases.
Q72. A casting that fails to completely fill the mould cavity has:
A. Misrun
B. Blowhole
C. Scab
D. Penetration
Answer: A. Misrun
Explanation: Misrun occurs when molten metal solidifies before the cavity is completely filled.
Q73. A defect caused by improper fusion of two streams of molten metal is:
A. Cold shut
B. Blowhole
C. Shrinkage cavity
D. Sand inclusion
Answer: A. Cold shut
Explanation: A cold shut appears where two streams meet but do not properly fuse.

Q74. A shrinkage cavity is mainly associated with:
A. Inadequate feeding during solidification
B. Excessive pattern draft
C. High permeability alone
D. Good directional solidification
Answer: A. Inadequate feeding during solidification
Explanation: If liquid metal is not available to compensate for contraction, shrinkage cavities can form.
Q75. Which defect is associated with cracking during the late stage of solidification?
A. Hot tear
B. Blowhole
C. Misrun
D. Sand inclusion
Answer: A. Hot tear
Explanation: Hot tearing occurs when contraction is restrained while the metal has insufficient strength to accommodate the resulting stresses.
Q76. Excess moisture in moulding sand may contribute to:
A. Blowholes
B. Increased hardness
C. Better machining
D. Higher ductility
Answer: A. Blowholes
Explanation: Moisture can generate steam and other gases during pouring.
Q77. A defect resulting from sand particles becoming embedded in the casting is:
A. Sand inclusion
B. Cold shut
C. Misrun
D. Hot tear
Answer: A. Sand inclusion
Explanation: Erosion or breakdown of the mould can cause sand to enter the molten metal.
Q78. Metal penetrating into spaces between sand grains can produce:
A. Metal penetration
B. Misrun
C. Blowhole
D. Hot tear
Answer: A. Metal penetration
Explanation: Molten metal can enter the mould’s surface pores under certain conditions, producing a rough casting surface.
Q79. Which defect is most directly related to incomplete filling?
A. Misrun
B. Blowhole
C. Shrinkage cavity
D. Sand inclusion
Answer: A. Misrun
Explanation: Misrun means the mould cavity is not completely filled.
Q80. Which defect appears as a seam where two metal fronts meet?
A. Cold shut
B. Blowhole
C. Shrinkage
D. Scab
Answer: A. Cold shut
Explanation: Two metal streams that meet without proper fusion create a cold-shut indication.

Q81. Proper riser design mainly prevents:
A. Shrinkage cavity
B. Tool chatter
C. Electrical short circuit
D. Pattern wear
Answer: A. Shrinkage cavity
Explanation: Risers provide molten metal to compensate for solidification contraction.
Q82. Poor mould permeability is most likely to cause:
A. Gas-related defects
B. Increased ductility
C. Better surface finish always
D. Higher melting point
Answer: A. Gas-related defects
Explanation: Trapped gases can produce blowholes and other gas-related imperfections.
Q83. Excessive turbulence in the gating system may promote:
A. Mould erosion and inclusions
B. Perfect casting quality
C. Higher hardness only
D. Lower density of the mould
Answer: A. Mould erosion and inclusions
Explanation: Turbulent flow can erode mould surfaces and entrain oxides or sand.
Q84. A hot tear is associated with:
A. Restrained contraction
B. Excessive permeability only
C. Pattern colour
D. Low hardness of the pattern only
Answer: A. Restrained contraction
Explanation: During solidification, contraction can generate stresses that cause tearing when movement is restrained.
Q85. Which defect is caused primarily by insufficient molten metal feeding?
A. Shrinkage cavity
B. Cold shut
C. Sand inclusion
D. Scab
Answer: A. Shrinkage cavity
Explanation: Inadequate feeding leaves a void as the metal contracts during solidification.
Q86. A casting defect caused by two streams meeting without complete fusion is:
A. Cold shut
B. Blowhole
C. Metal penetration
D. Shrinkage cavity
Answer: A. Cold shut
Explanation: The streams meet at a temperature or condition insufficient for proper fusion.
Q87. Which defect is most likely associated with inadequate venting?
A. Blowhole
B. Hot tear
C. Misrun only
D. Mismatch only
Answer: A. Blowhole
Explanation: Inadequate venting can trap gases inside the mould and produce blowholes.
Q88. An irregular crack caused during solidification is most closely associated with:
A. Hot tear
B. Misrun
C. Sand inclusion
D. Blowhole
Answer: A. Hot tear
Explanation: Hot tears are cracks that develop during the final stages of solidification under restrained contraction.
Q89. Which casting defect is associated with erosion of mould material?
A. Sand inclusion
B. UTS
C. Yielding
D. Creep
Answer: A. Sand inclusion
Explanation: Mould erosion can release sand particles that become entrapped in the casting.
Q90. Which measure can help reduce shrinkage defects?
A. Proper riser design
B. Removing all risers
C. Increasing mould damage
D. Eliminating feeding
Answer: A. Proper riser design
Explanation: Properly located and sized risers provide liquid metal during solidification.

MCQ 91–100 — Special Casting Processes
Q91. Investment casting is also known as:
A. Lost-wax casting
B. Sand forging
C. Pressure welding
D. Cold rolling
Answer: A. Lost-wax casting
Explanation: A wax pattern is used and subsequently removed from the refractory mould before metal pouring.
Q92. Investment casting is particularly suitable for:
A. Complex and detailed shapes
B. Only simple flat plates
C. Only rolled sheets
D. Only welded joints
Answer: A. Complex and detailed shapes
Explanation: The process can reproduce intricate geometries with good dimensional accuracy and surface finish.
Q93. In die casting, molten metal is introduced into the die:
A. Under pressure
B. Only by gravity in all cases
C. By hammering
D. By rolling
Answer: A. Under pressure
Explanation: Pressure die casting forces molten metal into a reusable metallic die.
Q94. Die casting is particularly suitable for:
A. High-volume production
B. One-off wooden patterns only
C. Very large sand moulds only
D. Hand forging
Answer: A. High-volume production
Explanation: Reusable dies and rapid cycles make die casting suitable for high production rates.
Q95. Which material is commonly used in pressure die casting?
A. Aluminium alloy
B. Concrete
C. Wood
D. Rubber only
Answer: A. Aluminium alloy
Explanation: Aluminium, zinc and magnesium alloys are common die-casting materials.
Q96. Centrifugal casting uses:
A. A rotating mould
B. A fixed wooden pattern only
C. A hammer
D. A rolling mill
Answer: A. A rotating mould
Explanation: Rotation generates centrifugal force that distributes molten metal against the mould wall.
Q97. Centrifugal casting is particularly suitable for producing:
A. Pipes and cylindrical components
B. Flat sheets only
C. Bolts by forging only
D. Wooden components
Answer: A. Pipes and cylindrical components
Explanation: The process is especially effective for tubular and rotationally symmetric castings.
Q98. Shell moulding uses:
A. Resin-bonded sand shell
B. Pure water only
C. Forged steel mould only
D. Wax without refractory material
Answer: A. Resin-bonded sand shell
Explanation: A thin shell of resin-bonded sand is formed around a heated pattern.
Q99. Continuous casting produces:
A. A continuously withdrawn solidifying strand
B. Only individual sand castings
C. Forged gears only
D. Welded pipes only
Answer: A. A continuously withdrawn solidifying strand
Explanation: Molten metal is continuously supplied to a mould while the partially solidified product is continuously withdrawn.
Q100. Which casting process is most closely associated with a rotating mould?
A. Centrifugal casting
B. Investment casting
C. Sand casting
D. Shell moulding
Answer: A. Centrifugal casting
Explanation: Rotation of the mould is the defining feature of centrifugal casting.

CHAPTER 5 — ONE-PAGE REVISION
Pattern
Pattern → Mould cavity
Pattern Allowances
Shrinkage → Cooling contraction
Machining → Future machining
Draft → Easy withdrawal
Distortion → Unequal contraction
Shake → Rapping effect
Moulding Sand
Permeability → Gas escape
Refractoriness → High-temperature resistance
Cohesiveness → Sand grains stick together
Adhesiveness → Sand sticks to mould box
Plasticity → Reproduces pattern shape
Collapsibility → Easy casting removal
Gating
Pouring Basin → Receives molten metal
Sprue → Vertical passage
Runner → Distributes metal
Ingate → Entry into cavity
Riser → Feeds molten metal
Chill → Faster local cooling
Defects
Blowhole → Gas
Misrun → Incomplete filling
Cold Shut → Incomplete fusion
Shrinkage Cavity → Poor feeding
Hot Tear → Restrained contraction
Sand Inclusion → Mould sand enters casting
Metal Penetration → Metal enters sand pores
Special Processes
Investment → Lost wax
Die Casting → Pressure + permanent die
Centrifugal → Rotating mould
Shell Moulding → Resin-coated sand shell
Continuous Casting → Continuous strand
CHAPTER 6 — METAL FORMING PROCESSES

6.1 Introduction
Metal forming is a manufacturing process in which a metal workpiece is plastically deformed into the required shape by applying an external force.
Unlike machining, metal forming generally does not remove material in the form of chips.
Metal forming is widely used in:
Automobile components
Railway components
Aircraft structures
Machine parts
Pipes and tubes
Sheets and plates
Shafts
Gears
Connecting rods
Bolts and fasteners
6.2 Definition of Metal Forming
Metal forming is a manufacturing process in which the shape of a metal is changed permanently by plastic deformation under the action of externally applied forces.
Key Point
Metal forming → Plastic deformation → Required shape
6.3 Principle of Metal Forming
The basic principle is based on the plasticity of metals.
When a sufficiently large force is applied to a metal:
Elastic deformation occurs initially.
The applied stress reaches the yield strength.
Plastic deformation begins.
After removal of the load, the material retains its newly formed shape.
Therefore:
Elastic deformation → Yielding → Plastic deformation → Permanent shape

6.4 Classification of Metal Forming
Metal forming processes can broadly be classified into:
A. Bulk Deformation Processes
These involve relatively large changes in cross-section.
Important processes:
Rolling
Forging
Extrusion
Drawing
B. Sheet Metal Forming Processes
These are generally performed on sheet or strip materials.
Important processes:
Bending
Deep drawing
Blanking
Punching
Bending
Shearing
Embossing
Coining
6.5 Hot Working
Hot working is metal deformation carried out at a temperature sufficiently high that significant recrystallization occurs during deformation.
Examples:
Hot rolling
Hot forging
Hot extrusion
Advantages
Lower forming force
Large deformation possible
Improved workability
Grain refinement can occur
Internal defects may be reduced or closed under suitable conditions
Disadvantages
Oxidation/scaling
Poorer surface finish
Less dimensional accuracy than many cold-working operations
Heating equipment required
6.6 Cold Working
Cold working is plastic deformation performed below the recrystallization temperature, commonly near room temperature.
Examples:
Cold rolling
Wire drawing
Cold extrusion
Cold forging
Advantages
Better surface finish
Better dimensional accuracy
Increased strength and hardness due to strain hardening
No heating scale from hot working
Disadvantages
Higher forming force
Lower ductility
Residual stresses may develop
Greater tool wear can occur
6.7 Warm Working
Warm working is carried out at a temperature between typical cold-working and hot-working conditions.
It can provide a compromise between:
Lower forming force than cold working
Better surface and dimensional control than many hot-working operations
6.8 Recrystallization
Recrystallization is the formation of new, relatively strain-free grains in a plastically deformed metal during appropriate heat treatment.
The recrystallization temperature is important in distinguishing hot and cold working.
Remember
Above suitable recrystallization conditions → Hot working
Below recrystallization temperature → Cold working
6.9 Strain Hardening
Strain hardening, also called work hardening, is the increase in strength and hardness of a metal due to plastic deformation.
It is particularly important in cold working.
Effect of Cold Working
Generally:
Strength ↑
Hardness ↑
Ductility ↓
6.10 Rolling
Rolling is a metal-forming process in which metal is passed between rotating rolls to reduce thickness or change its cross-sectional shape.
Basic principle
Metal → Rotating rolls → Plastic deformation → Reduced thickness/changed shape
6.11 Products of Rolling
Rolling can produce:
Sheets
Plates
Strips
Bars
Rails
Structural sections
Rods
6.12 Types of Rolling Mills
Important rolling-mill arrangements include:
Two-high rolling mill
Three-high rolling mill
Four-high rolling mill
Cluster rolling mill
Tandem rolling mill
6.13 Two-High Rolling Mill
A two-high rolling mill has:
Two rolls
The rolls may rotate in opposite directions at the point of contact with the workpiece.
6.14 Three-High Rolling Mill
A three-high mill consists of:
Three rolls arranged vertically.
The workpiece can pass alternately between the upper and middle rolls and between the middle and lower rolls.
6.15 Four-High Rolling Mill
A four-high rolling mill consists of:
Two small work rolls
Two larger backup rolls
Main purpose of backup rolls
They support the smaller work rolls and reduce bending.
6.16 Cluster Rolling Mill
A cluster mill uses multiple backup rolls to support relatively small work rolls.
It is useful for rolling thin material.
6.17 Tandem Rolling Mill
A tandem rolling mill contains several rolling stands arranged in succession.
The strip passes continuously through multiple stands.
Advantage
High production rate.
6.18 Roll Bite
The roll bite is the region where the workpiece is in contact with the rolls.
For rolling to occur, friction between the rolls and workpiece must be sufficient to draw the material into the roll gap.
6.19 Neutral Point
The neutral point is the point along the arc of contact where the velocity of the strip equals the peripheral velocity of the roll.
6.20 Forward Slip
In rolling, the exit velocity of the strip is generally greater than the peripheral velocity of the roll.
This difference is associated with forward slip.
6.21 Forging
Forging is a metal-forming process in which a workpiece is plastically deformed under compressive forces.
Forces may be applied using:
Hammer
Press
Die
Forging is widely used for producing:
Crankshafts
Connecting rods
Spanners
Axles
Shafts
Bolts
Aircraft components
6.22 Advantages of Forging
Important advantages include:
High strength
Good toughness
Improved grain flow
Reduced internal defects under suitable processing
Excellent mechanical properties for many applications
6.23 Open-Die Forging
In open-die forging, the workpiece is compressed between dies that do not completely enclose it.
It is commonly used for:
Large components
Low-to-medium production
Large shafts
Heavy forgings
6.24 Closed-Die Forging
In closed-die forging, the workpiece is deformed within impressions in the dies.
It is suitable for:
Complex shapes
High production
Better dimensional consistency
Excess material may form flash at the die parting line.
6.25 Flash
Flash is excess metal squeezed out between the die halves during closed-die forging.
The flash is generally removed after forging.
6.26 Drop Forging
Drop forging uses repeated blows from a hammer to deform the workpiece in dies.
The energy of the falling hammer produces the deformation.
6.27 Press Forging
In press forging, deformation is produced primarily by continuous squeezing pressure rather than repeated impact blows.
Comparison
Hammer forging → Impact
Press forging → Continuous pressure
6.28 Extrusion
Extrusion is a metal-forming process in which a billet is forced through a die opening to produce a long product of constant cross-section.
Examples:
Rods
Tubes
Channels
Aluminium sections
Window frames
6.29 Direct Extrusion
In direct extrusion, the billet and ram move in the same direction relative to the die opening.
The ram pushes the billet through the die.
6.30 Indirect Extrusion
In indirect extrusion, the die moves toward or into the billet, and the extruded material flows opposite to the direction of ram movement.
Important
Direct extrusion → Billet flow generally same direction as ram movement
Indirect extrusion → Metal flow opposite to ram movement
6.31 Extrusion Ratio
The extrusion ratio is generally defined as:
Where:
= initial cross-sectional area
= final extruded cross-sectional area
A larger extrusion ratio indicates a greater reduction in cross-sectional area.
6.32 Drawing
Drawing is a metal-forming process in which a wire, rod or tube is pulled through a die to reduce its cross-sectional area and/or change its shape.
Important
Extrusion → Material is pushed through die
Drawing → Material is pulled through die
6.33 Wire Drawing
Wire drawing is commonly used to produce:
Electrical wires
Fine wires
Cables
Springs
Small-diameter rods
6.34 Tube Drawing
Tube drawing is used to reduce the diameter or wall dimensions of tubes.
A mandrel may be used when control of internal dimensions is required.
6.35 Sheet Metal Working
Sheet metal processes transform thin metal sheets into useful components.
Common operations include:
Shearing
Blanking
Punching
Bending
Deep drawing
Embossing
Coining
6.36 Shearing
Shearing is a cutting operation in which a sheet is separated by applying shear forces.
It is performed using tools such as:
Shears
Punch and die
6.37 Blanking
In blanking, the portion cut out from the sheet is the desired product.
Golden Rule
Blanking → Blank is the product
6.38 Punching
In punching, the hole produced in the sheet is the desired feature, while the removed slug is generally scrap.
Golden Rule
Punching → Hole is the desired feature
6.39 Bending
Bending changes the shape of a sheet or strip by applying force without intentionally removing material.
Examples:
V-bending
U-bending
Angle bending
6.40 Springback
Springback is the elastic recovery of a sheet after the bending load is removed.
Because of springback, the final angle may differ from the angle imposed by the tooling.
Reduction of Springback
It can be controlled by:
Over-bending
Coining
Appropriate tooling
Process optimization
6.41 Deep Drawing
Deep drawing is a sheet-metal forming process in which a flat blank is drawn into a die to produce a cup-like or hollow component.
Examples:
Cups
Cans
Kitchen utensils
Automotive components
6.42 Blank Holder
A blank holder is used in deep drawing to control the movement of the sheet and help prevent wrinkling.
6.43 Punch and Die
In sheet-metal operations:
Punch → Moves into/through the sheet
Die → Supports and provides the required opening
The clearance between punch and die is important for cutting quality and tool life.
6.44 Embossing
Embossing produces raised or recessed designs on sheet metal.
It is commonly used for:
Identification marks
Decorative patterns
Stiffening features
6.45 Coining
Coining is a severe sheet-metal forming operation in which the material is subjected to high compressive pressure between dies.
It can produce:
Fine details
Accurate impressions
Raised or recessed features
6.46 Advantages of Metal Forming
Major advantages:
High production rate
Good material utilization
Improved mechanical properties in many processes
Good surface finish in cold working
Reduced machining requirements
Suitable for mass production
6.47 Limitations
Limitations include:
High initial tooling cost
High forming forces
Springback in sheet-metal forming
Work hardening
Residual stresses
Defects such as laps, cracks and wrinkles
6.48 Common Forming Defects
Important defects include:
Cracks
Laps
Wrinkles
Surface defects
Internal defects
Alligatoring
Excessive springback
6.49 Quick Revision Table
Process Main Principle
Rolling Metal passes between rolls
Forging Compressive deformation
Extrusion Pushing metal through die
Drawing Pulling metal through die
Blanking Cut-out piece is product
Punching Hole is desired feature
Bending Change in sheet angle/shape
Deep drawing Sheet converted into cup/hollow form
Embossing Raised/recessed design
Coining High-pressure impression
Hot working Above suitable recrystallization conditions
Cold working Below recrystallization temperature
Warm working Intermediate temperature range
Springback Elastic recovery
Strain hardening Strength increase due to plastic deformation

