WORKSHOP TECHNOLOGY

WORKSHOP
TECHNOLOGY

NOR SYAKIROH TAJUDIN

JABATAN KEJURUTERAAN
MEKANIKAL
POLITEKNIK SEBERANG PERAI

WORKSHOP
TECHNOLOGY

Nor Syakiroh Tajudin
2021

Jabatan Kejuruteraan Mekanikal
Politeknik Seberang Perai

©All rights reserved. No part of this publication may be translated or reproduced in
any retrieval system, or transmitted in any form or by any means, electronic,
mechanical, recording, or otherwise, without prior permission in writing from
Politeknik Seberang Perai.

i

eBook PSP | Workshop Technology ii

All rights reserved

No part of this publication may be translated or reproduced in any retrieval system,
or transmitted in any form or by any means, electronic, mechanical, recording, or

otherwise, without prior permission in writing from Politeknik Seberang Perai.

Published by

Politeknik Seberang Perai
Jalan Permatang Pauh, 13500 Permatang Pauh

Pulau Pinang

Tel : 04-538 3322 Fax : 04-538 9266
Email : [email protected] Website : www.psp.edu.my
FB : politeknikseberangperai Ig : politeknikseberangperai

Perpustakaan Negara Malaysia Cataloguing-in-Publication Data

Nor Syakiroh Tajudin
WORKSHOP TECHNOLOGY / NOR SYAKIROH BINTI TAJUDIN.
Mode of access: Internet
eISBN 978-967-0783-87-1
1. Workshops--Equipment and supplies.
2. Government publications--Malaysia.
3. Electronic books.
I. Title.
621.9

iii eBook PSP | Workshop Technology

Acknowledgement

First and foremost, I would like to praise Allah the Almighty, the Most Gracious, and
the Most Merciful for His blessing given to me in completing this eBook. I would like
to express my gratitude and sincere thanks to Head of Mechanical Department, En Mr.
Muhammad Nasir Bin Marzuki , who has given me his valuable guidance, advice and
encouragement so I could complete this ebook in time. My ultimate thanks is dedicated
to my beloved family and friends for their endless support, love, and prayer. Special
thanks to to the director of Politeknik Seberang Perai, Sr. Harith Fadzilah Bin Abd
Khalid for his guidance, understanding and invaluable advices throughout the duration
of this writing and publishing this eBook.

Nor Syakiroh Tajudin

eBook PSP | Workshop Technology iv

Preface

Workshop Technology eBook is a clear and practical guide written for Semester 1
students of Mechanical Engineering Department. This eBook is an essential reading
for all students of engineering who are taking a course in workshop or seeking a
resource to aid their assignments. The eBook has been written in a logical sequence
so that the students can move on to complex manufacturing processes after acquiring
knowledge about the basics of processes and materials.

v eBook PSP | Workshop Technology Pages

Table of Content 1
1
Chapter 2
3
CHAPTER 1: HANDTOOLS 4
1.1 Introduction to Handtools 6
1.2 Marking Out 7
1.3 Testing Tools 8
1.4 Hack Saw 9
1.5 Files And Filling Work
1.6 Hammer 16
1.7 Chisel 17
1.8 Taps And Dies 18
1.9 Measurement 19
19
CHAPTER 2: DRILLING
2.1 Introduction to Drilling Machine 21
2.2 Spindle Speed Revolution 21
2.3 Feed Rate 21
2.4 Cutting Fluids 23
2.5 Standard Operation Procedure 23
23
CHAPTER 3: LATHE MACHINE 24
3.1 Introduction to Lathe Machine 27
3.2 Types Of Lathe Machines
3.3 Parts Of Lathes Machine
3.4 Work Holding Devices
3.5 Tool Angle
3.6 Material Used In Tool Bit
3.7 Lathe Operations
3.8 Setting Cutting Tools

