Digital Communication Essentials: DPCM, DM, and ADM .pptx
9M306.1.ppt
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• On completion of this period you would be
able to understand
- Function of Lathe
- Working principle of lathe
Objectives
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Lathe
Industrial revolution demanded
• More production
• More precision
• Changes in manufacturing process
• Lead to the development of high speed and
Special purpose lathes
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Specifications Of Lathe
Lathe is generally specified by
• Swing
• Distance between head stock and tail stock centre
• Swing denotes the maximum diameter of the work
which can be accommodated on the lathe
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Specifications Of Lathe
• Height of the centers above the lathe bed
• Swing over bed
-Largest diameter of work that can be revolved over
the ways of lathe bed
• Swing over carriage
-Largest diameter of work that can be
accommodated over the carriage
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Specifications Of Lathe
• Swing over the gap of bed
-maximum diameter that can be turned over the gap
of bed
• Maximum job length that may be held between centers
(Head stock and tail stock)
• Diameter of hole through lathe spindle for turning bar
work
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Specifications Of Lathe
• Size of bed
• Range of spindle speeds
• Lead screw diameter and threads
• Motor specifications
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Function Of Lathe
•Lathe is used to remove excess material in
the form of chips by rotating the work piece
against a stationary cutting tool
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Working Principle Of Lathe (contd…)
• It holds the work between two supports called centers
• Chuck or Face plate is also used for holding the work
• Chuck or face plate is mounted on machine spindle
• Cutting tool is held and supported on a tool post
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Working Principle Of Lathe (contd…)
• Movement of the job is rotation about spindle axis
• Tool is fed against the revolving work
• Movement of the tool is either parallel to or at any
inclination to the work axis
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Working Principle Of Lathe (contd…)
• If the tool moves
perpendicular to the axis
of work it produces a flat
surface and is called
facing
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Working Principle Of Lathe (contd…)
• If the tool moves
inclined to the axis it
produces a taper
surface and is called
taper turning.
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Speed lathe
• So named because of high speed of head stock
spindle
• Consists of a simple head stock, tail stock and
tool post
• No gearbox, lead screw and carriage
• Tools are hand operated
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Speed Lathe
• Adjustable slide is provided to support the
cutting tool & carriage
• Different speeds are obtained by cone pulley
• Used for light machining operations
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Engine Lathe
• Also known as geared head lathe
• Main parts are bed, head stock, tail stock,
carriage, lead screw, feed change gear box
• Stepped cone pulley or geared head is used for
varying the speed
• Tail stock is provided to facilitate the work between
centers
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Engine Lathe
• Tail stock also permits the use of drills, taps etc
• Cutting tools are controlled either by hand or
power
• Tools can be fed both in cross and longitudinal
directions with respect to lathe axis
• Carriage feed rod and lead screw are used to
perform threading operations
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Tool Room Lathe
• It is modern engine lathe equipped with
necessary accessories for accurate and
precision work
• Best suited for dies, gauges and small tools
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Special Purpose Lathes
• Some lathes have characteristics that enable
them to do certain works well
• These lathes are meant for specific work which
cannot be done on ordinary lathes
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Special Purpose Lathes
Examples :
– Facing lathe- for end facing of bulky cylindrical jobs
– Duplicate lathe-mass production of identical parts
– Gap lathe-to accommodate Large diameter works
– Screw cutting lathe-mass production of threaded parts
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What Is A Production Lathe?
A production lathe is
• A modification of engine lathe
• To meet production demands
• Suitable for mass / batch production
• To hold / machine complicated jobs
• To keep them in continuous production
lines
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Production Lathes Vs Conventional
Engine Lathes
Production lathes
– Can hold complicated jobs
– Setting times reduced
– Minimize production time
– Component accuracy is more
– One worker can look after more than one
machine at a time
– Have high production rates
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Automatic Lathe
• Intended for quality as well as quantity
• Movement of work and tool are done
automatically
• No participation of operator is required (cycle
repeated automatically)
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Semi - Automatic Lathe
• In semi automatic lathe loading and removal of
work is done by operator
• Other operations are performed automatically
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Capstan And Turret Lathe
• Production lathes
• Used to perform large number of operations
simultaneously
• Used for mass production
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Turret Lathe
• Designed for short continuous runs
• Hexagonal turret replaces the tailstock.The turret is a
tool holder
• On which six tools can be mounted
• Can be rotated about a vertical axis
• Entire unit can be moved longitudinally
• It is mounted on the saddle or carriage on bed ways
• It is provided with indexing mechanism
• Indexing mechanism will rotate the present tool away
and bring another tool in position for next operation
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Turret Lathe
• Facilitate for doing large number of operations on
the job
• Suitable for drilling, countersinking, reaming,
tapping operations
• Saddle bolted to the bed of the lathe
• Also called saddle type lathe
• It is heavier in construction
• Initial cost is considerably higher
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Main Advantages
• Different machining operations
- Drilling
- Reaming
- Boring can be performed in a single setting by a
hexagonal turret
• Considerably reduces tool setting time
• Minimized production time
• Skilled operator not essential
• Large scale production of identical parts
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Capstan lathe
The capstan lathe
• It is small or medium size machine
• Ideal for fast production of small parts
• Carries a hexagonal turret on a ram
• Lighter in construction
• Ram slides longitudinally on saddle
• Relatively short stroke of the tool head
• Automatic indexing
• Usually carries six cutting tools
• Rapid presentation of the tools