Q1. Metal forming is primarily based on:

A. Elastic deformation
B. Plastic deformation
C. Brittle fracture
D. Melting
Answer: B. Plastic deformation
Explanation: Metal forming permanently changes the shape of a material through plastic deformation.
Q2. Which of the following is a bulk metal-forming process?
A. Rolling
B. Painting
C. Welding
D. Grinding
Answer: A. Rolling
Explanation: Rolling is one of the major bulk deformation processes.
Q3. Which process uses rotating rolls to reduce the thickness of metal?
A. Forging
B. Rolling
C. Drawing
D. Casting
Answer: B. Rolling
Explanation: Rolling passes the workpiece through the gap between rotating rolls.
Q4. Forging primarily involves:
A. Tensile forces
B. Compressive forces
C. Electrical forces
D. Thermal radiation only
Answer: B. Compressive forces
Explanation: Forging plastically deforms the workpiece mainly through compressive loading.
Q5. In extrusion, the billet is:
A. Pulled through the die
B. Pushed through the die
C. Melted completely
D. Rolled into a sheet
Answer: B. Pushed through the die
Explanation: A ram applies compressive force to force the billet through the die opening.
Q6. In drawing, the workpiece is:
A. Pushed through the die
B. Pulled through the die
C. Melted
D. Cast
Answer: B. Pulled through the die
Explanation: Drawing reduces the cross-section by pulling the material through a die.
Q7. Which process generally increases hardness due to strain hardening?
A. Cold working
B. Annealing
C. Casting only
D. Melting
Answer: A. Cold working
Explanation: Plastic deformation at low temperature increases dislocation density, generally increasing strength and hardness.
Q8. One common disadvantage of cold working is:
A. Increased ductility
B. Work hardening
C. Complete elimination of residual stress
D. Loss of all strength
Answer: B. Work hardening
Explanation: Cold deformation increases strength and hardness but reduces ductility.
Q9. Which process is generally performed at a temperature where recrystallization can occur during deformation?
A. Hot working
B. Cold working
C. Room-temperature machining
D. Grinding
Answer: A. Hot working
Explanation: Hot working occurs at sufficiently elevated temperatures to permit significant recrystallization during deformation.
Q10. Which of the following is a sheet-metal operation?
A. Deep drawing
B. Blast furnace melting
C. Sand moulding
D. Arc welding
Answer: A. Deep drawing
Explanation: Deep drawing forms sheet metal into cup-like or hollow shapes.
Q11. In blanking:
A. The hole is the product
B. The blank is the product
C. Both are always scrap
D. No material is removed
Answer: B. The blank is the product
Explanation: The cut-out portion of the sheet is the desired component in blanking.
Q12. In punching:
A. The hole is the desired feature
B. The slug is always the final product
C. No cutting occurs
D. The sheet is melted
Answer: A. The hole is the desired feature
Explanation: Punching produces a hole in the sheet; the removed slug is generally scrap.
Q13. Springback in sheet metal is caused by:
A. Elastic recovery
B. Melting
C. Plastic flow only
D. Oxidation
Answer: A. Elastic recovery
Explanation: After the forming load is removed, the elastically deformed material partially returns toward its original shape.
Q14. Which operation produces a cup-like component from a flat sheet?
A. Deep drawing
B. Rolling
C. Wire drawing
D. Forging
Answer: A. Deep drawing
Explanation: Deep drawing transforms a flat blank into a hollow component.
Q15. A four-high rolling mill uses:
A. Four work rolls
B. Two work rolls and two backup rolls
C. One work roll and three dies
D. Four dies
Answer: B. Two work rolls and two backup rolls
Explanation: The smaller work rolls are supported by larger backup rolls.
Q16. A tandem rolling mill consists of:
A. Several rolling stands in succession
B. One die only
C. One hammer only
D. A furnace and a mould
Answer: A. Several rolling stands in succession
Explanation: Multiple stands permit successive reductions and high production rates.
Q17. Excess metal squeezed out between closed forging dies is called:
A. Flash
B. Burr only
C. Slag
D. Riser
Answer: A. Flash
Explanation: Flash forms at the die parting line during closed-die forging and is subsequently trimmed.
Q18. Open-die forging is especially suitable for:
A. Large components
B. Only tiny electronic parts
C. Thin plastic films
D. Glass bottles
Answer: A. Large components
Explanation: Open-die forging is commonly used for large shafts, rings and other heavy components.
Q19. The extrusion ratio is generally:
A.
B.
C.
D.
Answer: B.
Explanation:
where is the initial billet area and is the final extruded area.
Q20. In indirect extrusion, metal flow is generally:
A. In the same direction as ram movement
B. Opposite to ram movement
C. Perpendicular to the die
D. Circular only
Answer: B. Opposite to ram movement
Explanation: In indirect extrusion, the die moves into the billet and material flows through the die in the opposite direction to the ram.

Q21. The main purpose of rolling is to:
A. Increase the thickness of a plate
B. Reduce thickness or change cross-section
C. Join two metals
D. Remove chips
Answer: B. Reduce thickness or change cross-section
Explanation: Rolling plastically deforms metal between rotating rolls to reduce thickness or produce a required section.
Q22. In rolling, the workpiece is subjected mainly to:
A. Tensile stress
B. Compressive stress
C. Torsional stress only
D. Bending stress only
Answer: B. Compressive stress
Explanation: The rolls apply compressive forces to reduce the thickness of the workpiece.
Q23. Which product can commonly be manufactured by rolling?
A. Sheet
B. Sand mould
C. Welding electrode only
D. Cutting fluid
Answer: A. Sheet
Explanation: Sheets, plates, strips, rails and structural sections are common rolling products.
Q24. The distance between the surfaces of two rolls at the point of minimum separation is called:
A. Roll gap
B. Draft angle
C. Die clearance
D. Pitch
Answer: A. Roll gap
Explanation: Roll gap is the minimum separation between the two rolls through which the material passes.
Q25. Draft in rolling refers to:
A. Increase in thickness
B. Reduction in thickness
C. Increase in width only
D. Reduction in length only
Answer: B. Reduction in thickness
Explanation:
where is the initial thickness and is the final thickness.
Q26. If the initial thickness is 20 mm and final thickness is 15 mm, the draft is:
A. 3 mm
B. 5 mm
C. 15 mm
D. 35 mm
Answer: B. 5 mm
Explanation:

Q27. The percentage reduction in thickness is calculated by:
A.
B.
C.
D.
Answer: B.
Explanation: Percentage reduction represents the decrease in thickness relative to the initial thickness.
Q28. The roll bite is the region where:
A. Metal is heated
B. Metal contacts the rolls
C. Metal is melted
D. Metal is welded
Answer: B. Metal contacts the rolls
Explanation: The arc or region of contact between the workpiece and rolls is associated with the roll bite.
Q29. Friction between the rolls and workpiece is necessary primarily to:
A. Prevent deformation
B. Draw the workpiece into the rolls
C. Melt the workpiece
D. Increase electrical resistance
Answer: B. Draw the workpiece into the rolls
Explanation: Adequate friction enables the rolls to grip and pull the workpiece into the roll gap.
Q30. Excessive friction in rolling can lead to:
A. Reduced roll wear
B. Increased power requirement and defects
C. Zero deformation
D. Elimination of all stresses
Answer: B. Increased power requirement and defects
Explanation: Although friction is required for biting, excessive friction increases power consumption and may promote undesirable deformation.

Q31. A two-high rolling mill consists of:
A. Two rolls
B. Three rolls
C. Four rolls
D. Six rolls
Answer: A. Two rolls
Explanation: The simplest rolling mill arrangement has two rolls.
Q32. In a three-high rolling mill, the rolls are generally arranged:
A. Horizontally in one plane
B. Vertically one above another
C. In a triangular pattern
D. Randomly
Answer: B. Vertically one above another
Explanation: Three-high mills use three rolls positioned one above another.
Q33. The major advantage of a three-high rolling mill is:
A. Reversal of workpiece movement without reversing roll rotation
B. No need for friction
C. No deformation
D. Elimination of all roll wear
Answer: A. Reversal of workpiece movement without reversing roll rotation
Explanation: The workpiece can pass alternately through the upper and lower roll gaps while the rolls continue rotating in their respective directions.
Q34. In a four-high rolling mill, backup rolls are used mainly to:
A. Heat the metal
B. Support work rolls
C. Cut the metal
D. Lubricate the workpiece
Answer: B. Support work rolls
Explanation: Backup rolls reduce bending of the smaller work rolls.
Q35. A cluster rolling mill is particularly suitable for:
A. Very thin sheets
B. Sand casting
C. Forging dies only
D. Welding rods only
Answer: A. Very thin sheets
Explanation: Multiple backup rolls permit the use of small work rolls and help produce thin material.
Q36. A tandem rolling mill is used mainly for:
A. Low-speed single-piece production
B. High production rate
C. Hand forging
D. Sand mould preparation
Answer: B. High production rate
Explanation: Multiple stands arranged sequentially permit continuous high-speed rolling.
Q37. In rolling, the neutral point is where:
A. Metal melts
B. Strip velocity equals roll surface velocity
C. Thickness becomes zero
D. Friction becomes zero
Answer: B. Strip velocity equals roll surface velocity
Explanation: The neutral point separates regions of backward and forward slip.
Q38. Forward slip occurs because:
A. Exit strip velocity is greater than roll peripheral velocity
B. Exit strip velocity is zero
C. Roll velocity is always greater than strip velocity
D. The strip melts
Answer: A. Exit strip velocity is greater than roll peripheral velocity
Explanation: The strip accelerates as it moves through the roll bite, resulting in forward slip at exit.
Q39. Roll flattening is caused mainly by:
A. High rolling force
B. Low temperature of air
C. Pattern draft
D. Core expansion
Answer: A. High rolling force
Explanation: Large rolling forces elastically deform the rolls, affecting the effective roll gap.
Q40. Which defect is associated with excessive non-uniform deformation during rolling?
A. Wavy edges
B. Blowhole
C. Cold shut
D. Hot tear
Answer: A. Wavy edges
Explanation: Unequal elongation across the strip width can produce wavy edges.

MCQ 41–60: Forging
Q41. Forging is primarily a:
A. Casting process
B. Metal-forming process
C. Machining process
D. Welding process
Answer: B. Metal-forming process
Explanation: Forging changes the shape of a workpiece through plastic deformation under compressive loading.
Q42. The major force in forging is:
A. Compression
B. Tension
C. Pure torsion
D. Electrical force
Answer: A. Compression
Explanation: Forging dies apply compressive forces to deform the workpiece.
Q43. Open-die forging is generally preferred for:
A. Very large components
B. Tiny electronic components
C. Plastic sheets
D. Glass products
Answer: A. Very large components
Explanation: Open dies can accommodate large workpieces and are widely used for heavy forgings.
Q44. Closed-die forging is particularly suitable for:
A. Complex shapes and high production
B. Only rough large blocks
C. Sand moulds
D. Thin wires only
Answer: A. Complex shapes and high production
Explanation: Die impressions provide controlled shaping and repeatability.
Q45. Flash in closed-die forging is:
A. Molten slag
B. Excess metal squeezed out at the die parting line
C. Lubricant
D. A crack in the forging
Answer: B. Excess metal squeezed out at the die parting line
Explanation: Excess material flows into the flash region between the die halves.
Q46. Flash is generally removed by:
A. Trimming
B. Rolling
C. Casting
D. Annealing only
Answer: A. Trimming
Explanation: A trimming operation removes unwanted flash from the forged component.
Q47. Drop forging uses:
A. Repeated hammer blows
B. Continuous rolling
C. Wire drawing
D. A rotating mould
Answer: A. Repeated hammer blows
Explanation: A hammer delivers impact energy to deform the workpiece within the dies.
Q48. Press forging differs from drop forging because press forging uses mainly:
A. Continuous squeezing action
B. No force
C. Melting
D. Tensile fracture
Answer: A. Continuous squeezing action
Explanation: A forging press applies force progressively rather than mainly through repeated impact blows.
Q49. Which is a major advantage of forged components?
A. Improved grain flow
B. Guaranteed zero machining
C. No tooling required
D. Very low strength
Answer: A. Improved grain flow
Explanation: Proper forging can produce favorable grain flow and excellent mechanical properties.
Q50. Forging is widely used for manufacturing:
A. Connecting rods
B. Glass bottles
C. Sand moulds
D. Plastic films
Answer: A. Connecting rods
Explanation: Connecting rods are commonly produced by forging because of the required strength and toughness.

Q51. A forging defect in which the material folds over itself is called:
A. Lap
B. Blowhole
C. Misrun
D. Porosity
Answer: A. Lap
Explanation: A lap is a surface defect caused by folding of metal during deformation.
Q52. Proper die design is important mainly to:
A. Ensure controlled metal flow
B. Eliminate all friction
C. Melt the workpiece
D. Produce sand
Answer: A. Ensure controlled metal flow
Explanation: Proper die geometry helps material flow correctly and reduces forging defects.
Q53. In impression-die forging, the workpiece is deformed:
A. Within die impressions
B. Between rolling rolls
C. Through a wire-drawing die
D. Inside a sand mould
Answer: A. Within die impressions
Explanation: Die cavities define the desired forging geometry.
Q54. The grain flow produced by forging can improve:
A. Mechanical performance
B. Electrical insulation only
C. Casting permeability
D. Melting temperature only
Answer: A. Mechanical performance
Explanation: Favorable grain flow can improve fatigue strength, toughness and directional mechanical properties.
Q55. Hot forging generally requires:
A. Lower deformation force than cold forging
B. No deformation force
C. Only tensile force
D. No dies
Answer: A. Lower deformation force than cold forging
Explanation: Elevated temperature lowers the flow stress of the material.
Q56. Cold forging generally provides:
A. Good dimensional accuracy and surface finish
B. Heavy oxidation scale
C. Very low strength
D. No work hardening
Answer: A. Good dimensional accuracy and surface finish
Explanation: Cold forging can produce accurate parts and also increases strength through work hardening.
Q57. Which process is commonly used to manufacture bolts in large quantities?
A. Cold heading/cold forging
B. Sand casting only
C. Centrifugal casting
D. Investment casting only
Answer: A. Cold heading/cold forging
Explanation: Cold heading is widely used for high-volume production of fasteners.

