Covers the principles of machining, measurement, tool grinding, and machine shop safety. This online course discusses the properties of metals, how to layout and set up a job, how to use measuring devices such as the micrometer and vernier caliper, and how to read working drawings

1. © rkm2003
Introduction
 Lathe is a machine, which removes the metal
from a piece of work to the required shape &
size
“Mother of Machine Tools “
Cylindrical and flat surfaces
 Turning Operations:
 Machine Tool – LATHE
 Job (work piece) – rotary motion
 Tool – linear motions

2. © rkm2003
The Lathe
Head stock
Spindle
Feed rod
Bed
Compound rest
and slide(swivels)
Carriage
Apron
selector
Feed change
gearbox
Spindle
speed
Lead screw
Cross slide
Dead center
Tool post
Guide ways
Tailstock quill
Tailstock
Handle

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Close view

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Lathe parts
Toolpost
 Fitted on top slide
and carries the
cutting tool or the
cutting tool holder

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Lathe parts
Tool holders
 Used for holding
cutting tool bits
 Available in Right
hand, left hand and
straight

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Cutting Tools
 Can be High Speed
Steel held in tool
holders
 Can be also Ceramic
(Tungsten carbide)
bits held directly in
toolpost

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Chucks
Three jaw Four Jaw

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Centers
Workpiece
Headstock center
(Live Centre)
Tailstock center
(Dead Centre)

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Turning Parameters
1. Cutting Speed v
2. Feed f
3. Depth of Cut d

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Cutting speed: The Peripheral Speed of Work piece
past the Cutting Tool
Feed:
The distance the tool advances for every
rotation of work piece (mm/rev)
Depth of Cut:
perpendicular distance between machined surface
and uncut surface of the Work piece
d = (D1 – D2)/2 (mm)
m/min
1000
N
D
v


D – Diameter (mm)
N – Revolutions per Minute
(rpm)

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Material Removal Rate
MRR
Volume of material removed in one
revolution MRR = D d f mm3
• Job makes N revolutions/min
MRR = D d f N (mm3/min)
 In terms of v MRR is given by
MRR = 1000 v d f (mm3/min)

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Operations on Lathe
 Turning
 Facing
 Grooving
 Parting
 Chamfering
 Taper turning
 Drilling
 Threading

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Turning ..
Cylindrical job: 1)Excess Material is removed
to reduce Diameter
2) a depth of cut of 1 mm will
b reduce diameter by 2
mm
Cutting
speed
Chip
Workpiece
Depth of cut (d)
Depth of cut
Tool
Feed
Chuck
N
Machined
surface

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Facing ..
 machine end of job Flat surface
or to Reduce Length of Job
 Turning Tool
 Feed: in direction perpendicular to workpiece axis
 Length of Tool Travel = radius of workpiece
 Depth of Cut: in direction parallel to workpiece axis
Depth of
cut
Feed
Workpiece
Chuck
Cutting
speed
Tool
d
Machined
Face

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Grooving
 Produces a Groove on workpiece
 Shape of tool shape of groove
 Carried out using Grooving Tool
Shape produced
by form tool Groove
Grooving
tool
Feed or
depth of cut
Form tool

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Parting
Tool is fed
radially into
rotating work
at some
location to cut
off end of part,
or provide a
groove

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Chamfering
Cutting edge
cuts an
angle on the
corner of the
cylinder,
forming a
"chamfer"

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Taper Turning
 Taper:
Methods
 Form Tool
 Swiveling Compound Rest
 Taper Turning Attachment
 Simultaneous Longitudinal and Cross Feeds
 C
B
A L
D
90°
 2
D1
L
D
D
2
tan 2
1 




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Taper Turning ..
By Form Tool

Taper
Workpiece
Straight
cutting edge
Direction
of feed
Form
tool

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Taper Turning ,,
By Compound Rest
Face plate
Dog

Tail stock quill
Tail stock
Mandrel
Direction of feed
Compound rest
Slide
Compound rest
Hand crank
Tool post &
Tool holder
Cross slide

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Threading
Pointed form tool
is fed linearly
across surface of
rotating workpart
parallel to axis of
rotation at a large
feed rate, thus
creating threads

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Drilling
Drill – cutting tool – held in TS –
feed from TS
Feed
Drill
Quill
clamp moving
quill
Tail stock clamp
Tail stock

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Example
A mild steel rod having 50 mm diameter and 500 mm
length is to be turned on a lathe. Determine the
machining time to reduce the rod to 45 mm in one
pass when cutting speed is 30 m/min and a feed of
0.7 mm/rev is used.
Given data: D = 50 mm, Lj = 500 mm v = 30 m/min, f
= 0.7 mm/rev
Substituting the values of v and D in
Machining time:
 t = 500 / (0.7 191)
= 3.74 minutes
m/min
1000
N
D
v


N = 191 rpm
min
N
f
L
t
j


25. © rkm2003
Example
 A 150 mm long 12 mm diameter stainless steel rod is to
be reduced in diameter to 10 mm by turning on a lathe
in one pass. The spindle rotates at 500 rpm, and feed is
0.4 mm/rev. Calculate the cutting speed, material
removal rate and the time required for machining the
steel rod.
Given data: Lj = 150 mm, D1 = 12 mm, D2 = 10
mm, N = 500 rpm
Using Equation (1)
v = 12 500 / 1000
= 18.85 m/min.
depth of cut = d = (12 – 10)/2 = 1 mm
From Equation : MRR = D d f N
MRR = 3.142 12 0.4 1 500 = 7538.4
mm3/min
t = 150/(0.4 500) = 0.75 min.
min
N
f
L
t
j


26. © rkm2003
Example
 Determine the angle at which the compound
rest would be swiveled for cutting a taper on a
workpiece having a length of 150 mm and
outside diameter 80 mm. The smallest diameter
on the tapered end of the rod should be 50 mm
and the required length of the tapered portion
is 80 mm.
 Given data: D1 = 80 mm, D2 = 50 mm, Lj = 80
mm (with usual notations)
tan = (80-50) / 2 80
or = 10.620
The compound rest should be swiveled at 10.62o

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Process sequence
From raw material of 175 mm length and 60
mm diameter a workpiece is to be made
which has been specified in the given figure
40 Dia
50
50 40
20
50
20 Dia
Threading

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Process sequence
A possible sequence for producing the
component would be:
 Turning (reducing completely to 50 mm)
 Facing (to reduce the length to 160 mm)
 Step turning (reducing from 50 mm to 40
mm)
 Thread cutting.
 Grooving