Lathe Operation

7/29/2019 Lathe Operation

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Turning Operations

L a t h e


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Turning Operations

Machine Tool LATHE

Job (workpiece) rotary motion

Tool linear motions

Mother of Machine Tools

Cylindrical and flat surfaces


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Some Typical Lathe Jobs

Turning/Drilling/Grooving/

Threading/Knurling/Facing...


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The Lathe

Head stock

Spindle

Feed rod

Bed

Compound rest

and slide(swivels)

Carriage

Apron

selector

Feed change

gearbox

Spindlespeed

Lead screw

Cross slide

Dead center

Tool post

Guide ways

Tailstock quill

Tailstock

Handle


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The Lathe

Bed

Head StockTail Stock

CarriageFeed/Lead Screw


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Types of Lathes

Engine Lathe

Speed Lathe Bench Lathe

Tool Room Lathe

Special Purpose Lathe

Gap Bed Lathe


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Size of Lathe

Workpiece Length Swing


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Size of Lathe ..

Example: 300 - 1500 Lathe

Maximum Diameter of Workpiece that can be machined

= SWING (= 300 mm)

Maximum Length of Workpiece that can be held between

Centers (=1500 mm)


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WorkholdingDevices

Equipment used to hold Workpiece fixtures

Tool -jigs

Securely HOLD or Support while machining


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Chucks

Three jaw Four Jaw

Workh

olding

Devices..


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Centers

Workpiece

Headstock center

(Live Centre)

Tailstock center

(Dead Centre)

Workh

olding

Devices..


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Faceplates

W

orkpiece

Workh

olding

Devices..


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Dogs

Workh

olding

Devices..

Tail

Tail


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Mandrels

Workpiece (job) with a hole

Workh

olding

Devices..

Workpiece Mandrel


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Rests

Workh

olding

Devices..

Jaws

HingeWork Work Jaws

Lathe bed guideways

Carriage

Steady Rest Follower Rest


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Operating/Cutting Conditions1. Cutting Speed v

2. Feed f3. Depth of Cut d

Workpiece

Tool

Chip

Tool post

S

peripheral

speed (m/min)

N (rev/min)

D


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Operating Conditions

Workpiece

Tool

Chip

Tool post

S

peripheral

speed

N (rev/min)

D

NDSspeedperipheral

D

rotation1intraveltoolrelative


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Cutting SpeedThe Peripheral Speed of Workpiece past the Cutting Tool

=Cutting SpeedOpera

tingC

onditions..

m/min1000

NDv

D Diameter (mm)N Revolutions per Minute (rpm)


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Feed

f the distance the tool advances for every rotation ofworkpiece (mm/rev)

Opera

tingC

onditions..

f

Feed

DD 21


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Depth of Cut

perpendicular distance between machined surface and uncut

surface of the Workpiece

d= (D1D2)/2 (mm)

Opera

tingC

onditions..

dDepth

of Cut

DD 21


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3 Operating Conditions

Chip

Machined

surface

Workpiece

Depth of cutToolChuck

N

Feed (f )

Cutting speed

Depth of cut (d)


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Selection of ..

Workpiece Material

Tool Material

Tool signature

Surface Finish

Accuracy

Capability of Machine Tool

Opera

tingC

onditions..


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Material Removal Rate

MRRVolume of material removed in one

revolution MRR = Ddf mm3

Job makesN revolutions/min

MRR= DdfN

(mm

3

/min) In terms ofv MRR is given by

MRR= 1000 v d f (mm3/min)Opera

tionsonLathe..


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MRR

dimensional consistency bysubstituting the units

Opera

tionsonLathe..

MRR: DdfN(mm)(mm)(mm/rev)(rev/min)

= mm3/min


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Operations on Lathe

Turning

Facing

knurling

Grooving

Parting

Chamfering

Taper turning

Drilling Threading

Opera

tionsonLathe..


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Turning

Cylindrical job

Opera

tionsonLat

he..


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Turning ..

Cylindrical job

Cutting

speed

Chip

Workpiece

Depth of cut (d)

Depth of cutTool

FeedChuck

N

Machinedsurface

Opera

tionsonLat

he..


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Turning ..

Excess Material is removed

to reduce DiameterCutting Tool: Turning Tool

a depth of cutof 1 mm willreduce diameter by 2 mm

Opera

tionsonLat

he..


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FacingFlat Surface/Reduce length

Depth ofcut

Feed

WorkpieceChuck

Cutting

speed

Tool

d

MachinedFace

Opera

tionsonLat

he..


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Facing ..

machine end of job Flat surfaceor to Reduce Length of Job

Turning Tool

Feed: in direction perpendicular toworkpiece axis

Length of Tool Travel = radius of

workpiece Depth of Cut: in direction parallel to

workpiece axisOpera

tionsonLat

he..


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Facing ..

Opera

tionsonLat

he..


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Eccentric Turning

Axis of job

A

Eccentric peg(to be turned)

4-jawchuck

CuttingspeedO

pera

tionsonLat

he..


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Knurling

Produce rough textured surface

ForDecorative and/orFunctional Purpose Knurling Tool

AFormingProcess

MRR~0

Opera

tionsonLat

he..


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KnurlingOpera

tionsonLat

he..

Knurling toolTool post

Feed

Cutting

speed

Movement

for depth

Knurled surface

K li


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Knurling ..

Opera

tionsonLat

he..


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Grooving

Produces a Groove onworkpiece

Shape of tool shape ofgroove

Carried out using Grooving ToolA form tool

Also called Form TurningOpera

tionsonLat

he..


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Grooving ..Opera

tionsonLat

he..

Shape produced

by form tool Groove

Grooving

toolFeed or

depth of cutForm tool


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Parting

Cutting workpiece into Two

Similar to grooving

Parting Tool

Hogging tool rides overat slow feed

Coolant use

Opera

tions

onLat

he..


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Parting ..

Opera

tions

onLat

he..

FeedParting tool


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Chamfering

Opera

tions

onLat

he..

Chamfering tool

Feed

Chamfer

C


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Chamfering

Beveling sharp machined edges

Similar to form turning

Chamfering tool 45

To

Avoid Sharp Edges Make Assembly Easier

Improve Aesthetics

Opera

tions

onLat

he..

T T i


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Taper Turning

Taper:

CB

A

L

D90

2D1

Opera

tions

onLat

he..

LDD

2tan 21


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Taper Turning..

Methods Form Tool

Swiveling Compound Rest

Taper Turning Attachment Simultaneous Longitudinal and Cross

FeedsOpera

tions

onLathe..

ConicityLDDK 21

Taper Turning


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Taper Turning..By Form Tool

Opera

tions

onLathe..

TaperWorkpiece

Straight

cutting edge

Directionof feed

Form

tool

Taper Turning


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Taper Turning ,,

By Compound Rest

Opera

tions

onLathe..

Face plate

Dog

Tail stock quill

Tail stock

Mandrel

Direction of feed

Compound restSlide

Compound rest

Hand crank

Tool post &

Tool holder

Cross slide

D illi


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Drilling

Drillcutting tool held in TS feed from TS

Opera

tions

onLathe..

Feed

Drill

Quill

clamp movingquill

Tail stock clamp

Tail stock

Documents

Lathe Operation