Q58. Upsetting in forging generally:
A. Increases cross-sectional area and reduces length
B. Reduces diameter and increases length
C. Produces a hole
D. Cuts the material
Answer: A. Increases cross-sectional area and reduces length
Explanation: In upsetting, the workpiece is compressed along its length.
Q59. Drawing out in forging generally:
A. Increases length and reduces cross-section
B. Decreases length
C. Produces a hole
D. Produces sheet by rolling
Answer: A. Increases length and reduces cross-section
Explanation: Drawing out elongates the workpiece while reducing its cross-sectional dimensions.
Q60. A forging hammer applies:
A. Impact load
B. Pure hydrostatic pressure only
C. Tensile load only
D. Electrical current
Answer: A. Impact load
Explanation: Hammers deform the workpiece using high-energy impact blows.
MCQ 61–80: Extrusion & Drawing
Q61. Extrusion produces:
A. Long products of constant cross-section
B. Only spherical products
C. Only flat sheets
D. Sand moulds
Answer: A. Long products of constant cross-section
Explanation: Material is forced through a die to obtain the required continuous cross-sectional shape.
Q62. In direct extrusion, metal flow is generally:
A. In the direction of ram movement
B. Opposite to ram movement
C. Perpendicular to ram movement
D. Circular
Answer: A. In the direction of ram movement
Explanation: The ram pushes the billet toward and through the die.
Q63. The major advantage of indirect extrusion is:
A. Lower friction between billet and container
B. No deformation
C. No die required
D. No pressure required
Answer: A. Lower friction between billet and container
Explanation: In indirect extrusion, there is less relative movement between the billet and container wall.
Q64. Extrusion is especially suitable for producing:
A. Complex cross-sections
B. Only cast iron blocks
C. Sand cores
D. Weld beads
Answer: A. Complex cross-sections
Explanation: Extrusion can produce intricate and constant cross-sectional profiles.

Q65. Aluminium is widely extruded because of its:
A. Good extrudability
B. Extremely high brittleness
C. Very low plasticity
D. Inability to deform
Answer: A. Good extrudability
Explanation: Aluminium alloys are widely used for extruded sections because many grades have good workability.
Q66. In extrusion, the die determines:
A. Final cross-sectional shape
B. Furnace fuel
C. Metal colour
D. Workpiece temperature only
Answer: A. Final cross-sectional shape
Explanation: The opening in the extrusion die defines the cross-sectional profile of the product.
Q67. The extrusion ratio is the ratio of:
A. Final area to initial area
B. Initial area to final area
C. Initial length to final length
D. Final length to initial length
Answer: B. Initial area to final area
Explanation:
Q68. In wire drawing, the material is:
A. Pulled through a die
B. Pushed through a die
C. Cast into a mould
D. Rolled between four rolls
Answer: A. Pulled through a die
Explanation: Tensile force pulls the wire through the die, reducing its cross-section.
Q69. Wire drawing is commonly used to manufacture:
A. Fine wires
B. Large castings
C. Engine blocks
D. Sand moulds
Answer: A. Fine wires
Explanation: Drawing is an important process for reducing wire diameter.
Q70. The material property most important for successful wire drawing is:
A. Ductility
B. Brittleness
C. Porosity
D. Very low strength
Answer: A. Ductility
Explanation: The material must withstand substantial plastic deformation without cracking.
Q71. A drawing die is used to:
A. Reduce cross-sectional area
B. Increase melting temperature
C. Produce a mould cavity
D. Join two wires
Answer: A. Reduce cross-sectional area
Explanation: The die opening is smaller than the incoming material cross-section.
Q72. Lubrication in drawing is used mainly to:
A. Reduce friction and die wear
B. Increase friction
C. Melt the material
D. Increase oxidation
Answer: A. Reduce friction and die wear
Explanation: Proper lubrication lowers frictional resistance and improves tool life and surface quality.
Q73. Tube drawing may use a mandrel to control:
A. Internal dimensions
B. Furnace temperature
C. External colour
D. Sheet thickness only
Answer: A. Internal dimensions
Explanation: A mandrel supports and controls the internal surface during tube drawing.
Q74. In extrusion, the material is subjected mainly to:
A. Compressive stress
B. Tensile stress only
C. Pure bending
D. Impact only
Answer: A. Compressive stress
Explanation: The ram applies compressive force to push the billet through the die.
Q75. In drawing, the material is subjected significantly to:
A. Tensile stress
B. Pure compression only
C. Bending only
D. Impact only
Answer: A. Tensile stress
Explanation: The drawing force pulls the workpiece through the die.
Q76. Which process can produce an aluminium window-frame profile?
A. Extrusion
B. Punching only
C. Deep drawing only
D. Open-die forging only
Answer: A. Extrusion
Explanation: Extrusion is widely used for long aluminium profiles with complex constant cross-sections.
Q77. In indirect extrusion, friction between billet and container is generally:
A. Lower than in direct extrusion
B. Higher than in direct extrusion
C. Always zero
D. Unrelated to the process
Answer: A. Lower than in direct extrusion
Explanation: The billet does not slide relative to the container in the same manner as in direct extrusion.
Q78. Which process is more appropriate for reducing the diameter of a wire?
A. Wire drawing
B. Forging
C. Casting
D. Deep drawing
Answer: A. Wire drawing
Explanation: Wire drawing is specifically designed for producing smaller wire diameters.
Q79. Which process is generally associated with pushing a billet through a die?
A. Extrusion
B. Drawing
C. Bending
D. Shearing
Answer: A. Extrusion
Explanation: Extrusion uses compressive force to push material through the die.
Q80. Which process is generally associated with pulling a workpiece through a die?
A. Drawing
B. Extrusion
C. Rolling
D. Forging
Answer: A. Drawing
Explanation: Drawing uses tensile pulling force to pass the material through a die.
MCQ 81–100: Sheet Metal Processes
Q81. Sheet metal working is generally performed on:
A. Thin sheets and strips
B. Molten metal only
C. Sand
D. Wooden blocks
Answer: A. Thin sheets and strips
Explanation: Sheet-metal processes shape and cut relatively thin metal stock.
Q82. Which operation separates sheet metal by shear?
A. Shearing
B. Forging
C. Extrusion
D. Rolling only
Answer: A. Shearing
Explanation: Shearing separates sheet material through localized shear deformation.
Q83. In blanking, the cut-out portion is:
A. The desired component
B. Always scrap
C. The punch
D. The die
Answer: A. The desired component
Explanation: The blank is the required product in blanking.
Q84. In punching, the removed portion is generally:
A. Scrap
B. The final sheet
C. The die
D. The punch
Answer: A. Scrap
Explanation: The hole is the desired feature, while the removed slug is generally discarded.
Q85. The tool that enters the sheet during punching is:
A. Punch
B. Riser
C. Core
D. Runner
Answer: A. Punch
Explanation: The punch moves relative to the die and cuts the sheet.
Q86. Clearance in a punching operation is provided between:
A. Punch and die
B. Riser and runner
C. Core and mould box
D. Hammer and anvil only
Answer: A. Punch and die
Explanation: Proper punch-die clearance is essential for good cutting quality and tool life.
Q87. Excessive clearance in blanking may produce:
A. Poor edge quality
B. Perfect edge quality always
C. No cutting
D. No deformation
Answer: A. Poor edge quality
Explanation: Incorrect clearance can increase burr formation and reduce cut quality.
Q88. Bending is primarily used to:
A. Change the shape/angle of sheet metal
B. Remove large amounts of material
C. Melt sheet metal
D. Cast a component
Answer: A. Change the shape/angle of sheet metal
Explanation: Bending plastically deforms the sheet around an axis.

Q89. Springback is particularly important in:
A. Sheet-metal bending
B. Sand casting
C. Cupola operation
D. Welding electrode coating
Answer: A. Sheet-metal bending
Explanation: Elastic recovery after bending changes the final angle and shape.
Q90. One method used to compensate for springback is:
A. Over-bending
B. Removing all tooling
C. Reducing all forces to zero
D. Increasing sheet thickness indefinitely
Answer: A. Over-bending
Explanation: The material can be bent slightly beyond the required angle so that elastic recovery brings it closer to the desired final angle.
Q91. Deep drawing uses:
A. Punch and die
B. Only rolling rolls
C. Only a hammer
D. A cupola
Answer: A. Punch and die
Explanation: The punch pushes the sheet blank into the die cavity to form the desired hollow shape.
Q92. A blank holder in deep drawing is used mainly to:
A. Control material flow and reduce wrinkling
B. Melt the blank
C. Increase casting shrinkage
D. Cut the blank completely
Answer: A. Control material flow and reduce wrinkling
Explanation: The blank holder controls the flange region during drawing.
Q93. Wrinkling in deep drawing is associated mainly with:
A. Compressive stresses in the flange
B. Tensile stress only
C. Melting
D. Welding
Answer: A. Compressive stresses in the flange
Explanation: Compressive circumferential stresses can cause the flange to buckle and form wrinkles.
Q94. Excessive tensile stress in deep drawing can cause:
A. Tearing
B. Wrinkling only
C. Embossing
D. Coining
Answer: A. Tearing
Explanation: Excessive drawing force can exceed the material’s forming capability and cause tearing.
Q95. Embossing is used to produce:
A. Raised or recessed patterns
B. Deep holes only
C. Cast cavities
D. Forging flash
Answer: A. Raised or recessed patterns
Explanation: Embossing forms localized raised or recessed features in sheet metal.
Q96. Coining involves:
A. High compressive pressure
B. Only tensile loading
C. Melting
D. Sand moulding
Answer: A. High compressive pressure
Explanation: Coining uses high pressure between dies to produce detailed impressions.
Q97. Which operation is used to produce a hollow cylindrical component from sheet metal?
A. Deep drawing
B. Rolling
C. Wire drawing
D. Open-die forging
Answer: A. Deep drawing
Explanation: Deep drawing converts a flat blank into a hollow shape.
Q98. Which of the following is NOT normally classified as a sheet-metal cutting operation?
A. Punching
B. Blanking
C. Shearing
D. Deep drawing
Answer: D. Deep drawing
Explanation: Deep drawing is a forming operation rather than a cutting operation.

Q99. Which operation produces the required blank by cutting it from a sheet?
A. Blanking
B. Drawing
C. Forging
D. Extrusion
Answer: A. Blanking
Explanation: The separated blank becomes the desired product.
Q100. Which operation produces a hole as the desired result?
A. Punching
B. Blanking
C. Rolling
D. Extrusion
Answer: A. Punching
Explanation: In punching, the hole is the required feature and the removed slug is generally scrap.
CHAPTER 6 — EXAM REVISION CAPSULE
Remember these pairs:
Rolling → Rolls
Forging → Compression
Extrusion → Push through die
Drawing → Pull through die
Blanking → Blank is product
Punching → Hole is product
Deep Drawing → Cup/hollow component
Bending → Sheet angle changes
Embossing → Raised/recessed design
Coining → High-pressure impression
Hot Working → Recrystallization during deformation
Cold Working → Work hardening
Springback → Elastic recovery
Important Numerical Formulae
Draft in Rolling
Percentage Reduction
Extrusion Ratio
WHERE:
= Initial cross-sectional area
= Final cross-sectional area
CHAPTER 7 — WELDING TECHNOLOGY

7.1 Introduction
Welding is one of the most important permanent joining processes used in manufacturing and workshop technology.
It is extensively used in:
Automobile manufacturing
Railway equipment
Bridges
Pressure vessels
Pipelines
Shipbuilding
Structural fabrication
Machine frames
Boilers
Storage tanks
Aerospace components
Unlike temporary fastening methods such as nuts and bolts, welding generally produces a permanent joint.
7.2 Definition of Welding
Welding is a permanent joining process in which two or more materials are joined by applying heat, pressure, or a combination of heat and pressure, with or without the use of filler material.
Key Concept
Welding → Permanent joining → Heat/Pressure → Joint
7.3 Objectives of Welding
The main objectives are:
To permanently join two or more components.
To produce a strong joint.
To fabricate complex structures.
To repair damaged components.
To manufacture large structures economically.
To join similar or, with suitable processes, dissimilar materials.
7.4 Welding vs Brazing vs Soldering
These three processes are frequently asked in competitive examinations.
Process Basic Principle Filler Metal
Welding Base metals are joined by heat/pressure May or may not be used
Brazing Filler metal melts above 450°C Used
Soldering Filler metal melts below 450°C Used

Important
Brazing: Filler metal melting temperature is above 450°C but below the melting temperature of the base metals.
Soldering: Filler metal melting temperature is below 450°C.
7.5 Classification of Welding Processes
Welding processes can broadly be classified as:
A. Fusion Welding
The base metal is melted during joining.
Examples:
Gas welding
Arc welding
Thermit welding
Laser beam welding
Electron beam welding
B. Solid-State Welding
The base metals are joined without melting the base material.
Examples:
Forge welding
Friction welding
Diffusion welding
Ultrasonic welding
Explosive welding
7.6 Arc Welding
Arc welding uses an electric arc to generate heat for melting the workpiece and, where applicable, the electrode/filler.
The temperature of an electric arc is extremely high and is sufficient to melt many engineering metals.
7.7 Electric Arc
An electric arc is established between:
Electrode and workpiece, or
Two electrodes
The electrical energy is converted into heat energy.
Basic Principle
Electrical energy → Arc → Heat → Melting → Weld joint
7.8 Shielded Metal Arc Welding (SMAW)
SMAW is commonly known as:
Manual Metal Arc Welding (MMA/MMAW)
It uses a flux-coated consumable electrode.
Main Features
Electrode is consumable.
Electrode coating provides shielding.
Slag is formed.
Suitable for many fabrication applications.
Relatively portable.
7.9 Electrode
An electrode is the component through which electric current is supplied to establish the arc.
Electrodes may be:
Consumable
Non-consumable
Consumable Electrode
The electrode melts and becomes part of the weld metal.
Example:
SMAW electrode
Non-Consumable Electrode
The electrode does not normally become part of the weld.
Example:
TIG tungsten electrode
7.10 Flux
Flux is a material used during welding to assist in removing/preventing oxides and to help protect the molten weld pool.
Functions include:
Preventing atmospheric contamination
Removing oxides
Forming protective slag in relevant processes
Improving weld quality
7.11 Slag
Slag is a non-metallic layer formed over the weld during processes such as shielded metal arc welding.
It protects the molten/solidifying weld metal from atmospheric contamination.
After welding, slag may need to be removed.
7.12 Gas Welding
Gas welding uses heat generated by combustion of a fuel gas with oxygen or another oxidizer.
The most common traditional gas-welding process is:
Oxy-acetylene welding
7.13 Oxy-Acetylene Welding
Oxy-acetylene welding uses:
Oxygen
Acetylene
The gases are mixed and burned at the welding torch.
Applications
Sheet-metal work
Repair work
Pipe work
Cutting
Maintenance operations
7.14 Welding Flame
In oxy-acetylene welding, three important flame types are:
Neutral flame
Carburizing/reducing flame
Oxidizing flame
7.15 Neutral Flame
A neutral flame has approximately balanced oxygen and acetylene proportions.
It has:
Inner cone
Outer envelope
It is widely used for welding many steels and other metals.
Remember
Neutral flame → General-purpose flame
7.16 Carburizing Flame
A carburizing flame is also called a:
Reducing flame
It contains excess acetylene relative to oxygen.
It can introduce carbon-rich/reducing conditions and is useful for selected materials and applications.
7.17 Oxidizing Flame
An oxidizing flame contains excess oxygen.
It is used for specific materials such as certain copper alloys and is generally unsuitable for ordinary welding of steels because excessive oxidation can be harmful.
7.18 TIG Welding
TIG = Tungsten Inert Gas Welding

The modern process designation is:

Gas Tungsten Arc Welding (GTAW)

It uses a non-consumable tungsten electrode and an inert shielding gas.

Common shielding gases include:

Argon

Helium

Important

TIG → Tungsten electrode → Non-consumable

7.19 Advantages of TIG Welding

High-quality welds

Excellent control

Clean welds

No slag from flux-coated electrode

Suitable for thin materials

Suitable for many non-ferrous metals

7.20 MIG Welding

MIG = Metal Inert Gas Welding

It is commonly associated with:

Gas Metal Arc Welding (GMAW)

A continuously fed consumable wire electrode is used.