eBook PSP | Workshop Technology vi

CHAPTER 4: MILLING MACHINE 28
28
4.1 Introduction to Milling Machine 30
4.2 Types Of Milling Machines 30
4.3 Universal Milling Machine 31
4.4 Basic Principles Of Milling Machine 32
4.5 Methods Of Milling Process 33
4.6 Types Of Milling Cutter 33
4.7 Milling Operations 33
4.8 Method Of Holding Cutting Tools 34
4.9 Methods Of Holding A Work Piece 34
4.10 Revolution Per Minute (Rpm), Feed Rate And Cutting Time
4.11 Feed Rate 36
36
CHAPTER 5: GEAR 39
5.1 Introduction to Gear 39
5.2 Types Of Gears 40
5.3 Parts Of Spur Gear 40
5.4 Measurement And Testing Of Gears
5.5 Symbol In Gear 43
5.6 Plug Method For Pitch Diameter And Divide Of Teeth 43
44
CHAPTER 6: COMPUTER NUMERICAL CONTROL (CNC) 44
6.1 Introduction to Computer Numerical Control (CNC) 45
6.2 NC Operation 45
6.3 CNC Axis Conventions 45
6.4 Programming Codes 54
6.5 Linear Interpolation 54
6.6 Circular Interpolation
6.7 Types Of Control System 55
6.8 Advantages Of Computer Numerical Control 61
6.9 Disadvantages Of Computer Numerical Control 66
70
CHAPTER 7: WELDING 72
7.1 Introduction to Shield Metal Arc Welding (SMAW) 72
7.2 Introduction to Oxy Acetylene Welding
7.3 Introduction to Metal Inert Gas (MIG) 76
7.4 Introduction to Tungsten Inert Gas (TIG) vii
7.5 Weld Defects And Its Prevention
7.6 The Types Of Weld Defects

Summary
References

1CHAPTER1 eBook PSP | Workshop Technology

HANDTOOLS

1.1 Introduction to Handtools

There are many types of handtools in engineering field. To get an accurate measurement and
produce high quality work piece, the fitting work is the main role in engineering workshop.
So, it’s important to know the function of each tool. The tools that are used in workshop can
be classified into these following groups:

Table 1.1 Class of Handtools

Activity Tools

Measuring Steel rule, inside & outside calliper, vernier caliper, micrometer,
high gauge, L-square
Marking out
Scriber, centre punch, divider, surface plate, steel ruler, high
Checking/testing gauge, surface table
Cutting L-square, straight edge, surface plate, high gauge
Strickling Chisel, Hacksaw, files
Holding All types of hammers
Drilling All types of vise
Threading All types of drills
Tap and dies

1.2 Marking Out

Marking out is the process of marking a spot or line on the metal surface before machining
processing marking tools. In other word, we transfer the design or pattern to a workpiece as
preparation for the next step, machining or manufacture.

eBook PSP | Workshop Technology 2

1.2.1 Marking Tools

a. Scriber
It is made of steel and one end is sharp pointed and other end is similar but bent. This
tool is used for scribing line on workpiece.

b. Center Punch
This tool is used for making center for drilling.

c. Divider
It is used chiefly for spacing, scribing, circling and layout work. Reading maybe taken or
transferred from the steel rule to the workpiece. It also can be used to test and measure
the distance.

d. Surface Plate
Layout work may be performed on a layout table or on a surface plate made of granite or
cast iron. Surface plate generally have three-point suspension to prevent rocking when
mounted on an uneven surface.

1.3 Testing Tools

a. L- Squares
It used to lay out lines at right angle (90o) to a machine edge, to test the accuracy of
surfaces that must be square (90o to each other) and to set up work for machining.

b. Surface Gauge
It is used with a surface plate or any flat surface to scribe layout lines on a work piece.

3 eBook PSP | Workshop Technology

c. Straight Edge
It is a tool with an edge free from curves, or straight, used for transcribing straight lines,
or checking the straightness of lines. If it has equally spaced markings along its length. It is
usually called a ruler.

1.4 Hack Saw

A hacksaw is a metal-framed saw used primarily for cutting plastic and metal pipes and other
small household materials.
Parts Of Hacksaw
a. The solid frame is more rigid and will accommodate blades of only one specific length.
b. The adjustable frame is more commonly used and will take blades which range from 250
to 300 mm long.
c. A wing nut provides adjustment for blade tensioning
d. Blades are made of high speed molybdenum or tungsten alloy steel that has been hardened
and tempered. They are two types: the solid and the flexible blade.

Figure 1.1 Hack Saw

eBook PSP | Workshop Technology 4

1.5 Files And Filling Work

Parts Of File

A files is a hand cutting tool made of high-carbon steel. It has a series of teeth cut on its body
by parallel chisel cuts. Files are manufactured in a variety of types and shapes. Each file is used
for a specific purpose. They may be divided into two classes: single-cut and double-cut

Figure 1.2 Parts of file

Types And Shapes
a. Mill File
b. Pillar File
c. Round File
d. Square File
e. Taper File
f. Three-Square File

Techniques In Filing Process
1. Cross Filing
a. Hand files are normally held in both hands.
b. The file is held flat against the surface it is cut / smooth.
c. The file is then pushed forward and it cuts on the forward stroke.
d. It is then lifted away from the metal and returned to the starting point for the next push

forward.

5 eBook PSP | Workshop Technology

Figure 1.3 Cross Filing

2. Draw Filing
a. If the surface produces by through filing is not good enough, the next stage is draw filing.
b. The file is held in both hand by the blade.
c. The file is pushed forwards and backwards along the material.
d. This will further smooth the material.

