WORKSHOP TECHNOLOGY-Lathe and operation.

1. Lathe and Lathe Operation
Tribhuvan University
Institute of Engineering (IOE)
Himalaya College of Engineering
Prepared By: Er. Amrit Tiwari
Lecturer
Himalaya College of Engineering
“the mother/father of the entire tool family”.

2. Definition
Lathe is a machine, which removes the metal from a piece of work to the
required shape and size.
Lathe is one of the most important machine tools in the metal working
industry.
A lathe operates on the principle of a rotating workpiece and a fixed cutting
tool.
The cutting tool is feed into the workpiece, which rotates about its own axis,
causing the workpiece to be formed to the desired shape.
 Lathe machine is also known as “the mother/father of the entire tool
family”.

3. Principal Parts of Lathe
Lathe Machine is also known as “Centre Lathe”,
because it has two centers between which the job
can be held and rotated.
The main parts of center lathe are:
 Bed
 Head stock
 Tail stock
 Carriage etc

4. Principal Parts of Lathe

5. 1.Bed:
•It is the base or foundation of lathe.
•It is heavy and single piece
casting made to support other parts.
•Two sets of guide ways are at the top
for carriage and tail stock.
•Outer ways is for carriage and inner
ways is for the tailstock.
•Bed length is one of the specifications of lathe.
Principal Parts of Lathe

6. 2. Headstock:
•Permanently fastened on the inner
ways at the left side of the bed.
•Headstock spindle is hollow cylindrical
shaft supported by bearing, and provides
driving from motor to the holding device.
•A live center and sleeve, a face plate, or chuck can be fitted to the spindle nose to
hold and drive the work.
Principal Parts of Lathe

7. 3. Tailstock
•It is situated at opposite side of headstock,
mounted on the inner guide ways of the
lathe bed.
•It can be locked at any position along the
bed.
•Tailstock spindle is hollow tapered shaft,
that can be used to hold the dead center
or other tools.
•Hand wheel is used to fix the position of the dead center with spindle.
Principal Parts of Lathe

8. 4. Carriage:
•Carriage controls and supports the
cutting tool.
•By its help tool moves away or towards
the headstock.
Principal Parts of Lathe

9. Types of Lathe
 Engine Lathe or center lathe
• It is most common type of lathe and is widely used in workshop.
• The speed of the spindle can be widely varied as desired which is not possible in a
speed lathe.
 Bench Lathe
• Small lathe which can mounted on the work bench
• It is used to make small precision and light jobs.
 Speed lathe
• It is named because of the very high speed of the head stock spindle.
• Consists head stock, a tail stock and tool post. it has no gear box.
• Applicable in wood turning, metal spinning and operations.

10.  Tool room lathe :
• It is similar to an engine lathe, designed for obtaining accuracy.
• It is used for manufacturing precision components, dies, tools, jigs etc. and hence it
is called as tool room lathe.
 Automatic Lathe
• A lathe in which the work piece is automatically fed and removed
without use of an operator.
• It requires very less attention after the setup has been made and the
machine loaded.
Types of Lathe

11. Turret Lathe
• Turret lathe is the adaptation of the engine lathe
where the tail stock is replaced by a turret slide
(cylindrical or hexagonal).
• Tool post of the engine lathe is replaced by a
cross slide which can hold number of tools.
Capstan lathe
• These are similar to turret lathe with the difference that turret is not
fixed but moves on an auxiliary slide. These are used for fast production
of small parts.
Types of Lathe

13. Lathe Operation
Facing :
The tool is fed radially into the
rotating work on one end to create a
flat surface on the end.

14. Turning
Instead of feeding the tool radially , the tool
is fed parallel to axis of workpiece to remove
the material from outside diameter
Lathe Operation

15. Taper turning
Instead of feeding the tool parallel to
the axis of rotation of the work, the tool
is fed at an angle, thus creating a tapered
cylinder or conical shape
Lathe Operation

16. Contour turning
Instead of feeding the tool along a
straight line parallel to the axis of
rotation as in turning, the tool follows
a contour that is other than straight,
thus creating a contoured form in the
turned part
Lathe Operation

17. Form turning
In this operation, sometimes called
forming, the tool has a shape that is
imparted to the work by plunging the
tool radially into the work.
Lathe Operation

18. Chamfering
The cutting edge of the tool is used to
cut an angle on the corner of the
cylinder, forming what is called a
‘‘chamfer”
Lathe Operation

19. Cutoff
The tool is fed radially into the
rotating work at some location along
its length to cut off the end of the part.
This operation is sometimes referred
to as parting
Lathe Operation

20. Threading
A pointed tool is fed linearly across
the outside surface of the rotating
work part in a direction parallel to the
axis of rotation at a large effective feed
rate, thus creating threads in the
cylinder.
Lathe Operation

21. Boring
A single-point tool is fed linearly,
parallel to the axis of rotation, on the
inside diameter of an existing hole in
the part
Lathe Operation

22. Drilling
Drilling can be performed on a lathe
by feeding the drill into the rotating
work along its axis. Reaming can be
performed in a similar way
Lathe Operation

23. Knurling
This is not a machining operation
because it does not involve cutting of
material. Instead, it is a metal forming
operation used to produce a regular
crosshatched pattern in the work
surface.
Lathe Operation

24. How taper turning is performed in workshop?

25. Basic Metal Cutting Theory

26. Tool Angles
Different angle in construction of cutting tool
• Rake Angle
• Clearance angle
• Relief angle
Single point cutting tools

27. Work Holding Devices
• The work holding devices are used to hold and rotate the workpieces along with
the spindle.
• Different work holding devices are used according to the shape, length, diameter
and weight of the workpiece and the location of turning on the work.
• Chucks
• Face plate
• Driving plate
• Catch plate
• Carriers
• Mandrels
• Centers

28. Chucks
Work pieces of short length, large diameter and irregular shapes, which can not be
mounted between centres, are held quickly and rigidly in chuck
• Three jaw universal chuck
• Four jaw independent chuck
• Magnetic chuck
• Collet chuck
Work Holding Devices

29. Work Holding Devices
• Three jaws made to slide at the
same time by an equal amount by
rotating any one of the three
pinions by chuck key
• For holding and rotating regular
shaped workpeice
Three Jaw Universal Chuck

30. Work Holding Devices
• Four jaws, each is moved
independently by rotating
a screw with help of chuck
key.
• Can hold works of irregular
shapes
• Takes more time to set the
work aligned with the lathe
axis
Four Jaw Independent Chuck

31. Work Holding Devices
• Holding power is obtained by the magnetic flux
radiating from the electromagnet placed inside the
chuck
• Work pieces made up of magnetic material only are
held
• Very small, thin and lights works which cannot be
held on ordinary chuck are held in this chuck
Magnetic Chuck

32. Work Holding Devices

33. Work Holding Devices

34. Safety in Lathe Operation
• Wear appropriate safety glasses
• Make sure entanglement hazards are removed (e.g. loose clothing, jewellery, etc.).
Tie back and confine long hair.
• Make sure the lathe has a start/stop button within easy reach of the operator.
• Follow job specifications for the speed, feed and depth of cut for materials being
turned. Make sure all work runs true and centered.
• Secure and clamp the piece being worked.
• Remove chuck wrench immediately after adjusting chuck.

35. • Remove all tools, measuring instruments and other objects from saddle or lathe
bed before starting machine.
• Shut off the power supply to the motor before mounting or removing accessories.
• Stop lathe before taking measurements of any kind.
• Keep working surface clean of scraps, tools and materials.
• Keep floor around lathe clean and free of oil and grease.
Safety in Lathe Operation