The shielding gas protects the weld pool from atmospheric contamination.

Important

MIG → Consumable wire electrode

7.21 MIG vs TIG

Feature	MIG	TIG
Electrode	Consumable wire	Non-consumable tungsten
Wire feed	Continuous	Separate filler may be used
Productivity	Generally high	Generally lower
Control	Good	Excellent
Typical use	Production	High-quality precision welding

7.22 Resistance Welding

Resistance welding generates heat due to the electrical resistance of the workpiece.

The heat generated is related to:

Where:

= heat

= current

= electrical resistance

= time

Principle

Electrical resistance → Heat → Pressure → Weld

7.23 Spot Welding

Spot welding is a resistance-welding process in which overlapping sheets are joined at discrete spots.

It is extensively used in:

Automobile bodies

Sheet-metal assemblies

Appliances

7.24 Seam Welding

Seam welding produces a series of overlapping weld nuggets, often forming a continuous or leak-tight seam.

It uses wheel-shaped electrodes.

7.25 Projection Welding

In projection welding, localized projections on one or both components concentrate current and pressure.

It is useful for:

Nuts

Fasteners

Sheet assemblies

7.26 Butt Welding

Butt welding joins components placed approximately end-to-end.

Resistance butt welding is one important form.

7.27 Thermit Welding

Thermit welding uses the heat generated by an exothermic chemical reaction.

A thermit mixture commonly involves:

Aluminium + Metal oxide

The reaction produces intense heat and molten metal.

Application

A famous application is:

Rail joining

7.28 Friction Welding

Friction welding is a solid-state welding process.

Heat is generated by friction between surfaces in relative motion.

After sufficient heating, pressure is applied to form the joint.

Important

Friction welding → Solid-state process

7.29 Ultrasonic Welding

Ultrasonic welding uses:

High-frequency mechanical vibrations

Pressure

It is a solid-state joining process.

It is commonly used for:

Thin sheets

Electrical/electronic components

Certain plastics and metals

7.30 Diffusion Welding

Diffusion welding is a solid-state process in which surfaces are joined under:

Pressure

Elevated temperature

Controlled conditions

Bonding occurs through atomic diffusion across the interface.

7.31 Welding Joints

Common welding joint types include:

Butt joint
Lap joint
T-joint
Corner joint
Edge joint

7.32 Butt Joint

In a butt joint, two components are placed approximately:

In the same plane, edge to edge.

7.33 Lap Joint

In a lap joint, two sheets:

Overlap each other.

7.34 T-Joint

A T-joint is formed when one component is positioned approximately perpendicular to another, producing a T-shaped configuration.

7.35 Corner Joint

A corner joint joins two components at a corner.

7.36 Edge Joint

In an edge joint, adjacent edges of two sheets are joined.

7.37 Welding Positions

Common welding positions are:

Flat

Horizontal

Vertical

Overhead

Most difficult among common positions

Overhead welding generally requires greater skill and control.

7.38 Weld Defects

Important welding defects include:

Porosity

Cracks

Undercut

Slag inclusion

Lack of fusion

Lack of penetration

Spatter

Distortion

Burn-through

7.39 Porosity

Porosity consists of cavities or gas pores trapped in the weld metal.

Possible causes include:

Moisture

Contamination

Inadequate shielding

Improper welding parameters

7.40 Undercut

Undercut is a groove formed along the edge/toe of a weld that is not properly filled with weld metal.

Possible causes:

Excessive current

Excessive travel speed

Incorrect electrode angle

7.41 Slag Inclusion

Slag inclusion occurs when non-metallic slag becomes trapped within the weld metal.

It may result from:

Inadequate cleaning between passes

Improper welding technique

Incorrect electrode manipulation

7.42 Lack of Fusion

Lack of fusion occurs when weld metal fails to properly fuse with:

Base metal, or

Previous weld bead

7.43 Lack of Penetration

Lack of penetration means that the weld does not extend sufficiently into the joint root.

7.44 Welding Distortion

Distortion occurs because of:

Uneven heating and cooling

Different regions expand and contract differently, producing dimensional changes.

7.45 Welding Safety

Important safety precautions include:

Use proper welding helmet.

Protect eyes from arc radiation.

Wear suitable gloves.

Use protective clothing.

Ensure proper ventilation.

Keep flammable materials away.

Inspect cables and equipment.

Handle gas cylinders correctly.

7.46 Quick Revision Table

Topic	Key Point
Welding	Permanent joining
SMAW	Consumable flux-coated electrode
TIG/GTAW	Non-consumable tungsten
MIG/GMAW	Consumable wire
Gas welding	Combustion of fuel gas
Neutral flame	Balanced oxygen-acetylene condition
Resistance welding
Spot welding	Individual weld spots
Seam welding	Continuous/overlapping seam
Thermit welding	Exothermic reaction
Friction welding	Solid-state
Ultrasonic welding	High-frequency vibration
Butt joint	Edge-to-edge
Lap joint	Overlapping sheets
T-joint	T-shaped arrangement
Porosity	Gas cavities
Undercut	Groove at weld toe
Slag inclusion	Slag trapped in weld
Distortion	Uneven heating/cooling

Q1. Welding is generally classified as a:

A. Temporary joining process
B. Permanent joining process
C. Measuring process
D. Surface finishing process

Answer: B. Permanent joining process

Explanation: Welding normally produces a permanent joint between components.

Q2. Which of the following is a fusion welding process?

A. Arc welding
B. Friction welding
C. Diffusion welding
D. Ultrasonic welding

Answer: A. Arc welding

Explanation: In arc welding, the base material is melted to form the joint.

Q3. Which of the following is a solid-state welding process?

A. Gas welding
B. Arc welding
C. Friction welding
D. Thermit welding

Answer: C. Friction welding

Explanation: Friction welding produces a joint without melting the base materials.

Q4. TIG welding uses:

A. Consumable tungsten electrode
B. Non-consumable tungsten electrode
C. Carbon dioxide electrode only
D. Copper electrode only

Answer: B. Non-consumable tungsten electrode

Explanation: TIG/GTAW uses a tungsten electrode that normally does not melt into the weld.

Q5. MIG welding generally uses:

A. Consumable wire electrode
B. Non-consumable tungsten electrode
C. No electrode
D. Carbon rod only

Answer: A. Consumable wire electrode

Explanation: GMAW/MIG uses a continuously fed consumable wire electrode.

Q6. The shielding gas commonly used in TIG welding is:

A. Argon
B. Oxygen only
C. Hydrogen only
D. Chlorine

Answer: A. Argon

Explanation: Argon is widely used as an inert shielding gas in TIG welding.

Q7. SMAW uses:

A. Flux-coated consumable electrode
B. Non-consumable tungsten only
C. Laser beam
D. Friction wheel

Answer: A. Flux-coated consumable electrode

Explanation: Shielded Metal Arc Welding uses a flux-coated consumable electrode.

Q8. The primary function of shielding gas is to:

A. Protect the molten weld pool from atmospheric contamination
B. Increase rusting
C. Cool the electrode completely
D. Produce mechanical chips

Answer: A. Protect the molten weld pool from atmospheric contamination

Explanation: Shielding prevents harmful reactions between the molten metal and atmospheric gases.

Q9. The heat generated in resistance welding is proportional to:

A.
B.
C.
D.

Answer: A.

Explanation:

This is the fundamental Joule-heating relationship used in resistance welding.

Q10. Spot welding is a type of:

A. Resistance welding
B. Gas welding
C. Thermit welding
D. Friction welding

Answer: A. Resistance welding

Explanation: Spot welding generates heat from electrical resistance and uses electrode pressure to make localized welds.

Q11. Seam welding commonly uses:

A. Wheel-shaped electrodes
B. Tungsten rods only
C. Gas nozzles only
D. Hammer dies

Answer: A. Wheel-shaped electrodes

Explanation: Rotating wheel electrodes are characteristic of resistance seam welding.

Q12. Thermit welding is based on:

A. Exothermic chemical reaction
B. Ultrasonic vibration
C. Friction only
D. Resistance heating only

Answer: A. Exothermic chemical reaction

Explanation: Thermit welding uses heat released by a highly exothermic chemical reaction.

Q13. Thermit welding is commonly associated with joining:

A. Railway rails
B. Thin plastic films
C. Wooden sheets
D. Glass fibres

Answer: A. Railway rails

Explanation: Thermit welding is traditionally used for field joining and repair of railway rails.

Q14. Friction welding is classified as:

A. Solid-state welding
B. Fusion welding
C. Gas welding
D. Arc cutting

Answer: A. Solid-state welding

Explanation: The materials are joined without melting the base metals.

Q15. In brazing, the filler metal melts at a temperature:

A. Below 450°C
B. Above 450°C but below the melting temperature of the base metals
C. Above the melting temperature of the base metals
D. Exactly 0°C

Answer: B. Above 450°C but below the melting temperature of the base metals

Explanation: This temperature criterion distinguishes conventional brazing from soldering.

Q16. Soldering generally uses a filler metal melting below:

A. 100°C
B. 250°C
C. 450°C
D. 1000°C

Answer: C. 450°C

Explanation: Conventional classification defines soldering as using filler metal with a melting temperature below 450°C.

Q17. A joint in which two sheets overlap each other is called:

A. Butt joint
B. Lap joint
C. T-joint
D. Edge joint

Answer: B. Lap joint

Explanation: In a lap joint, one component overlaps the other.

Q18. Which welding position is generally considered most difficult among the standard basic positions?

A. Flat
B. Horizontal
C. Vertical
D. Overhead

Answer: D. Overhead

Explanation: Overhead welding requires greater control because molten metal tends to fall under gravity.

Q19. Gas cavities in a weld are known as:

A. Porosity
B. Undercut
C. Overlap
D. Distortion

Answer: A. Porosity

Explanation: Porosity results from gas becoming trapped in the solidifying weld metal.

Q20. A groove formed at the toe of a weld is called:

A. Porosity
B. Undercut
C. Slag inclusion
D. Crack

Answer: B. Undercut

Explanation: Undercut is a groove along the weld toe that reduces the effective section of the joint.

MCQ 21–40: Arc Welding & Electrodes

Q21. In arc welding, the heat required for welding is generated by:

A. Chemical reaction only
B. Electric arc
C. Mechanical friction only
D. Steam pressure

Answer: B. Electric arc

Explanation: An electric arc produces intense heat that melts the base metal and/or electrode.

Q22. Which of the following is a consumable electrode process?

A. TIG
B. SMAW
C. Carbon arc welding
D. Plasma arc welding with non-consumable electrode

Answer: B. SMAW

Explanation: Shielded Metal Arc Welding uses a flux-coated consumable electrode that melts during welding.

Practice

Q23. The coating on a shielded metal arc welding electrode primarily helps to:

A. Increase electrical resistance of the workpiece
B. Provide shielding and form slag
C. Prevent melting of the electrode
D. Remove the base metal

Answer: B. Provide shielding and form slag

Explanation: Electrode coating produces gases and slag that protect the molten weld pool.

Q24. The core wire of a coated electrode mainly acts as:

A. Insulator
B. Filler metal and current carrier
C. Coolant
D. Shielding gas

Answer: B. Filler metal and current carrier

Explanation: The metal core conducts welding current and melts to contribute to the weld.

Q25. The arc length in arc welding is the distance between:

A. Electrode and workpiece
B. Two workpieces
C. Welding machine and electrode
D. Ground and machine

Answer: A. Electrode and workpiece

Explanation: Arc length refers to the distance across the electrical arc between the electrode tip and workpiece.

Q26. Excessively long arc length may result in:

A. Increased spatter and poor weld quality
B. Perfect penetration in all cases
C. No arc formation
D. Zero heat input

Answer: A. Increased spatter and poor weld quality

Explanation: Excessive arc length can make the arc unstable and increase spatter and atmospheric contamination.

Q27. If the welding current is excessively high, it may cause:

A. Excessive penetration and undercut
B. No melting
C. Zero heat generation
D. Complete elimination of distortion

Answer: A. Excessive penetration and undercut

Explanation: Excessive current increases heat input and can cause excessive melting, undercut and burn-through.

Q28. Welding current is measured in:

A. Volt
B. Ampere
C. Ohm
D. Watt-hour

Answer: B. Ampere

Explanation: Welding current is expressed in amperes (A).

Q29. Welding voltage is measured in:

A. Ampere
B. Volt
C. Ohm
D. Coulomb

Answer: B. Volt

Explanation: Arc voltage is measured in volts.

Q30. The electrode holder in manual arc welding is used to:

A. Hold the electrode and conduct current
B. Supply shielding gas only
C. Cool the weld pool
D. Cut the workpiece

Answer: A. Hold the electrode and conduct current

Explanation: The electrode holder mechanically holds the electrode and provides electrical connection.

Q31. The welding cable carries:

A. Welding current
B. Cooling water only
C. Acetylene only
D. Slag

Answer: A. Welding current

Explanation: Welding cables connect the power source to the electrode holder and workpiece.

Q32. The return cable in arc welding connects the:

A. Workpiece to the welding power source
B. Electrode to gas cylinder
C. Torch to regulator only
D. Die to punch

Answer: A. Workpiece to the welding power source

Explanation: The return circuit completes the electrical path required for arc welding.

Q33. Arc welding power sources may provide:

A. AC or DC
B. Only hydraulic pressure
C. Only compressed air
D. Only steam

Answer: A. AC or DC

Explanation: Depending on the welding process and application, alternating or direct current can be used.

Q34. DC welding allows control of:

A. Polarity
B. Atmospheric pressure
C. Room temperature
D. Metal density

Answer: A. Polarity

Explanation: With DC, the electrode can be connected as positive or negative depending on the required welding characteristics.

Q35. DCEP means:

A. Direct Current Electrode Positive
B. Direct Current Electrode Pressure
C. Direct Current Energy Process
D. Direct Current External Power

Answer: A. Direct Current Electrode Positive

Explanation: In DCEP, the electrode is connected to the positive terminal of the DC power source.

Q36. DCEN means:

A. Direct Current Electrode Negative
B. Direct Current Energy Neutral
C. Direct Current Electrode Normal
D. Direct Current External Negative

Answer: A. Direct Current Electrode Negative

Explanation: In DCEN, the electrode is connected to the negative terminal.

Q37. Which electrode is used in TIG welding?

A. Tungsten
B. Mild steel wire only
C. Copper wire only
D. Aluminium strip only

Answer: A. Tungsten

Explanation: TIG uses a non-consumable tungsten electrode.

Q38. The main function of shielding in arc welding is to protect the molten metal from:

A. Atmospheric gases
B. Mechanical vibration
C. Cutting forces
D. Rolling forces

Answer: A. Atmospheric gases

Explanation: Oxygen and nitrogen from the atmosphere can adversely affect weld quality.

Q39. Which of the following is NOT normally a function of electrode coating?

A. Shielding
B. Slag formation
C. Arc stabilization
D. Increasing workpiece weight

Answer: D. Increasing workpiece weight

Explanation: Electrode coating can provide shielding, slag and arc-stabilizing compounds, but it does not serve to increase workpiece weight.

Q40. Slag formed during SMAW should generally be:

A. Removed after welding/pass completion as appropriate
B. Permanently left on every weld
C. Melted into the workpiece manually
D. Used as cutting fluid

Answer: A. Removed after welding/pass completion as appropriate

Explanation: Slag must be removed where required, particularly between passes, to avoid slag inclusion.

MCQ 41–60: TIG, MIG & Gas Welding

Q41. TIG welding is also known as:

A. GTAW
B. GMAW
C. SMAW
D. SAW

Answer: A. GTAW

Explanation: TIG corresponds to Gas Tungsten Arc Welding (GTAW).

Q42. MIG welding is commonly classified as:

A. GMAW
B. GTAW
C. SAW
D. PAW only

Answer: A. GMAW

Explanation: MIG is commonly used to describe Gas Metal Arc Welding.

Q43. In MIG welding, the electrode is:

A. Continuously fed consumable wire
B. Non-consumable tungsten
C. Carbon block only
D. Ceramic rod

Answer: A. Continuously fed consumable wire

Explanation: A continuous wire electrode serves as both electrode and filler metal.

Q44. One major advantage of MIG welding is:

A. High deposition rate
B. No need for shielding
C. No electrical power required
D. No electrode consumption

Answer: A. High deposition rate

Explanation: Continuous wire feeding enables high productivity.