Figure 1.4 Draw Filing

Safety Precautions
a. Do not store files where they will rub together. Hang them separately
b. Never use a file as a pry or a hammer. Since the file is hard, it snaps easily, often causing

small pieces to fly that may result in serious eye injury.
c. Always use a file card or brush to clean it
d. Apply pressure only on the forward stroke when filling. Pressure on the return stroke

will dull the file.
e. Do not press too hard on a new file. Too much pressure tends to break off the cutting

edges and shorten the life of the file.

eBook PSP | Workshop Technology 6

1.6 Hammer

Hammers is an important tools that used to drive nails or tacks and break objects apart. The
hammers are a useful tool that come in a wide array of styles and sizes. It may have steel,
fiberglass or wooden shafts, or handles. All hammers have at least one striking face, which is
the side of the hammer that is used to drive fasteners into wood or other materials

Types Of Hammers
There are many types of hammers such as:
a. Claw Hammer
b. Pin Hammer
c. Cross Pein Hammer
d. Ball Peen Hammer
e. Club Hammer
f. Soft Faced Hammer
g. Mallet
h. Sledge Hammer

Ball Peen Hammer

Sometimes called mechanic’s hammers, ball peen hammers have the same circular flat
striking face as claw and the smaller, rounded end is the peen.

Figure 1.5 Ball Peen Hammer

7 eBook PSP | Workshop Technology

Safety Precautions
The following safety precautions should always be observed when using a hammer:
a. Be sure that the handle is solid and not cracked
b. See the head is tight on the handle and secured with a proper wedge to keep the handle

expanded in the head
c. Never use a hammer with a greasy handle or when your hands are greasy.
d. Never strike two hammer faces together. The faces have been hardened and a metal chip

may fly off, causing an injury
e. Always wear safety glasses when driving masonry nails or breaking up concrete.

1.7 Chisel

Chisel is produced from steel used to obtain a flat and finished surface. There are various type
of chisels such as flat chisel, diamond tip chisel, cape chisel, horizontal tip, edge round and
nose chisel.

Types Of Chisels

The cutting end of a cold chisel may be shaped in one of several forms depending on the
purpose for which it is to be used.

a. Flat chisel
The cold or flat chisel is used for chipping and sometimes for shearing off metal. The
metalworker may use a chisel for chipping, grooving or for shearing.

b. Cape chisel
The cape chisel is used for cutting rectangular grooves such as keyways. Its cutting edge
is made wider than the stock immediately behind it to give clearance to the edge.
Without this clearance it would bind in the groove as it cut.

eBook PSP | Workshop Technology 8

c. Diamond-point chisel
The diamond-point chisel is used to cut a V-shaped groove. .It can be used to open a crack
in a casting in preparation for welding. Sometimes, when a part is to be taken off a
casting, instead of sawing it off it is grooved with a diamond-point chisel and then broken
off with a hammer or sledge blow.

Safety Precautions
a. Clamp work securely, unless the material being chipped is heavy enough to resist

movement caused by the blows of the hammer on the chisel, it should be secured in a
vice or otherwise prevented from moving.
b. Hands should be cleaned from grease before holding the chisel
c. The work should therefore be done in a way that will not create a hazard to other people,
or the work secured in such a manner as to prevent this.
d. Avoid using mushroom head chisel- causing chips to fly away from the operator, always
wears protective eye shields.

1.8 Taps And Dies

a. Taps and dies are cutting tools used to create screw threads, which is called threading.
b. A tap is used to cut the female portion of the mating pair. It is used to make internal

thread (nut).
c. A die is used to cut the male portion of the mating pair. It is used to make external thread

(screw).

9 eBook PSP | Workshop Technology

1.9 Measurement

1.9.1 Introduction Of Measurement

Measuring a workpiece accurately is very important in a mechanical workshop. There are
many types of measuring tool in mechanical workshop.

Measurement Tools In Mechanical Workshop
a. Steel ruler
b. High gauge
c. Measuring tape
d. Vernier Caliper
e. Micrometer
f. Internal caliper
g. External caliper
The tools that always used in taking readings are vernier caliper and micrometer.

1.9.2 Micrometers

A micrometer is a measuring device resembling a C-clamp designed to precisely measure the
lengths, diameters and thicknesses of solid objects.