Q45. TIG welding is especially suitable where:

A. High-quality and precise weld control is required
B. Maximum slag production is required
C. No shielding is required
D. Only impact loading is used

Answer: A. High-quality and precise weld control is required

Explanation: TIG offers excellent control of the arc and weld pool.

Q46. The most common shielding gases for TIG include:

A. Argon and helium
B. Oxygen and hydrogen
C. Chlorine and fluorine
D. Nitrogen only

Answer: A. Argon and helium

Explanation: Argon and helium are inert gases widely used for GTAW/TIG.

Q47. In MIG welding, shielding gas is supplied through the:

A. Welding gun/torch
B. Hammer
C. Die
D. Electrode coating only

Answer: A. Welding gun/torch

Explanation: Shielding gas flows through the welding gun nozzle around the arc and weld pool.

Q48. A major disadvantage of TIG compared with MIG is generally:

A. Lower productivity
B. No arc control
C. No shielding gas
D. No usable electrode

Answer: A. Lower productivity

Explanation: TIG is highly controllable but generally has a lower deposition rate than continuous-wire MIG.

Q49. Oxy-acetylene welding uses:

A. Oxygen and acetylene
B. Nitrogen and oxygen
C. Hydrogen and nitrogen
D. Argon and helium

Answer: A. Oxygen and acetylene

Explanation: The mixture of oxygen and acetylene produces the welding flame.

Q50. The main components of a conventional oxy-acetylene welding setup include:

A. Gas cylinders, regulators, hoses and torch
B. Rolling mill and furnace only
C. Punch and die only
D. Hammer and anvil only

Answer: A. Gas cylinders, regulators, hoses and torch

Explanation: These components control and deliver oxygen and fuel gas to the welding torch.

Q51. The regulator in gas welding is used to:

A. Control gas pressure
B. Produce an electric arc
C. Remove slag
D. Cut threads

Answer: A. Control gas pressure

Explanation: Regulators reduce cylinder pressure to the required working pressure.

Q52. The purpose of a welding torch is to:

A. Mix and control gases to produce the flame
B. Measure weld hardness
C. Roll sheet metal
D. Produce forging flash

Answer: A. Mix and control gases to produce the flame

Explanation: The torch controls the flow and mixing of oxygen and fuel gas.

Q53. A neutral oxy-acetylene flame has:

A. Approximately balanced oxygen and acetylene
B. Large excess oxygen
C. Large excess acetylene only
D. No oxygen

Answer: A. Approximately balanced oxygen and acetylene

Explanation: A neutral flame has approximately balanced proportions and is widely used for general welding.

Q54. An oxidizing flame contains:

A. Excess oxygen
B. Excess acetylene
C. No oxygen
D. Only nitrogen

Answer: A. Excess oxygen

Explanation: Increasing oxygen relative to acetylene produces an oxidizing flame.

Q55. A carburizing flame is also called:

A. Reducing flame
B. Oxidizing flame
C. Neutral flame
D. Plasma flame

Answer: A. Reducing flame

Explanation: A carburizing flame contains excess fuel and has a reducing/carburizing character.

Q56. The most commonly used general-purpose flame for oxy-acetylene welding is:

A. Neutral flame
B. Oxidizing flame
C. Strongly carburizing flame
D. Plasma flame

Answer: A. Neutral flame

Explanation: Neutral flame is suitable for welding many common engineering materials.

Q57. Oxygen cylinders should generally be kept away from:

A. Oil and grease contamination
B. Clean metal surfaces
C. Welding helmets
D. Steel plates

Answer: A. Oil and grease contamination

Explanation: Oxygen supports combustion strongly, so contact with oil/grease can create a serious fire hazard.

Q58. Acetylene cylinders should be:

A. Handled and stored according to approved safety procedures
B. Exposed to uncontrolled heat
C. Placed beside open flames
D. Used without regulators

Answer: A. Handled and stored according to approved safety procedures

Explanation: Fuel-gas cylinders require controlled storage, handling and pressure regulation.

Q59. In gas welding, the flame provides:

A. Heat for melting the joint region
B. Mechanical pressure only
C. Electrical current only
D. Cutting chips

Answer: A. Heat for melting the joint region

Explanation: Combustion of the gases generates the heat required for fusion welding.

Q60. Gas welding is particularly useful for:

A. Repair and relatively thin-material applications
B. Only very large forgings
C. High-speed rolling
D. Powder metallurgy

Answer: A. Repair and relatively thin-material applications

Explanation: Gas welding provides relatively controllable heat and is widely used for maintenance and repair work.

MCQ 61–80: Resistance Welding & Welding Joints

Q61. Resistance welding generates heat mainly because of:

A. Electrical resistance
B. Chemical combustion
C. Mechanical cutting
D. Laser reflection only

Answer: A. Electrical resistance

Explanation: Electrical current passing through resistance generates heat according to .

Q62. The basic heat equation for resistance welding is:

A.
B.
C.
D.

Answer: A.

Explanation: This is Joule’s law of heating.

Q63. Spot welding is most commonly used for:

A. Overlapping sheet metals
B. Large solid shafts
C. Sand casting
D. Thread cutting

Answer: A. Overlapping sheet metals

Explanation: Spot welding produces localized weld nuggets between overlapping sheets.

Q64. The electrodes used in resistance spot welding are generally:

A. Copper-alloy electrodes
B. Wooden electrodes
C. Tungsten cutting tools only
D. Ceramic electrodes only

Answer: A. Copper-alloy electrodes

Explanation: Copper alloys provide good electrical and thermal conductivity along with suitable strength.

Q65. In resistance spot welding, pressure is applied by:

A. Electrodes
B. Gas cylinder
C. Welding helmet
D. Slag hammer

Answer: A. Electrodes

Explanation: The electrodes press the sheets together while current passes through the joint.

Q66. Seam welding uses:

A. Wheel electrodes
B. Flat dies only
C. Hammer blows
D. Gas nozzles only

Answer: A. Wheel electrodes

Explanation: Rotating wheel electrodes create a sequence of overlapping weld spots.

Q67. Projection welding differs from spot welding because:

A. Projections concentrate current and pressure
B. No current is used
C. No pressure is used
D. It requires a gas flame

Answer: A. Projections concentrate current and pressure

Explanation: Designed projections localize the welding action.

Q68. Resistance welding generally requires:

A. Electrical current and electrode pressure
B. Only a gas flame
C. Only a hammer
D. Only filler rod

Answer: A. Electrical current and electrode pressure

Explanation: Heat is generated electrically and pressure ensures proper contact and forging of the weld region.

Q69. Which joint has two plates approximately in the same plane?

A. Butt joint
B. Lap joint
C. T-joint
D. Corner joint

Answer: A. Butt joint

Explanation: Butt joints join members edge-to-edge.

Q70. Which joint has overlapping plates?

A. Lap joint
B. Butt joint
C. Edge joint
D. T-joint

Answer: A. Lap joint

Explanation: One sheet overlaps another in a lap joint.

Q71. A T-joint has approximately:

A. 90° intersection between members
B. 0° intersection
C. 180° overlap only
D. Circular intersection

Answer: A. 90° intersection between members

Explanation: One component is generally positioned perpendicular to another, creating a T configuration.

Q72. A corner joint is formed:

A. At the corner of two members
B. Only at the centre of a sheet
C. Between two wires only
D. Inside a casting mould

Answer: A. At the corner of two members

Explanation: The members meet at a corner configuration.

Q73. Which joint is commonly used when two plates are to be joined edge-to-edge?

A. Butt joint
B. Lap joint
C. Projection joint
D. Spot joint only

Answer: A. Butt joint

Explanation: Butt joints are specifically intended for edge-to-edge joining.

Q74. Which of the following is NOT a standard basic welding position?

A. Flat
B. Horizontal
C. Vertical
D. Circular

Answer: D. Circular

Explanation: Flat, horizontal, vertical and overhead are standard basic welding positions.

Q75. Overhead welding means welding:

A. From below a joint
B. Only on a horizontal plate
C. Under water only
D. Inside a furnace

Answer: A. From below a joint

Explanation: In overhead welding, the weld is made on the underside of the workpiece.

Q76. Welding position affects:

A. Welder technique and molten-metal control
B. Atomic number
C. Material density
D. Melting point permanently

Answer: A. Welder technique and molten-metal control

Explanation: Gravity affects the molten pool differently in different positions.

Q77. Which resistance welding process uses individual localized welds?

A. Spot welding
B. Seam welding
C. Butt welding only
D. Flash welding only

Answer: A. Spot welding

Explanation: Spot welding creates discrete weld nuggets at selected locations.

Q78. Which resistance process can produce a continuous leak-tight joint?

A. Seam welding
B. Spot welding only
C. Projection welding only
D. Upset forging

Answer: A. Seam welding

Explanation: Overlapping weld nuggets can form a continuous seam suitable for leak-resistant applications.

Q79. Projection welding is commonly used for joining:

A. Nuts to sheet metal
B. Railway rails by thermit only
C. Plastic films only
D. Wooden blocks

Answer: A. Nuts to sheet metal

Explanation: Projections on nuts or components concentrate the current and pressure during welding.

Q80. Resistance welding is particularly suitable for:

A. High-volume sheet-metal production
B. Only one-off heavy forgings
C. Sand mould preparation
D. Gear cutting

Answer: A. High-volume sheet-metal production

Explanation: Resistance welding is fast and readily automated, making it suitable for mass production.

MCQ 81–100: Welding Defects, Inspection & Safety

Q81. Gas cavities trapped inside weld metal are called:

A. Porosity
B. Undercut
C. Overlap
D. Distortion

Answer: A. Porosity

Explanation: Porosity consists of voids caused by trapped gas.

Q82. Slag trapped inside the weld is called:

A. Slag inclusion
B. Porosity
C. Undercut
D. Burn-through

Answer: A. Slag inclusion

Explanation: Non-metallic slag becomes trapped within the weld metal.

Q83. Failure of weld metal to properly fuse with the base metal is:

A. Lack of fusion
B. Porosity
C. Spatter
D. Distortion

Answer: A. Lack of fusion

Explanation: Lack of fusion occurs when the weld metal does not properly bond with the parent material.

Q84. Insufficient depth of fusion at the root is known as:

A. Lack of penetration
B. Undercut
C. Porosity
D. Cratering

Answer: A. Lack of penetration

Explanation: The weld does not extend sufficiently into the root of the joint.

Q85. A groove along the weld toe is called:

A. Undercut
B. Porosity
C. Slag inclusion
D. Crack

Answer: A. Undercut

Explanation: Undercut removes base metal at the weld toe without adequate filling.

Q86. Uneven heating and cooling during welding may cause:

A. Distortion
B. Increased density
C. Perfect dimensional accuracy
D. No residual stress

Answer: A. Distortion

Explanation: Local thermal expansion and contraction produce distortion and residual stresses.

Q87. Excessive welding current may contribute to:

A. Undercut and excessive penetration
B. No melting
C. Zero heat input
D. No weld formation

Answer: A. Undercut and excessive penetration

Explanation: Excessive current produces excessive heat and can damage the joint edges.

Q88. Moisture in welding electrodes can contribute to:

A. Hydrogen-related weld problems
B. Improved weld quality in every case
C. Zero porosity
D. Lower atmospheric contamination

Answer: A. Hydrogen-related weld problems

Explanation: Moisture can introduce hydrogen into the weld, increasing the risk of cracking in susceptible materials.

Q89. Weld cracks are considered:

A. Serious welding defects
B. Normal decorative features
C. Useful shielding layers
D. Types of flux

Answer: A. Serious welding defects

Explanation: Cracks can severely reduce the integrity and service life of a welded component.

Q90. Weld inspection is performed mainly to:

A. Detect defects and verify weld quality
B. Increase fuel consumption
C. Melt the weld again
D. Remove all base metal

Answer: A. Detect defects and verify weld quality

Explanation: Inspection determines whether welds satisfy specified quality requirements.

Q91. Which is a non-destructive testing method?

A. Radiographic testing
B. Tensile testing to fracture
C. Bend testing to failure
D. Machining test

Answer: A. Radiographic testing

Explanation: Radiography can inspect internal discontinuities without destroying the component.

Q92. Ultrasonic testing uses:

A. High-frequency sound waves
B. Electric sparks only
C. Chemical flames
D. Cutting tools

Answer: A. High-frequency sound waves

Explanation: Ultrasonic testing detects internal discontinuities through reflected sound waves.

Q93. Dye penetrant testing is mainly used to detect:

A. Surface-breaking defects
B. Deep internal defects only
C. Material density
D. Melting temperature

Answer: A. Surface-breaking defects

Explanation: Penetrant enters open-to-surface cracks and discontinuities.

Q94. Magnetic particle testing is suitable for detecting surface and near-surface defects in:

A. Ferromagnetic materials
B. All plastics
C. Glass only
D. Wood only

Answer: A. Ferromagnetic materials

Explanation: The method relies on magnetic flux leakage and is therefore suited to ferromagnetic materials.

Q95. A welding helmet primarily protects the:

A. Eyes and face
B. Feet only
C. Welding machine
D. Gas cylinder

Answer: A. Eyes and face

Explanation: The helmet protects against intense arc radiation, sparks and molten metal.

Q96. Welding fumes should be controlled by:

A. Adequate ventilation/fume extraction
B. Closing all ventilation openings
C. Increasing smoke concentration
D. Removing the helmet

Answer: A. Adequate ventilation/fume extraction

Explanation: Proper ventilation reduces exposure to harmful welding fumes and gases.

Q97. One important electrical safety precaution is to:

A. Inspect cables and connections
B. Use damaged cables
C. Touch live conductors
D. Weld in standing water

Answer: A. Inspect cables and connections

Explanation: Damaged insulation or connections can create electric-shock and fire hazards.

Q98. Welding near flammable materials should be:

A. Avoided or controlled using appropriate precautions
B. Encouraged
C. Performed without a fire watch
D. Performed beside fuel containers

Answer: A. Avoided or controlled using appropriate precautions

Explanation: Sparks and hot metal can ignite combustible materials.

Q99. The main purpose of welding symbols on engineering drawings is to:

A. Communicate weld type, location and requirements
B. Show material density
C. Indicate machine weight
D. Specify workshop temperature only

Answer: A. Communicate weld type, location and requirements

Explanation: Standard welding symbols provide manufacturing information to the fabricator.

Q100. Which statement is correct?

A. Welding safety is optional
B. Proper PPE and ventilation are essential
C. Welding helmets are unnecessary
D. Gas cylinders can be handled carelessly

Answer: B. Proper PPE and ventilation are essential

Explanation: Welding involves electrical, thermal, radiation, fumes and fire hazards, so proper safety practices are essential.

CHAPTER 7 — ONE-PAGE EXAM REVISION

Welding Process → Key Feature

SMAW → Flux-coated consumable electrode

TIG/GTAW → Non-consumable tungsten electrode

MIG/GMAW → Continuously fed consumable wire

Gas welding → Combustion flame

Spot welding → Individual weld nuggets

Seam welding → Wheel electrodes

Projection welding → Projections concentrate current

Thermit welding → Exothermic chemical reaction

Friction welding → Solid-state + friction

Ultrasonic welding → High-frequency vibration

Resistance welding →

Flame → Identification

Neutral → Approximately balanced

Oxidizing → Excess oxygen

Carburizing → Excess fuel / reducing character

Defect → Meaning

Porosity → Gas cavities

Slag inclusion → Trapped slag

Undercut → Groove at weld toe

Lack of fusion → Inadequate fusion

Lack of penetration → Inadequate root penetration

Crack → Fracture/discontinuity

Distortion → Dimensional change due to thermal effects

Top of Form

Bottom of Form

CHAPTER 8 — FOUNDRY & CASTING TECHNOLOGY

8.1 Introduction

Casting is one of the oldest and most important manufacturing processes. It is widely used for producing components having complex shapes, internal cavities, large dimensions, and intricate geometries.

Casting is extensively used in:

Automobile industries

Machine-tool industries

Railway equipment

Agricultural machinery

Pumps and valves

Engines

Turbines

Industrial machinery

Aerospace components

Defence equipment

The basic idea is simple:

Melt the metal → Pour into mould → Allow it to solidify → Remove casting

8.2 Definition of Casting

Casting is a manufacturing process in which molten material is poured into a mould cavity of the desired shape and allowed to solidify.

After solidification, the solidified product is removed from the mould and subjected to finishing operations if required.

Key Concept

Casting = Melting + Pouring + Solidification + Removal

8.3 What is a Foundry?

A foundry is a manufacturing facility where metal castings are produced.