Types Of Micrometers
a. Inside Micromet
b. Outside Micrometer
c. Depth Micrometer
d. Digital Micrometer

eBook PSP | Workshop Technology 10

Parts Of Micrometer

Figure 1.6 Parts of Micrometer

How To Read The Measured Value
Using the first example seen below:

Figure 1.7 Micrometer Reading

a. Read the scale on the sleeve. The example clearly shows 12 mm divisions.
b. The scale on the sleeve, a further ½ mm (0.5) measurement can be seen on the bottom

half of the scale. The measurement now reads 12.5mm.
c. Finally, the thimble scale shows 16 full divisions
d. The final measurement is 12.5mm + 0.16mm = 12.66

11 eBook PSP | Workshop Technology

1.9.3 Vernier Caliper

a. The vernier scales will often include both Metric and Imperial unit of measurements on
the upper and lower part of the scale.
b. Vernier calipers commonly used in industry provide a precision to a hundredth of a
millimetre (10 micrometres), or one thousandth of an inch.
c. A more accurate instrument used for the same purpose is the micrometer.

Parts Of Vernier Caliper

Figure 1.8 Parts of Vernier Caliper

a. Outside jaws
b. Inside jaws
c. Depth probe
d. Main scale (metric)
e. Main scale (inch)
f. Vernier (metric)
g. Vernier (inch)
h. Retainer used to block movable part to allow the easy transferring a measurement.

Types Of Calipers
1. External Caliper
a. Outside calipers are used to measure the external size of an object.
b. They are especially useful when measuring over very large distances, consider if the

calipers are used to measure a large diameter pipe.
2. Internal Caliper
a. The internal calipers are used to measure the inside diameter of an object.

1.9.10 How To Read The Measured Value

a. Read the centimeter mark on the fixed scale to the left of the 0-mark on the vernier
scale. (10mm / 1cm on the fixed caliper).

Figure 1.9 First reading
b. Find the millimeter mark on the fixed scale that is just to the left of the 0-mark on the

vernier scale. (6mm/ 0.6cm on the fixed caliper).

Figure 1.10 Second reading

12

13 eBook PSP | Workshop Technology

c. Look along the ten marks on the vernier scale and the millimeter marks on the adjacent
fixed scale, until you find the two that most nearly line up. (0.25mm / 0.025cm on the
vernier scale).

Figure 1.52 Last reading
d. To get the correct reading, simply add this found digit to your previous reading.
e. Total measurement is 10mm + 6mm + 0.25mm = 16.25 mm /

1cm + 0.6cm + 0.025cm = 1.625cm

eBook PSP | Workshop Technology 14

Exercise 1

a.

b.

c.
d.

15 eBook PSP | Workshop Technology

e.
f.

g.

2CHAPTER eBook PSP | Workshop Technology 16

DRILL

2.1 Introduction to Drilling Machine

The drilling machine is important part in any metalworking shop. A drilling machine is used to
produce holes in metal. However, operations such as tapping, reaming, counter boring,
countersinking, boring and spot-facing can also be performed using drilling machine.

Twist Drill Bit
Twist drills are end cutting tools that used to produce holes in most types of material. Most
twist drills used in machine shop work today are made of high-speed steel. A drill may be
divided into 3 main parts such as shank, body and point.

Figure 2.1 Twist Drill Bit

Determining The Drill Sizes
Drill sizes are designated under four systems: fractional, number, letter and millimetre (metric
sizes.
a. Fractional sizes - drills range from 1/64 to 4 inch,
b. Number size - drills range from #1 to #97,
c. Letter size – drills range from A to Z.
d. Millimeter (metric) - drills are produced in a wide variety of sizes. Miniature metric drills

range from 0.04 to 0.09 mm. Straight shank standard metric drills are available in sizes
from 0.5 to 20 mm. Taper-shank metric drills are manufactured in sizes from 8 to 80 mm
Drill sizes may be checked by using a drill gage.

17 eBook PSP | Workshop Technology

Steps Of Marking Out Before Drilling
During the drilling operation, it may be necessary to draw the drill point over so that it is
concentric with the layout.
a. Clean the surface of the workpiece
b. Draw two lines, intersect with each other
c. Lightly prick-punch where two lines intersect
d. With pair of dividers, scribe a circle to indicate the diameter of the hole required
e. Scribe a test circle, 1.5 mm smaller than the hole size
f. Dot punch at suitable intervals
g. Center drill the work

Method Of Holding A Drill Bit
The different methods used for holding drill in a drill spindle are:
a. By directly fitting in the spindle hole.
b. By using drill sleeve
c. By using drill socket
d. By using drill chuck

2.2 Spindle Speed Revolution

The most economical drilling speed depends on many variables, such as:
a. Type and hardness of material
b. Diameter and material of drill
c. Depth of hole
d. Type and condition of drill press
e. Efficiency of cutting fluid employed
f. Accuracy and quality of hole required

eBook PSP | Workshop Technology 18

Spindle speed / Revolution per minute
Formula (Metric)

r / min = CS x 1000
D

Convert all units are in mm

Example 1

Calculate r/min required to drill 15 mm hole in tool steel (CS 18) using a high-speed steel

drill r / min = CS x 1000 = 18 x 1000 = 18000 = 381.92r / min
D 15 47.13

2.3 Feed Rate

Factors depend on:
a. Depth and width of cut
b. Design or type of cutter
c. Sharpness of cutter
d. Work piece material
e. Strength and uniformity of work piece
f. Type of finish and accuracy required
g. Power and rigidity of machine, holding device and tooling setup

Formula

F = no. of cutter teeth x feed/tooth x cutter r/min
Feed (mm/min) = N x CPT x r/min

19 eBook PSP | Workshop Technology

2.4 Cutting Fluids

Basically a good cutting fluid should:
a. Cool the work piece and tool
b. Reduce friction
c. Improve the cutting action
d. Protect the work against rusting
e. Provides antiweld properties
f. Wash away the chips
****Oil: good lubricant, poor coolant
****Water: best coolant, no lubricating value (promotes rust)

2.5 Standard Operation Procedure

Personal Protective Equipment (Ppe)

Figure 2.2 PPE

eBook PSP | Workshop Technology 20

Pre-Operational Safety Checks
a. Locate and ensure you are ready wearing PPE.
b. Ensure all guards are fitted, secure and functional. Do not operate if guards are missing
or faulty.
c. Check workspaces and walkways to ensure no slip/trip hazards are present.
d. Ensure the chuck key (if used) has been removed from the drill chuck.
e. Use the suitable clamping to hold the workpiece.
f. Adjust the spindle speed to suit drill or cutter diameter.
g. Use cutting fluids before drilling process

Operational Safety Checks
a. Before making adjustments or before cleaning swarf accumulations, switch off and bring

the machine to a complete standstill.
b. Feed downwards at a sufficient rate to keep the drill cutting.
c. Feed with care as the drill breaks through the underside of the work.
d. Use a safe working posture.

Ending Operations And Cleaning Up
a. Switch off the machine when work completed.
b. Leave the machine in a safe, clean and tidy state.

Potential Hazards And Injuries
a. Hair/clothing getting caught in moving machine parts.
b. Eye injuries.
c. Flying swarf and chips.
d. Sharp edges and burrs.

Don’t
a. Do not use faulty equipment. Immediately report suspect equipment.
b. Never leave the machine running unattended.
c. Do not hold the item being drilled with your hands. Use a clamp.

3CHAPTER21 eBook PSP | Workshop Technology

LATHE MACHINE

3.1 Introduction to Lathe Machine

The lathe machine is used to manufacture cylindrical parts only. The products are from a
range of materials including steels and plastics. Many of the components that go together to
make an engine work have been manufactured using lathes. These may be lathes operated
directly by manual or using Computer Numerical Controlled (CNC machines).

3.2 Types Of Lathe Machines

a. Turret lathe
b. Lathe capstans
c. Automatic lathes
d. Special purpose lathes
e. N.C and C. N. C lathe

3.3 Parts Of Lathes Machine

Figure 3.1 Parts of center lathe machine

eBook PSP | Workshop Technology 22

Main Parts of Lathe Machine
a. Bed: supports all major components
b. Headstock – Holds the jaws for the work piece, supplies power to the jaws and has various

drive Speeds
c. Tailstock – supports the other end of the work piece

Carriage Feed
a. Longitudinal Feed or “Turning” - The tool is fed along the work.
b. Cross slide or “Facing” – The tool is fed across the work.

Tail Stock
a. It’s like a stationary drill press
b. It is centered with your work piece
c. For drilling use a drill chuck that fits your bits
d. Jam the drill chuck into the tail stock
e. To remove the chuck turn the tail stock back to zero and the chuck should pop out

Tool Post
a. Fitted on top slide and carries the cutting tool or the cutting tool holder
b. Can adjust the height on some types
c. Can carry 4 different tool holders

Tool Holders
a. Used for holding cutting tool bits
b. Available in Right hand, left hand and straight

23 eBook PSP | Workshop Technology

3.4 Work Holding Devices

a. Three Jaw chuck
b. Four Jaw chuck
c. Magnetic chuck
d. Face plates
e. Mandrels

3.5 Tool Angle

Clearance angle
a. Ensures only the cutting edge of the tool touches the work
b. Too much clearance causes chatter

Rake Angle
a. Allows the chip being cut to flow out
b. Changing the rake changes the power used in cutting and the heat generated
c. Large rake = soft ductile materials
d. Small rake = hard brittle materials

3.6 Material Used In Tool Bit

Types of material tool bit such are:
a. High Speed Steel held in tool holders
b. Ceramic (Tungsten carbide) bits held directly in tool post

eBook PSP | Workshop Technology 24

3.7 Lathe Operations

a. Parallel turning
b. Facing off
c. Knurling
d. Parting off / Grooving
e. Thread cutting
f. Drilling
g. Chamfering
h. Tapering
i. Boring

Parallel Turning

The tool moved parallel to the work and cylindrical shapes are formed. This process also
known as sliding process. It is use to reduce diameter of object.
The student can parallel turn the work on the lathe manually or use the automatic traverse
option.