Typical foundry operations include:

Pattern making
Mould preparation
Core making
Melting
Pouring
Solidification
Shakeout
Fettling
Inspection

8.4 Basic Steps of Casting

The general sequence is:

Step 1 — Pattern Making

A pattern representing the desired casting is prepared.

Step 2 — Mould Making

The pattern is used to create the mould cavity.

Step 3 — Core Making

Cores are inserted when internal holes or cavities are required.

Step 4 — Melting

The metal is heated above its required melting temperature.

Step 5 — Pouring

Molten metal is poured into the mould cavity.

Step 6 — Solidification

The molten metal cools and becomes solid.

Step 7 — Shakeout

The casting is removed from the mould.

Step 8 — Fettling

Extra material such as gates, runners and risers is removed and the casting is cleaned.

Step 9 — Inspection

The finished casting is inspected for defects and dimensional accuracy.

8.5 Pattern

A pattern is a replica or representation of the desired casting used to form the mould cavity.

The pattern is not necessarily identical in dimensions to the final casting because allowances are generally provided.

8.6 Functions of a Pattern

The main functions of a pattern are:

To create the mould cavity

To reproduce the required shape

To provide necessary allowances

To facilitate moulding

To provide provisions for cores where required

8.7 Pattern Materials

Patterns may be made from:

Wood

Metal

Plastic

Plaster

Wax

Other suitable materials

Wooden Patterns

Advantages:

Cheap

Easy to manufacture

Lightweight

Easy to modify

Disadvantages:

Wear relatively quickly

Absorb moisture

Less durable than metal patterns

8.8 Metal Patterns

Common pattern metals include:

Aluminium alloys

Cast iron

Brass

Bronze

Steel

Metal patterns are generally:

Stronger

More durable

More dimensionally stable

They are suitable for larger production quantities.

8.9 Pattern Allowances

A pattern is generally modified from the exact final casting dimensions because of various manufacturing considerations.

Important pattern allowances include:

Shrinkage allowance
Machining allowance
Draft allowance
Distortion allowance
Rapping/shake allowance

8.10 Shrinkage Allowance

Most metals shrink during solidification and cooling.

Therefore, the pattern is generally made larger than the required final casting dimensions to compensate for shrinkage.

Important

Shrinkage allowance → Positive allowance

8.11 Machining Allowance

Additional material is provided on surfaces that will later be machined.

Purpose

To allow removal of:

Surface irregularities

Oxidized material

Dimensional inaccuracies

Casting skin

Important

Machining allowance → Extra metal for machining

8.12 Draft Allowance

A slight taper is provided on pattern surfaces to facilitate easy removal of the pattern from the mould.

Without adequate draft, the mould cavity may be damaged during pattern withdrawal.

Important

Draft → Easy pattern withdrawal

8.13 Distortion Allowance

Some castings may distort during cooling because of uneven contraction.

In such cases, the pattern can be intentionally distorted in the opposite direction to compensate for expected distortion.

8.14 Shake or Rapping Allowance

When a pattern is loosened by rapping before removal, the mould cavity can become slightly larger.

Therefore, the pattern may require a negative allowance to compensate for this effect.

Important

Rapping allowance → Negative allowance

8.15 Types of Patterns

Important types include:

Single-piece pattern

Split pattern

Match-plate pattern

Cope-and-drag pattern

Loose-piece pattern

Sweep pattern

Skeleton pattern

Segmental pattern

Gated pattern

Follow-board pattern

8.16 Single-Piece Pattern

A single-piece pattern consists of one solid piece.

It is generally suitable for:

Simple shapes

Small production quantities

Simple moulding operations

8.17 Split Pattern

A split pattern is divided into two or more parts.

The division is generally made along the parting line.

Advantage

It facilitates removal of the pattern from the mould.

8.18 Match-Plate Pattern

A match-plate pattern has pattern halves mounted on opposite sides of a plate.

The plate provides the parting surface.

Application

It is particularly useful for:

Mass production of small and medium castings.

8.19 Loose-Piece Pattern

A loose-piece pattern contains detachable portions that allow difficult projections or undercuts to be moulded and the pattern to be removed.

8.20 Sweep Pattern

A sweep pattern consists of a specially shaped board that is rotated around an axis to generate a mould cavity.

It is useful for:

Large axisymmetric castings

Large simple shapes

8.21 Skeleton Pattern

A skeleton pattern consists of a framework representing the shape of the casting.

It is economical for:

Large castings produced in small quantities.

8.22 Mould

A mould is a cavity or form into which molten metal is poured to produce the desired casting.

Moulds may be:

Expendable

Permanent

8.23 Expendable Mould

An expendable mould is normally destroyed during removal of the casting.

Examples:

Sand mould

Plaster mould

Ceramic mould

Main advantage

Complex shapes can be produced relatively easily.

8.24 Permanent Mould

A permanent mould can be reused for producing many castings.

It is generally made from:

Cast iron

Steel

Other heat-resistant materials

Examples:

Permanent mould casting

Die casting

8.25 Moulding Sand

Moulding sand is used to produce the mould cavity in sand casting.

Important properties include:

Refractoriness
Permeability
Strength
Flowability
Plasticity
Adhesiveness
Cohesiveness
Collapsibility

8.26 Refractoriness

Refractoriness is the ability of moulding sand to withstand high temperature without melting or losing its essential properties.

Remember:

Refractoriness → Resistance to high temperature

8.27 Permeability

Permeability is the ability of moulding sand to allow gases and vapours to pass through it.

Why important?

During pouring and solidification, gases are generated. If they cannot escape, they can cause defects such as blowholes and gas porosity.

8.28 Strength

Moulding sand must have sufficient strength to:

Maintain mould shape

Resist erosion

Withstand handling

Resist pressure during pouring

8.29 Cohesiveness

Cohesiveness is the ability of sand particles to stick to one another.

It helps the mould maintain its shape.

8.30 Adhesiveness

Adhesiveness is the ability of moulding sand to stick to the surface of the moulding box or other surfaces.

8.31 Collapsibility

Collapsibility is the ability of moulding sand to break down or yield after solidification of the casting.

It helps prevent excessive resistance to contraction and reduces the risk of hot tearing.

8.32 Green Sand

Green sand is a commonly used moulding sand containing:

Sand

Clay/binder

Water

Other additives as required

The term green refers to the fact that the mould contains moisture and is generally used in the moist condition.

8.33 Dry Sand Mould

A dry sand mould is dried or baked before pouring.

Compared with green sand moulds, dry sand moulds generally have:

Higher strength

Better dimensional stability

Higher cost

8.34 Core

A core is used to produce internal cavities or holes in a casting.

Example

If a casting requires an internal passage, a core can be placed inside the mould cavity before pouring.

Key Concept

Core → Internal cavity

8.35 Core Print

A core print is a projection or recess provided on the pattern/moulding arrangement to locate and support the core.

8.36 Gating System

The gating system is the passage system through which molten metal flows from the pouring basin to the mould cavity.

Typical components include:

Pouring basin

Sprue

Runner

Gate

Riser

8.37 Pouring Basin

The pouring basin receives molten metal from the ladle and directs it toward the sprue.

It helps provide controlled entry of molten metal.

8.38 Sprue

The sprue is the vertical passage through which molten metal flows downward from the pouring basin.

In many conventional systems, it also helps provide a smooth flow path and may be tapered to reduce aspiration.

8.39 Runner

The runner is a horizontal or approximately horizontal passage that carries molten metal from the sprue toward the gates.

8.40 Gate

A gate is the passage through which molten metal enters the mould cavity from the runner.

8.41 Riser

A riser, also called a feeder, is a reservoir of molten metal that supplies additional metal to the casting during solidification.

Main function

Compensate for solidification shrinkage.

8.42 Casting Defects

Important casting defects include:

Blowholes

Porosity

Shrinkage cavity

Misrun

Cold shut

Hot tears

Sand inclusion

Metal penetration

Mould shift

Core shift

Fins

Scabs

8.43 Misrun

A misrun occurs when molten metal fails to completely fill the mould cavity before solidifying.

Possible causes:

Low pouring temperature

Insufficient fluidity

Slow pouring

Thin sections

Poor gating design

8.44 Cold Shut

A cold shut occurs when two streams of molten metal meet but fail to fuse properly.

It appears as a seam or line on the casting.

8.45 Shrinkage Cavity

Shrinkage cavity results from insufficient feeding of molten metal during solidification.

A properly designed riser helps reduce this defect.

8.46 Blowholes

Blowholes are relatively large cavities caused by gases trapped within the casting.

Possible causes include:

Poor mould permeability

Excess moisture

Improper venting

8.47 Hot Tears

Hot tears are cracks formed during the final stages of solidification when the metal is unable to contract freely.

Poor collapsibility of the mould/core can contribute to hot tearing.

8.48 Fettling

Fettling includes cleaning and finishing operations performed after casting removal.

Typical operations include:

Removing gates

Removing risers

Removing fins

Cleaning sand

Grinding rough surfaces

8.49 Cupola Furnace

The cupola furnace is traditionally used for melting:

Cast iron

It is a vertical shaft furnace used extensively in foundries.

8.50 Important Casting Revision

Term	Key Point
Pattern	Forms mould cavity
Shrinkage allowance	Compensates for shrinkage
Machining allowance	Extra metal for machining
Draft allowance	Easy pattern withdrawal
Rapping allowance	Usually negative
Core	Internal cavity
Core print	Supports/locates core
Refractoriness	Withstands high temperature
Permeability	Allows gases to escape
Collapsibility	Allows mould to yield after solidification
Sprue	Vertical passage
Runner	Carries metal toward gates
Gate	Entry into cavity
Riser	Feeds metal during solidification
Misrun	Incomplete filling
Cold shut	Streams fail to fuse
Blowhole	Gas cavity
Hot tear	Crack during solidification
Fettling	Cleaning/finishing
Cupola	Traditionally melts cast iron

Q1. Casting is a process in which molten metal is:

A. Rolled into sheets
B. Poured into a mould and solidified
C. Forged between dies
D. Cut by a tool

Answer: B. Poured into a mould and solidified

Explanation: Casting produces a component by pouring molten material into a mould cavity and allowing it to solidify.

Q2. A foundry is primarily concerned with:

A. Casting production
B. Thread cutting
C. Gear hobbing only
D. Sheet rolling only

Answer: A. Casting production

Explanation: A foundry is a facility where metal melting, moulding, pouring and casting operations are performed.

Q3. The replica used to form the mould cavity is called:

A. Core
B. Pattern
C. Riser
D. Runner

Answer: B. Pattern

Explanation: The pattern represents the shape of the desired casting and is used to form the mould cavity.

Q4. Which allowance compensates for metal contraction during cooling?

A. Draft allowance
B. Shrinkage allowance
C. Machining allowance
D. Rapping allowance

Answer: B. Shrinkage allowance

Explanation: The pattern is enlarged to compensate for contraction of the metal during solidification and cooling.

Q5. Draft allowance is provided mainly to:

A. Facilitate pattern removal
B. Increase metal hardness
C. Reduce melting temperature
D. Increase mould moisture

Answer: A. Facilitate pattern removal

Explanation: A slight taper allows the pattern to be withdrawn without damaging the mould cavity.

Q6. Machining allowance provides:

A. Extra material for subsequent machining
B. Extra gas for the mould
C. Extra water for sand
D. Extra core support

Answer: A. Extra material for subsequent machining

Explanation: Additional metal is intentionally provided on surfaces that will be machined after casting.

Q7. Rapping allowance is generally:

A. Positive
B. Negative
C. Zero in every case
D. Equal to machining allowance

Answer: B. Negative

Explanation: Rapping can enlarge the mould cavity, so a negative allowance can compensate for the effect.

Q8. A split pattern is generally divided along the:

A. Parting line
B. Sprue
C. Runner
D. Riser

Answer: A. Parting line

Explanation: The split permits easier pattern withdrawal from the mould.

Q9. Match-plate patterns are especially suitable for:

A. Mass production
B. One-off giant castings only
C. Hand forging
D. Welding

Answer: A. Mass production

Explanation: Match-plate patterns facilitate rapid and consistent mould production.

Q10. A skeleton pattern is generally economical for:

A. Large castings in small quantities
B. Mass-produced tiny castings
C. Wire drawing
D. Sheet rolling

Answer: A. Large castings in small quantities

Explanation: Only a framework is provided, reducing pattern material and manufacturing cost.

Q11. A sweep pattern is useful for producing:

A. Large axisymmetric moulds
B. Small gears only
C. Bolts only
D. Welding electrodes

Answer: A. Large axisymmetric moulds

Explanation: A shaped board is swept around an axis to generate the mould surface.

Q12. A core is primarily used to produce:

A. External surface finish
B. Internal cavity
C. Pattern draft
D. Riser height

Answer: B. Internal cavity

Explanation: Cores occupy space in the mould and create internal holes or passages.

Q13. Which property of moulding sand allows gases to escape?

A. Permeability
B. Hardness
C. Density
D. Elasticity

Answer: A. Permeability

Explanation: Permeability allows gases generated during pouring and solidification to pass through the mould.

Q14. Refractoriness of moulding sand refers to its ability to:

A. Resist high temperature
B. Absorb oil
C. Increase casting weight
D. Melt rapidly

Answer: A. Resist high temperature

Explanation: Refractory sand must withstand molten-metal temperatures without melting or deteriorating excessively.

Q15. Collapsibility of moulding sand is important because it:

A. Allows the mould to yield during casting contraction
B. Increases melting temperature
C. Prevents all gas escape
D. Makes the metal harder

Answer: A. Allows the mould to yield during casting contraction

Explanation: Good collapsibility reduces resistance to contraction and helps reduce hot tearing.

Q16. Green sand normally contains:

A. Sand, clay/binder and water
B. Only pure metal
C. Only cement
D. Only oil

Answer: A. Sand, clay/binder and water

Explanation: Green sand is commonly a moist sand mixture containing clay/binder and other additives.

Q17. The vertical passage in a conventional gating system is called:

A. Runner
B. Sprue
C. Gate
D. Riser

Answer: B. Sprue

Explanation: The sprue carries molten metal downward from the pouring basin.

Q18. The horizontal passage carrying metal from sprue to gate is called:

A. Runner
B. Core
C. Riser
D. Pattern

Answer: A. Runner

Explanation: The runner distributes molten metal from the sprue toward one or more gates.

Q19. The passage through which molten metal enters the mould cavity is the:

A. Gate
B. Core print
C. Pattern
D. Vent only

Answer: A. Gate

Explanation: The gate connects the runner to the mould cavity.

Q20. The main function of a riser is to:

A. Feed molten metal during solidification
B. Create the pattern
C. Remove the core
D. Increase permeability

Answer: A. Feed molten metal during solidification

Explanation: The riser acts as a reservoir and compensates for solidification shrinkage.

Q21. A casting defect caused by incomplete filling of the mould is:

A. Misrun
B. Blowhole
C. Hot tear
D. Scab

Answer: A. Misrun

Explanation: A misrun occurs when metal solidifies before completely filling the mould cavity.

Q22. A defect caused when two streams of molten metal fail to fuse is:

A. Cold shut
B. Shrinkage cavity
C. Blowhole
D. Sand inclusion

Answer: A. Cold shut

Explanation: A cold shut appears where separate streams meet but do not properly fuse.

Q23. A gas cavity in a casting is called:

A. Blowhole
B. Cold shut
C. Misrun
D. Hot tear

Answer: A. Blowhole

Explanation: Blowholes result from trapped gases in the casting.

Q24. A shrinkage cavity is mainly associated with:

A. Insufficient feeding during solidification
B. Excessive pattern draft only
C. Excessive mould permeability only
D. Pattern colour

Answer: A. Insufficient feeding during solidification

Explanation: As metal contracts during solidification, a sufficient supply of molten metal is needed to prevent internal voids.

Q25. Cupola furnaces are traditionally used mainly for melting:

A. Cast iron
B. Aluminium only
C. Copper only
D. Plastic

Answer: A. Cast iron

Explanation: The cupola is a vertical shaft furnace traditionally used extensively for melting cast iron in foundries.

MCQ 26–40 — Moulding Sand & Patterns

Q26. The property of moulding sand that enables it to withstand molten-metal temperature is:

A. Permeability
B. Refractoriness
C. Plasticity
D. Adhesiveness

Answer: B. Refractoriness

Explanation: Refractoriness is the ability of moulding material to withstand high temperatures without fusing or deteriorating excessively.

Q27. Which property of moulding sand is essential for the escape of gases?

A. Permeability
B. Toughness
C. Hardness
D. Elasticity

Answer: A. Permeability

Explanation: Gases generated during pouring and solidification must escape through the mould.