Figure 3.2 Parallel turning process

Facing Off
The tool is moved at right angles to the work using the cross slide. Flat surfaces are produced.
It is use to reduce length of project.

25 eBook PSP | Workshop Technology

Figure 3.3 Facing off process
Knurling
A knurling process is a process that presses a pattern onto a round section. The pattern is
normally used as a grip for a handle. This provide a grip for the round part such as screwdriver

Figure 3.4 Knurling tool
Parting Off/ Grooving
If the student wants to cut off the part they have turned, they can use the hacksaw and a vice
or use the parting off tool on the lathe.

Figure 3.5 Parting off tool

eBook PSP | Workshop Technology 26

Threading
There are threading process in lathe machine. This threads take up different profiles (60°)
ACME etc. These threads can be seen on bench vices and lathes.

Figure 3.6 Screw thread
Drilling
The drilling process is using tailstock to support the drilling bit.

Figure 3.7 Drilling Process
Chamfering
Cutting edge cuts an angle on the corner of the cylinder, forming a chamfer.

Figure 3.8 Chamfering process

27 eBook PSP | Workshop Technology

Tapering
Feed a tool at an angle to the length of the workpiece in order to create a conical shape.

Figure 3.9 Tapering process
Boring
Boring is the enlarging and truing of a hole by removing material from internal surfaces with
a single-point cutter bit.

Figure 3.10 Boring process

3.8 Setting Cutting Tools

The cutting tool on the lathe must be set to the exact centre of the work-piece to get an
accurate result. We use the centre of the tailstock to guide us to the correct height

Figure 3.11 Setting cutting tool

4CHAPTER eBook PSP | Workshop Technology 28

MILLING MACHINE

4.1 Introduction to Milling Machine

Milling machine is one of the most versatile conventional machine tools with a wide range of metal
cutting capability. It used to produce one or more machined surfaces accurately on a piece of
material.
This is done by one or more rotary milling cutters having single or multiple cutting edges.
The work piece is held securely on the work table of the machine or in a holding device
clamped to the table. It is then brought into contact with a revolving cutter.

Figure 4.1 Milling machine

4.2 Types Of Milling Machines

A. Column & knee type milling machine:
a. Plain Horizontal milling machine
b. Universal Horizontal milling machine
c. Vertical milling machine

29 eBook PSP | Workshop Technology

B. Production milling machine
C. Automatic milling machine (special type)
Vertical Milling Machine

Figure 4.2 Vertical milling machine
Horizontal Milling Machine

Figure 4.3 Horizontal milling machine

eBook PSP | Workshop Technology 30

Universal Milling Machine

Figure 4.4 Universal horizontal milling machine

4.3 Universal Milling Machine

Difference from plain horizontal machine is addition of table swivel housing
1. Located between table and saddle
2. Permits table to be swivelled 45º in either direction in a horizontal plane. Used for milling

of helical grooves in twist drills, milling cutters, and gears

4.4 Basic Principles Of Milling Machine

Working Principle:
a. The work piece is holding on the worktable of the machine.
b. The table movement controls the feed of work piece against the rotating cutter. The

cutter is mounted on a spindle or arbor and revolves at high speed.
c. Except for rotation the cutter has no other motion.
d. As the work piece advances, the cutter teeth remove the metal from the surface of work

piece and the desired shape is produced.

31 eBook PSP | Workshop Technology

4.5 Methods Of Milling Process

Up Milling
a. Also called conventional milling,
b. Wheel rotation opposite of the feed
c. The chip formed by each cutter tooth starts out very thin and increases its thickness
d. The length of the chip is relatively longer
e. Tool life is relatively shorter
f. Need more clamping force to hold the work part still.

Figure 4.6 Up cut milling
Down Milling
1. Also called climb milling,
2. Wheel rotation is parallel to the feed
3. The chip formed by each cutter tooth starts out thick and leaves out thin
4. The length of the chip is relatively short
5. Tool life is relatively longer
6. Need less clamping force to hold the work part still.

Figure 4.7 Down cut milling

eBook PSP | Workshop Technology 32

4.6 Types Of Milling Cutter

Cutting Tools for Horizontal Milling
a. Slab Mills

For heavy cutting of large and flat surfaces.

b. Side and Face Cutters
For cutting shoulders and slots.

c. Slitting Saws
For cutting deep slots or for parting off.

Cutting tools for Vertical Milling
a. End Mills

Commonly used for facing, slotting and profile milling.

b. Rough Cut End Mills
For rapid metal removal.

c. Slot Drills
For producing pockets without drilling a hole.

d. Face Milling Cutters
For heavy cutting.

e. Woodruff Milling Cutter
Used to cut the keyways. It is a very important piece for key maker.

f. Dovetail Milling Cutter
Used primarily for machining / cutting angled dovetail grooves or joints in a workpiece.

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4.7 Milling Operations

a. Plain Milling (Slab Milling)
b. Face Milling
c. End Milling
d. Side Milling
e. Straddle Milling
f. Angular Milling
g. 4gang Milling
h. Form Milling
i. Profile Milling
j. Keyways, Grooves & Slots Milling
k. Thread Milling

4.8 Method Of Holding Cutting Tools

a. Collect
b. Arbor
c. Sleeves
d. Adapters

4.9 Methods Of Holding A Work Piece

The commonly used are:
a. Plain Vise- Jaws parallel or 90º to axis of spindle
b. Swivel Base Vise -Can swivel through 360º in horizontal plane
c. Universal Vise - Can swivel through 360o in horizontal plane and tilted from 0o to 90o in

vertical plane
d. Rotary Table
e. Angle Plate

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4.10 Revolution Per Minute (Rpm), Feed Rate And Cutting Time

Revolution per Minute (Rpm)
There are several factors must be considered when determining the proper r/min at which to
machine a metal. The most important are:
a. The type of work material
b. The cutter material
c. The diameter of the cutter
d. The surface finish required
e. The depth of cut taken
f. The rigidity of the machine and work setup

Formula

4.11 Feed Rate

Factors depend on:
a. Depth and width of cut
b. Design or type of cutter
c. Sharpness of cutter
d. Work piece material
e. Strength and uniformity of work piece
f. Type of finish and accuracy required
g. Power and rigidity of machine, holding device and tooling setup

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Formula

F = no. of cutter teeth x feed/tooth x cutter r/min
Feed (mm/min) = N x CPT x r/min

Safety Procedure
a. Do not make contact with the revolving cutter.
b. Place a wooden pad or suitable cover over the table surface to protect it from possible
damage.
c. Use the buddy system when moving heavy attachments.
d. Do not attempt to tighten arbour nuts using machine power.
e. When installing or removing milling cutters, always hold them with a rag to prevent
cutting your hands.
f. While setting up work, install the cutter last to avoid being cut.
g. Never adjust the workpiece or work mounting devices when the machine is operating
h. Chips should be removed from the workpiece with an appropriate rake and a brush

5CHAPTER eBook PSP | Workshop Technology 36

GEAR

5.1 Introduction to Gear

Gears can be manufactured by casting, forging, extrusion, drawing, thread rolling, powder
metallurgy, and blanking sheet metal process. Nonmetallic gears can be made by injection
moulding and casting.

5.2 Types Of Gears

a. Spur gear
b. Internal gears
c. Helical gears
d. Herringbone gears
e. Bevel gears
f. Miter gears
g. Angular bevel gears
h. Hypoid gears
i. Worm and worm gear
j. Rack and pinion gear

Spur Gear
a. Generally used to transmit power between two parallel shafts.
b. The teeth on these gears are straight and parallel to the shafts to which they are attached.
c. When two gears of different sizes are in mesh, the larger is called the gear while the

smaller is called the pinion.
d. Spur gears are used where slow to moderate- speed drive are required

37 eBook PSP | Workshop Technology

Internal Gear
a. Used where the shafts are parallel and the centers must be closer together and that could

be achieved with spur or helical gearing.
b. This arrangement provides a stronger drive since there is the greater area of contact than

with the conventional gear drive.
c. It also provides speed reductions with a minimum space requirement.
d. Internal gears are used on heavy duty tractors where much torque is required.

Helical Gear
a. Used to connect parallel shafts or shafts which are at an angle.
b. Because of the progressive rather than intermittent action of the teeth, helical gears run

more smoothly and quietly than spur gears.
c. Since there is more than one tooth in engagement at any one time, helical gears are

stronger than spur gears of the same size and pitch.
d. However, special bearing (thrust bearings) are often required on shafts to overcome the

end thrust produced by these gears as they turn.

Herringbone Gear
a. Resembles of two helical gears placed side by side, with one half having a left-hand helix

and the other half a right-hand helix.
b. These gears have a smooth continuous action and eliminate the need for thrust bearings.