Q28. The ability of moulding sand to retain its shape during handling is mainly related to:

A. Strength
B. Melting point
C. Density
D. Thermal conductivity

Answer: A. Strength

Explanation: Adequate mould strength prevents the cavity from collapsing or eroding during mould handling and pouring.

Q29. Which property allows moulding sand to stick to another surface?

A. Adhesiveness
B. Permeability
C. Refractoriness
D. Collapsibility

Answer: A. Adhesiveness

Explanation: Adhesiveness is the tendency of moulding sand to adhere to the surface of the moulding box or other materials.

Q30. The ability of sand particles to stick to one another is called:

A. Cohesiveness
B. Adhesiveness
C. Permeability
D. Fluidity

Answer: A. Cohesiveness

Explanation: Cohesiveness helps individual sand grains bind together and maintain the mould shape.

Q31. Which property is desirable to allow easy breakdown of the mould after casting?

A. Collapsibility
B. Excessive hardness
C. Low refractoriness
D. Low strength

Answer: A. Collapsibility

Explanation: The mould should collapse sufficiently after solidification to allow casting removal and accommodate contraction.

Q32. Excessive moisture in moulding sand may lead to:

A. Gas-related defects
B. Increased metal strength in every case
C. Zero porosity
D. Elimination of shrinkage

Answer: A. Gas-related defects

Explanation: Excess moisture can generate steam and gases during pouring, potentially causing blowholes and other defects.

Q33. Which type of sand mould is used in a moist condition?

A. Green sand mould
B. Dry sand mould
C. Ceramic mould
D. Permanent mould

Answer: A. Green sand mould

Explanation: Green sand contains moisture and is generally used without complete drying.

Q34. The major binder traditionally used in green sand is:

A. Clay
B. Copper
C. Aluminium
D. Steel

Answer: A. Clay

Explanation: Clay provides bonding between sand grains and helps maintain mould strength.

Q35. The primary purpose of a pattern is to:

A. Produce the mould cavity
B. Melt the metal
C. Feed the casting
D. Remove slag

Answer: A. Produce the mould cavity

Explanation: The pattern represents the casting geometry and is used to create the cavity into which molten metal is poured.

Q36. A pattern is generally made larger than the required casting because of:

A. Allowances
B. Welding defects
C. Cutting forces
D. Rolling pressure

Answer: A. Allowances

Explanation: Shrinkage, machining and other allowances are incorporated into the pattern as required.

Q37. Which allowance is provided to facilitate pattern withdrawal?

A. Draft allowance
B. Shrinkage allowance
C. Machining allowance
D. Rapping allowance

Answer: A. Draft allowance

Explanation: Draft provides taper on vertical pattern surfaces, making removal easier.

Q38. The amount of draft required depends on:

A. Pattern material and moulding method
B. Colour of the pattern
C. Foundry floor area only
D. Metal electrical conductivity only

Answer: A. Pattern material and moulding method

Explanation: Pattern surface condition, moulding method, depth and material influence the required draft.

Q39. Machining allowance is generally greater for:

A. Surfaces requiring extensive machining
B. Surfaces requiring no finishing
C. Wax patterns only
D. Core prints only

Answer: A. Surfaces requiring extensive machining

Explanation: More material must be provided where greater metal removal will be required during machining.

Q40. Which pattern is divided into two parts?

A. Split pattern
B. Sweep pattern
C. Skeleton pattern
D. Single-piece pattern

Answer: A. Split pattern

Explanation: Split patterns consist of separate portions, generally corresponding to the two sides of the parting line.

MCQ 41–55 — Pattern Types & Cores

Q41. A pattern consisting of two halves mounted on opposite sides of a plate is:

A. Match-plate pattern
B. Skeleton pattern
C. Sweep pattern
D. Segmental pattern

Answer: A. Match-plate pattern

Explanation: Match-plate patterns have the pattern halves attached to a common plate and are useful for production moulding.

Q42. A skeleton pattern is particularly suitable for:

A. Large castings in small quantities
B. High-volume tiny castings
C. Wire production
D. Sheet rolling

Answer: A. Large castings in small quantities

Explanation: A framework is used instead of a solid pattern, reducing pattern cost for large, low-volume castings.

Q43. A sweep pattern generates a mould surface by:

A. Rotating a shaped board around an axis
B. Welding two plates
C. Rolling a metal sheet
D. Hammering the mould

Answer: A. Rotating a shaped board around an axis

Explanation: The sweep board produces the required mould profile as it is rotated.

Q44. A loose-piece pattern is useful when:

A. The pattern contains difficult projections or undercuts
B. No mould is required
C. Only flat surfaces are involved
D. No pattern withdrawal is needed

Answer: A. The pattern contains difficult projections or undercuts

Explanation: Detachable portions allow the pattern to be removed without damaging the mould.

Q45. A core is used primarily to produce:

A. Internal cavities
B. External dimensions
C. Pattern colour
D. Riser volume

Answer: A. Internal cavities

Explanation: Cores occupy space within the mould and create internal holes, passages and cavities.

Q46. A core is generally made from:

A. Core sand
B. Pure molten metal
C. Cutting fluid
D. Lubricating oil

Answer: A. Core sand

Explanation: Specially prepared core sand is used to produce cores with adequate strength and collapsibility.

Q47. The core is supported in the mould by:

A. Core prints
B. Runners only
C. Risers only
D. Gates only

Answer: A. Core prints

Explanation: Core prints provide locating and supporting surfaces for the core.

Q48. Core prints are generally provided on:

A. The pattern
B. The ladle
C. The furnace wall
D. The runner only

Answer: A. The pattern

Explanation: Core prints are incorporated into the pattern to create supporting recesses in the mould.

Q49. Which casting component creates an internal cylindrical hole?

A. Core
B. Riser
C. Runner
D. Sprue

Answer: A. Core

Explanation: A cylindrical core placed in the mould creates the corresponding internal hole.

Q50. The main requirement of a core is:

A. Adequate strength and collapsibility
B. Complete non-porosity under all conditions
C. Maximum hardness only
D. Zero gas permeability

Answer: A. Adequate strength and collapsibility

Explanation: The core must survive handling and pouring but should also collapse sufficiently after solidification.

Q51. Core prints are primarily used to:

A. Locate the core
B. Increase metal temperature
C. Reduce melting time
D. Remove slag

Answer: A. Locate the core

Explanation: They establish the correct position of the core inside the mould.

Q52. Which component is NOT normally part of a conventional core?

A. Core sand
B. Binder
C. Reinforcement where required
D. Molten casting metal

Answer: D. Molten casting metal

Explanation: A core is made before pouring and consists of prepared core material rather than molten casting metal.

Q53. A core should have sufficient permeability because:

A. Gases must escape
B. It must prevent all gas flow
C. It must increase casting shrinkage
D. It must act as a riser

Answer: A. Gases must escape

Explanation: Gas generated within or around the core must be vented to prevent casting defects.

Q54. Excessively strong cores may cause:

A. Difficulty in collapse after casting solidification
B. Zero casting weight
C. Increased fluidity
D. Reduced metal temperature

Answer: A. Difficulty in collapse after casting solidification

Explanation: Poor core collapsibility can restrict contraction and contribute to hot tears or difficulties during shakeout.

Q55. Which component creates an opening but does NOT normally form part of the final metal casting?

A. Core
B. Casting wall
C. Metal insert
D. Permanent feature

Answer: A. Core

Explanation: The core is removed after casting, leaving the cavity or passage.

MCQ 56–70 — Gating System & Riser

Q56. The complete passage system carrying molten metal to the mould cavity is called:

A. Gating system
B. Core system
C. Pattern system
D. Cooling system

Answer: A. Gating system

Explanation: The gating system controls the delivery of molten metal into the mould cavity.

Q57. The first receiving portion of a conventional gating system is:

A. Pouring basin
B. Riser
C. Core
D. Gate

Answer: A. Pouring basin

Explanation: The pouring basin receives molten metal from the ladle and directs it into the sprue.

Q58. The sprue is generally:

A. Vertical
B. Horizontal only
C. Circular only
D. Inclined at 90° only

Answer: A. Vertical

Explanation: In conventional gravity casting systems, the sprue is a vertical passage.

Q59. The runner is used to:

A. Distribute molten metal toward gates
B. Create internal holes
C. Remove the pattern
D. Support the core

Answer: A. Distribute molten metal toward gates

Explanation: The runner connects the sprue to one or more gates.

Q60. The gate connects the:

A. Runner and mould cavity
B. Core and riser
C. Pattern and furnace
D. Ladle and furnace

Answer: A. Runner and mould cavity

Explanation: Molten metal enters the mould cavity through the gate.

Q61. The principal function of a riser is to:

A. Supply molten metal during solidification
B. Create the mould cavity
C. Remove gases only
D. Hold the pattern

Answer: A. Supply molten metal during solidification

Explanation: The riser compensates for shrinkage as the casting solidifies.

Q62. A riser is also called a:

A. Feeder
B. Core
C. Pattern
D. Sprue

Answer: A. Feeder

Explanation: A riser feeds additional molten metal to the casting.

Q63. The riser should generally remain molten:

A. Longer than the casting section it feeds
B. Shorter than the casting in every case
C. Before pouring begins
D. Only after complete solidification

Answer: A. Longer than the casting section it feeds

Explanation: The riser must remain liquid sufficiently long to supply metal during solidification.

Q64. Which component is designed primarily to reduce shrinkage defects?

A. Riser
B. Pattern
C. Core print
D. Moulding box

Answer: A. Riser

Explanation: A properly designed feeder/riser provides molten metal to compensate for solidification contraction.

Q65. A properly designed gating system should:

A. Deliver metal smoothly and minimize turbulence
B. Maximize air entrapment
C. Prevent all metal flow
D. Increase slag formation deliberately

Answer: A. Deliver metal smoothly and minimize turbulence

Explanation: Controlled flow reduces mould erosion, air entrainment and other defects.

Q66. Excessive turbulence during pouring can increase:

A. Oxidation and air entrapment
B. Dimensional accuracy
C. Metal purity in every case
D. Core strength

Answer: A. Oxidation and air entrapment

Explanation: Turbulent flow can entrain air and oxide films and may erode mould surfaces.

Q67. A sprue may be tapered to:

A. Reduce aspiration and improve flow
B. Increase air entry
C. Stop metal flow
D. Increase casting porosity

Answer: A. Reduce aspiration and improve flow

Explanation: A properly tapered sprue helps maintain a full-flowing stream and reduces air aspiration.

Q68. The molten metal enters the mould cavity through the:

A. Gate
B. Riser only
C. Core print
D. Pattern

Answer: A. Gate

Explanation: The gate is the final passage between the runner and mould cavity.

Q69. Which sequence is correct for a conventional gravity gating system?

A. Pouring basin → Sprue → Runner → Gate → Cavity
B. Gate → Runner → Sprue → Basin → Cavity
C. Cavity → Gate → Basin → Sprue
D. Riser → Core → Runner → Basin

Answer: A. Pouring basin → Sprue → Runner → Gate → Cavity

Explanation: This represents the normal direction of molten-metal flow.

Q70. A riser is normally located:

A. At a suitable location connected to the casting
B. Inside the furnace only
C. Inside the ladle only
D. On the pattern storage rack

Answer: A. At a suitable location connected to the casting

Explanation: Its location is selected to feed regions most susceptible to shrinkage.

MCQ 71–85 — Furnaces & Casting Processes

Q71. A cupola furnace is primarily used for melting:

A. Cast iron
B. Wood
C. Plastic
D. Glass only

Answer: A. Cast iron

Explanation: Cupola furnaces have traditionally been widely used for melting cast iron in foundries.

Q72. A cupola is a:

A. Vertical shaft furnace
B. Horizontal rolling machine
C. Forging press
D. Welding machine

Answer: A. Vertical shaft furnace

Explanation: The cupola has a vertical cylindrical shaft through which charge materials descend.

Q73. Which fuel is traditionally used in a cupola furnace?

A. Coke
B. Wood only
C. Petrol only
D. Water

Answer: A. Coke

Explanation: Coke acts as a fuel and provides heat for melting in traditional cupola operation.

Q74. The charge in a cupola may include:

A. Metal, coke and flux
B. Only sand
C. Only water
D. Only clay

Answer: A. Metal, coke and flux

Explanation: The metallic charge, fuel and flux are important components of cupola operation.

Q75. The purpose of flux in a melting furnace is generally to:

A. Help form and remove slag
B. Increase pattern dimensions
C. Produce cores
D. Measure temperature only

Answer: A. Help form and remove slag

Explanation: Flux combines with impurities to form slag that can be separated from the molten metal.

Q76. Which casting process uses a reusable metal mould?

A. Permanent mould casting
B. Green sand casting only
C. Shell sand casting only
D. Plaster mould casting only

Answer: A. Permanent mould casting

Explanation: Permanent moulds are designed for repeated use.

Q77. Die casting generally uses:

A. A permanent metal die
B. A disposable wooden pattern only
C. A sand core as the entire mould
D. A paper mould

Answer: A. A permanent metal die

Explanation: Die casting uses reusable dies and is suited to high-volume production.

Q78. Die casting is particularly suitable for:

A. High-volume production of relatively small complex parts
B. One-off huge sand castings
C. Hand forging
D. Wood products

Answer: A. High-volume production of relatively small complex parts

Explanation: High production rates and good dimensional consistency are major advantages of die casting.

Q79. In pressure die casting, molten metal is introduced into the die:

A. Under pressure
B. Only by gravity
C. By hand hammering
D. Through a sand shovel

Answer: A. Under pressure

Explanation: Pressure assists rapid filling of the permanent die cavity.

Q80. Investment casting is also commonly called:

A. Lost-wax casting
B. Sand forging
C. Cold rolling
D. Drop forging

Answer: A. Lost-wax casting

Explanation: A wax pattern is surrounded by investment material and later removed before metal is cast.

Q81. Investment casting is suitable for producing:

A. Complex and accurate components
B. Only very simple plates
C. Only wooden components
D. Only rolled sheets

Answer: A. Complex and accurate components

Explanation: The process can reproduce intricate geometries and fine details.

Q82. In investment casting, the wax pattern is:

A. Removed before metal casting
B. Retained as the final metal component
C. Used as the riser
D. Used as the furnace lining

Answer: A. Removed before metal casting

Explanation: The wax is melted or otherwise removed to create the cavity into which metal is poured.

Q83. Centrifugal casting uses:

A. Centrifugal force
B. Only compressed air
C. Only chemical reaction
D. Manual hammering

Answer: A. Centrifugal force

Explanation: Rotation forces molten metal against the mould wall.

Q84. Centrifugal casting is particularly suitable for:

A. Hollow cylindrical components
B. Flat wooden plates
C. Small bolts only
D. Welding rods

Answer: A. Hollow cylindrical components

Explanation: Pipes, tubes and similar rotationally symmetric hollow components are common applications.

Q85. Shell moulding uses:

A. A thin shell of resin-bonded sand
B. Only molten metal
C. A wooden shell
D. A rubber tube

Answer: A. A thin shell of resin-bonded sand

Explanation: A heated pattern is coated with resin-bonded sand to form a relatively thin mould shell.

MCQ 86–100 — Casting Defects, Finishing & Inspection

Q86. A casting that does not completely fill the mould cavity has:

A. Misrun
B. Cold shut
C. Hot tear
D. Scab

Answer: A. Misrun

Explanation: A misrun results from premature solidification before complete cavity filling.

Q87. A cold shut is associated with:

A. Failure of two molten streams to fuse
B. Excessive riser feeding
C. Pattern removal
D. Complete mould filling

Answer: A. Failure of two molten streams to fuse

Explanation: Separate streams meet but do not form a continuous homogeneous metal connection.

Q88. Shrinkage cavities are most directly related to:

A. Solidification contraction
B. Pattern colour
C. Sand grain colour
D. Tool geometry

Answer: A. Solidification contraction

Explanation: Metal contracts during solidification, and inadequate feeding can leave internal cavities.

Q89. A blowhole is mainly caused by:

A. Trapped gas
B. Excessive machining
C. Pattern draft
D. Rapping

Answer: A. Trapped gas

Explanation: Gases that cannot escape can form cavities within the casting.

Q90. Sand inclusion means:

A. Sand particles become embedded in the casting
B. Gas becomes trapped
C. Metal fails to melt
D. Pattern expands

Answer: A. Sand particles become embedded in the casting

Explanation: Mould erosion or poor mould strength can cause sand to become incorporated into the metal.

Q91. Hot tears occur mainly because of:

A. Restrained contraction during solidification
B. Excessive machining allowance only
C. Pattern colour
D. High permeability alone

Answer: A. Restrained contraction during solidification

Explanation: If the casting cannot contract freely during late solidification, tensile stresses can cause hot tearing.

Q92. A mould shift can result in:

A. Dimensional mismatch between casting halves
B. Better dimensional accuracy
C. Increased melting point
D. Zero defects

Answer: A. Dimensional mismatch between casting halves

Explanation: Improper alignment of cope and drag can produce a mismatch at the parting line.

Q93. Core shift may cause:

A. Incorrect position of internal cavities
B. Increased metal purity
C. Reduced casting weight in every case
D. Improved dimensional accuracy

Answer: A. Incorrect position of internal cavities

Explanation: If the core moves from its intended position, internal holes or passages will be misplaced.

Q94. Fins on castings are generally caused by:

A. Metal entering unwanted gaps at mould joints
B. Low gas pressure only
C. Insufficient pattern size
D. Core permeability

Answer: A. Metal entering unwanted gaps at mould joints

Explanation: Thin projections can form when molten metal penetrates cracks or gaps in the mould.

Q95. Fettling is carried out:

A. After casting removal
B. Before pattern manufacture only
C. Before melting
D. Before mould preparation

Answer: A. After casting removal

Explanation: Fettling includes removal of gates, risers, fins, adhering sand and other unwanted material.

Q96. One operation in fettling is:

A. Removal of gates and risers
B. Pattern design
C. Core printing
D. Furnace charging only

Answer: A. Removal of gates and risers

Explanation: Gates and risers are unwanted portions attached to the casting and are removed during finishing.

Q97. Radiographic testing of castings is used mainly to detect:

A. Internal defects
B. Pattern colour
C. Surface roughness only
D. Casting weight only

Answer: A. Internal defects

Explanation: X-rays or gamma rays can reveal internal discontinuities such as porosity and inclusions.

Q98. Dye penetrant inspection is particularly useful for:

A. Surface-breaking cracks
B. Deep internal shrinkage only
C. Melting-point measurement
D. Chemical composition measurement

Answer: A. Surface-breaking cracks

Explanation: Penetrant enters open surface discontinuities and makes them visible during inspection.

Q99. Dimensional inspection of a casting is performed to:

A. Verify required dimensions and tolerances
B. Increase metal temperature
C. Remove all internal cavities
D. Change the chemical composition

Answer: A. Verify required dimensions and tolerances

Explanation: Measuring instruments are used to determine whether the casting conforms to its specified dimensions.

Q100. Which sequence correctly represents the basic casting process?

A. Pattern → Mould → Melting → Pouring → Solidification → Shakeout
B. Melting → Pattern → Welding → Rolling
C. Welding → Pattern → Forging → Casting
D. Rolling → Melting → Pattern → Grinding

Answer: A. Pattern → Mould → Melting → Pouring → Solidification → Shakeout

Explanation: This is the basic sequence from pattern preparation through removal of the solidified casting.

CHAPTER 8 — QUICK REVISION

Pattern

Pattern → Produces mould cavity

Allowances

Shrinkage → Compensates metal contraction

Machining → Extra material for machining

Draft → Easy pattern withdrawal

Distortion → Compensates expected distortion

Rapping → Generally negative

Moulding Sand

Refractoriness → Withstands heat

Permeability → Allows gas escape

Strength → Maintains mould shape

Cohesiveness → Sand grains stick together

Adhesiveness → Sand sticks to mould box

Collapsibility → Breaks down after solidification

Gating System

Pouring Basin → Sprue → Runner → Gate → Mould Cavity

Feeding

Riser → Feeds molten metal during solidification

Core

Core → Internal cavity

Important Processes

Sand casting → Expendable mould

Die casting → Permanent die + pressure

Investment casting → Lost-wax process

Centrifugal casting → Rotation/centrifugal force

Shell moulding → Resin-bonded sand shell

Cupola → Traditionally used for cast iron

Important Defects

Misrun → Incomplete filling

Cold shut → Streams fail to fuse

Blowhole → Gas cavity

Shrinkage cavity → Inadequate feeding

Hot tear → Restrained contraction

Sand inclusion → Sand trapped in casting

Mould shift → Misalignment of mould halves

Core shift → Incorrect internal cavity position

CHAPTER 9 — FORGING TECHNOLOGY

9.1 Introduction

Forging is one of the oldest metal-forming processes and is extremely important in manufacturing engineering. It is widely used when components require high strength, toughness, reliability and directional grain flow.

Forging is commonly used to manufacture:

Crankshafts

Connecting rods

Gear blanks

Spanners

Bolts

Shafts

Axles

Hooks

Wrenches

Aircraft components

Automobile components

Hand tools

9.2 Definition of Forging

Forging is a manufacturing process in which a metal workpiece is plastically deformed into the desired shape by the application of compressive forces.

The compressive force may be applied using:

Hammer

Press

Die

Mechanical equipment

Hydraulic equipment

Key Concept

Forging = Plastic deformation + Compressive force

9.3 Principle of Forging

The basic principle of forging is to bring the workpiece into a condition where it can undergo plastic deformation and then apply sufficient compressive force to obtain the desired shape.

Depending on the process, the metal may be heated before deformation.

9.4 Why Is Metal Heated Before Forging?

In hot forging, the workpiece is heated to an appropriate temperature to:

Reduce flow stress

Increase ductility

Reduce required forging force

Permit greater deformation

Refine the grain structure under suitable conditions

However, overheating must be avoided because it can cause:

Excessive grain growth

Oxidation

Burning

Loss of material properties

9.5 Types of Forging Based on Temperature

Forging can broadly be classified as:

Hot forging
Warm forging
Cold forging

9.6 Hot Forging

Hot forging is carried out at a temperature sufficiently high to allow substantial plastic deformation with relatively low resistance.

Advantages

Lower forging force

Large deformation possible

Better workability

Suitable for large components

Disadvantages

Oxidation/scale formation

Lower dimensional accuracy than cold forging

Surface finish may be poorer

Heating cost

9.7 Cold Forging

Cold forging is performed at or near room temperature.

Advantages

Good dimensional accuracy

Good surface finish

No heating scale

Improved strength due to work hardening

Disadvantages

High deformation force

Limited deformation

Greater possibility of cracking in less ductile materials

Tool loads are high

9.8 Warm Forging

Warm forging is performed between conventional cold-forging and hot-forging temperature ranges.

It attempts to obtain a balance between:

Lower forming force

Better dimensional accuracy

Reduced oxidation

Improved material formability

9.9 Classification Based on Equipment

Forging can also be classified according to the equipment used:

1. Hammer Forging

The deformation is produced mainly by impact.

2. Press Forging

The deformation is produced mainly by gradual application of compressive force.

9.10 Hammer Forging

In hammer forging, the workpiece is deformed by repeated blows.

Examples of equipment include:

Drop hammer

Power hammer

Main characteristic

Impact loading

9.11 Press Forging

In press forging, deformation is produced by applying pressure gradually.

Presses may be:

Mechanical

Hydraulic

Main characteristic

Gradual compressive loading

9.12 Hammer vs Press Forging

Hammer Forging	Press Forging
Impact load	Gradual load
Repeated blows	Continuous pressure
Deformation may be concentrated near surface	Deformation can penetrate deeper
High strain rate	Lower strain rate
Suitable for many die-forging operations	Suitable for large/deep deformation

9.13 Open-Die Forging

In open-die forging, the workpiece is compressed between dies that do not completely enclose the material.

The metal is allowed to flow laterally.

Applications

Large shafts

Large rings

Heavy forgings

Large blocks

9.14 Closed-Die Forging

In closed-die forging, the workpiece is placed within shaped die cavities.

The dies approach each other and force the material to flow into the cavity.

Advantages

Complex shapes possible

Good dimensional accuracy

High production rate

Good mechanical properties

9.15 Impression-Die Forging

In impression-die forging, the dies contain impressions corresponding to the desired component geometry.

The material flows into these impressions under compressive force.

Excess material may form flash around the die parting line.

9.16 Flash

Flash is the thin excess metal that flows out between the die faces during impression-die forging.

Flash is subsequently removed by a trimming operation.

Important

Flash → Excess metal at die parting line

9.17 Flashless Forging

In flashless forging, the amount of material is carefully controlled so that the workpiece fills the die cavity without producing significant flash.

Advantages

Better material utilization

Reduced waste

Requirement

Accurate control of billet volume is important.

9.18 Upset Forging

Upset forging increases the cross-sectional area of a portion of the workpiece by reducing its length.

Example

Production of:

Bolt heads

Rivet heads

Fastener heads

Key Concept

Upsetting → Length decreases, cross-sectional area increases

9.19 Drawing Out

Drawing out is a forging operation in which:

Length increases and cross-sectional area decreases.

It is essentially the opposite of upsetting.

Key Concept

Drawing out → Length ↑, area ↓

9.20 Fullering

Fullering is used to distribute metal along the length of a workpiece.

Fullers have rounded or specially shaped surfaces.

It is often used before drawing-out operations.

9.21 Edging

Edging is used to gather or redistribute material at a particular location.

It is commonly used in die forging to prepare the required amount of material for subsequent impressions.

9.22 Bending

Bending is a forging operation in which the workpiece is given a curved or angular shape.

It is commonly used in producing:

Hooks

Links

Brackets

Certain hand tools

9.23 Punching

Punching is the operation of producing a hole by forcing a punch through a hot workpiece.

The removed material may form a slug.

9.24 Piercing

Piercing is related to producing a hole or cavity by forcing a tool into the workpiece.

The exact terminology can vary with the forging process and application.

9.25 Trimming

Trimming removes unwanted flash from a forged component.

Sequence

Forging → Flash formation → Trimming

9.26 Swaging

Swaging is a forging operation used to reduce or modify the cross-section of a workpiece by dies.

It can be performed using:

Rotary swaging

Die-based equipment

9.27 Heading

Heading is a form of upsetting used extensively in fastener manufacturing.

It is used for producing:

Bolt heads

Screw heads

Rivet heads

9.28 Coining

Coining is a precision forging operation in which very high pressure is used to produce fine surface details and accurate dimensions.

It is commonly associated with:

Coins

Medallions

Precision components

Important

Coining → High-pressure precision forging

9.29 Sizing

Sizing is a finishing forging operation used to obtain:

Better dimensional accuracy

Improved surface conformity

Only a relatively small amount of deformation is generally involved.

9.30 Roll Forging

In roll forging, the workpiece passes between rotating rolls containing shaped grooves.

The rolls progressively deform the workpiece.

Applications

Tapered components

Shafts

Axle components

Blanks

9.31 Rotary Forging

Rotary forging uses a die that applies deformation progressively over the workpiece rather than deforming the entire area simultaneously.

It can reduce required force compared with some conventional forging arrangements.

9.32 Forging Dies

Forging dies provide the surfaces against which the workpiece is deformed.

They can broadly be:

Open dies

Impression dies

Closed dies

9.33 Die Materials

Forging dies require materials having:

High strength

High toughness

Good wear resistance

Resistance to thermal fatigue

Adequate hardness at operating temperature

Common die materials include suitable tool steels and other specialized die materials.

9.34 Forging Machines

Important forging equipment includes:

Smith’s hammer

Power hammer

Drop hammer

Mechanical press

Hydraulic press

Screw press

Upset forging machine

9.35 Drop Forging

In drop forging, the upper die is raised and allowed to fall onto the workpiece, producing deformation through impact.

Important

Drop forging → Impact

9.36 Mechanical Press Forging

Mechanical presses use mechanical mechanisms such as:

Eccentric drives

Crank mechanisms

to convert rotary motion into controlled linear movement.

9.37 Hydraulic Press Forging

Hydraulic presses use hydraulic pressure to apply a controlled compressive force.

Advantages

Large force capacity

Smooth force application

Good control

Suitable for large forgings

9.38 Screw Press

A screw press uses rotational motion of a screw to generate forging force.

It can be used for:

Impression forging

Heading

Coining

Other forging operations

9.39 Advantages of Forging

Major advantages include:

High strength
Improved toughness
Good fatigue resistance
Refined grain structure under appropriate conditions
Reduced internal defects compared with some cast products
Favorable grain flow
High reliability

9.40 Grain Flow in Forging

One of the major advantages of forging is the development of favorable grain flow that follows the shape of the component.

This can improve:

Strength

Fatigue resistance

Toughness

Important

Forging → Directional grain flow

9.41 Disadvantages of Forging

Limitations include:

High equipment cost

High die cost

High initial investment

Shape limitations compared with some casting processes

Material waste in some die-forging operations due to flash

High forces required for cold forging

9.42 Forging Defects

Important forging defects include:

Cracks

Laps

Cold shuts

Flakes

Internal bursts

Underfilling

Die shift

Scale pits

Improper grain flow

9.43 Forging Laps

A lap is a surface defect caused by folding of metal over itself during forging.

It can result from:

Improper metal flow

Incorrect die design

Excessive deformation in a particular region

9.44 Internal Burst

An internal burst is an internal crack that can develop because of unfavorable stress conditions during deformation.

It may occur particularly when deformation conditions and material temperature are unsuitable.

9.45 Flakes

Flakes are internal cracks associated particularly with hydrogen and delayed cracking phenomena in certain steels.

They may be detected by appropriate inspection methods.

9.46 Scale

Scale forms on the surface of hot-forged material due to oxidation at elevated temperatures.

Excessive scale can affect:

Surface quality

Dimensional accuracy

Tool life

9.47 Underfilling

Underfilling occurs when the metal does not completely fill the die impression.

Possible causes include:

Insufficient material

Improper die design

Incorrect forging temperature

Inadequate forging force

9.48 Die Shift

Die shift occurs when the two die halves are not properly aligned.

It can produce:

Mismatch

Dimensional errors

Uneven geometry

9.49 Forging Temperature

The correct forging temperature depends on:

Material

Alloy composition

Forging operation

Required deformation

Equipment

There is no single forging temperature applicable to all metals.

9.50 Important Forging Revision

Term	Key Point
Forging	Plastic deformation by compressive force
Hot forging	High-temperature deformation
Warm forging	Intermediate temperature
Cold forging	Near-room-temperature deformation
Hammer forging	Impact
Press forging	Gradual pressure
Open-die	Dies do not completely enclose workpiece
Closed-die	Workpiece deforms within die cavity
Flash	Excess metal at die parting line
Upsetting	Length ↓, area ↑
Drawing out	Length ↑, area ↓
Fullering	Distributes metal
Edging	Gathers/redistributes metal
Bending	Produces angular/curved shape
Punching	Produces hole
Trimming	Removes flash
Heading	Produces fastener heads
Coining	High-pressure precision forging
Sizing	Improves dimensional accuracy
Roll forging	Deformation between rotating rolls
Drop forging	Impact
Hydraulic press	Controlled large compressive force
Lap	Folded-over metal defect
Flake	Internal crack associated with hydrogen
Underfill	Incomplete die filling
Die shift	Die misalignment

Q1. Forging is primarily a:

A. Casting process
B. Metal forming process
C. Machining process
D. Joining process

Answer: B. Metal forming process

Explanation: Forging changes the shape of metal through plastic deformation rather than removing material.

Practice

Q2. The principal force in forging is:

A. Tensile force
B. Compressive force
C. Shear force only
D. Bending force only

Answer: B. Compressive force

Explanation: Forging primarily involves plastic deformation under compressive loading.

Q3. A major advantage of forging is:

A. Favorable grain flow
B. High internal porosity
C. No deformation
D. Very low strength

Answer: A. Favorable grain flow

Explanation: Proper forging can produce grain flow that follows the component geometry, improving mechanical performance.

Q4. Hot forging is performed at:

A. Elevated temperature
B. Only absolute zero
C. Below the freezing point of the metal
D. Room temperature only

Answer: A. Elevated temperature

Explanation: The workpiece is heated sufficiently to facilitate plastic deformation.

Q5. Cold forging is generally carried out:

A. Near room temperature
B. Above the melting point
C. Inside a furnace only
D. At boiling temperature

Answer: A. Near room temperature

Explanation: Cold forging occurs without heating the workpiece to conventional hot-forging temperatures.

Q6. The major advantage of hot forging over cold forging is:

A. Lower deformation force
B. No oxidation
C. Higher dimensional accuracy in every case
D. Zero heating requirement

Answer: A. Lower deformation force

Explanation: Heating reduces the flow stress of many metals and makes large deformation easier.

Q7. Cold forging can improve strength mainly through:

WORKSHOP TECHNOLOGY & MANUFACTURING PROCESSES

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