Bevel Gear
a. When two shafts are located at an angle with their axial lines intersecting at 90o, power

is generally transmitted by means of bevel gears.

Miter Gear
a. When the shafts are at right angles and the gears are of the same size they are called

miter gears

eBook PSP | Workshop Technology 38

Angular Bevel Gears
a. It is not necessary that the shafts be only at right angles in order to transmit power.
b. If the axes of the shafts intersect at any angle other 90° the gears are known as angular

bevel gears

Hypoid Gear
a. Modified bevel gears having helical teeth are known as hypoid gears.
b. The shafts of these gears, although at right angles, are not in the same plane and,

therefore, do not intersect.
c. Used in automobile drives

Worm and Worm Gear
a. When shafts are at right angles and considerable reduction in speed is required, a

worm and worm gear may be used.
b. The worm, which meshes with the worm gear, may be single or multiple start thread.
c. A worm with a double-start thread will revolve the worm gear twice as fast as a worm

with a single-start thread and the same pitch.

Rack and Pinion
a. When it is necessary to convert rotary motion to linear motion, a rack and pinion may be

used.
b. The rack, which is actually a straight or flat gear, may have straight teeth to mesh with a

spur gear, or angular teeth to mesh with a helical gear.

39 eBook PSP | Workshop Technology

5.3 Parts Of Spur Gear

Figure 5.1 Parts of Spur Gear

5.4 Measurement And Testing Of Gears

Gear-tooth Vernier Caliper
a. The gear-tooth Vernier, is an instrument for measuring the pitch-line thickness of a tooth.
b. It has two scales and must be set for the width (w) of the tooth, and the depth (h) from
the top, at which the width occurs.

Figure 5.2 measuring Gear

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5.5 Symbol In Gear

a. T/t = No. of teeth
b. P = Diametral pitch ( inch gear )
c. P = Circular pitch
d. D/d = Diameter of pitch circle
e. R/r = Radius of pitch circle
f. Y = pressure angle
g. M = Modul
h. Add/A = Addendum
i. Ded/D = Dedendum
j. Circular pitch = P x Modul M

5.6 Plug Method For Pitch Diameter And Divide Of Teeth

Figure 5.3 Plug Method

Example 1

Calculate for a tooth space of a 5 mm module gear with its centre on the pitch circle. If the
gear has 36T, find: (a) Diameter of plug (ɣ = 20˚), (b) Distance over two such plugs spaced in
opposite spaces & (c) Distance over two plugs spaced 10 teeth apart

a. Diameter of plug = Пm cos ɣ
2

= 5П cos 20˚
2

= 7.38 mm

41 eBook PSP | Workshop Technology

b. Distance over two such plugs spaced in opposite spaces,
= Pitch dia of gear + diameter of plug

Pitch dia of gear = mT
= 5 x 36
= 180 mm

So, = 180 mm + 7.38 mm
= 187.38mm

c. Distance over two plugs spaced 10 teeth apart

Figure 5.4 Sketching answer

Angle subtended by 10 teeth = N x 360 = 10 X 360 = 1000
T 36

In triangle OAB:
AB = OA sin 50o

= 90 x 0.766
= 68.94

Centre distance of plugs = 2 x AB
= 2 x 68.94
= 137.88 mm.

Distance over plugs (10 teeth) = 137.88 + 7.38
= 145.26 mm

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Example 2

A spur gear has PD of 60mm and 20 teeth. Calculate:
a. Modul
b. Circular Pitch
c. Addendum
d. Outside diameter
e. Dedendum

a. Modul = PD/N
= 60/20
= 3 mm

b. CP =M×П
= 3 × 3.1416
= 9.425 mm

c. Addendum = Modul
= 3 mm

d. Outside diameter = PD + 2M
= 60 + 2(3)
= 66 mm

e. Dedendum = M × 1.166
= 3 × 1.166
= 3.498 mm

6CHAPTER43 eBook PSP | Workshop Technology

COMPUTER NUMERICAL CONTROL (CNC)

6.1 Introduction to Computer Numerical Control (CNC)

Computer Numerical Control (CNC) is one in which the functions and motions of a machine
tool are controlled by coded alphanumeric data. CNC also can control the motions of the
workpiece or tool, the input parameters such as feed, depth of cut, speed, and the functions
such as turning spindle on/off, turning coolant on/off.

Figure 6.1 Computer Numerical Control Machine (CNC)

6.2 NC Operation

CNC stands for Computer Numerical Control. The functions of a CNC Controller are:
a. To read and store programmed information.
b. To interpret the information in a logical command sequence.
c. To control the motion of the machines mechanical members.
d. To monitor the status of the machine.