The document provides a detailed overview of the components and operations of a centre lathe, used for manufacturing cylindrical shapes from various materials. It covers the essential parts of a lathe, such as the headstock, tailstock, and cutting tools, and explains different operations including parallel turning, facing off, and screw-cutting. Additionally, it highlights the efficiency of CNC lathes in industrial applications for mass production.

1. MANUFACTURING TECHNOLOGY-II
UNIT-II
Presented By
Prof.S.Sathishkumar
Assistant Professor
Department of Mechanical Engineering
Vel Tech (Engineering College)
Avadi-Chennai-62

2. Centre lathe

4. • The Centre Lathe is used to manufacture cylindrical
shapes from a range of materials including; steels and
plastics.
• Components that assemble to make an car engine work
have been made using lathes.
• The Lathe may be operated by people (manual lathes)
or computer controlled lathes (CNC machines) that
have been programmed to carry out a particular task.

5. A basic manual centre lathe
• The lathe is
controlled by a
person turning
handles on the
top slide and
cross slide in
order to make a
part.

6. Lathe Parts
• Lathe bed
 Made from rigid cast Iron
 Accurately machined
slideways
 Slideways guide carriage
& tailstock
 Headstock on upper end
of the lathe bed

7. Lathe parts
• Headstock
 Holds lathe spindle
and gears
 Chuck is fitted to
spindle
 Spindle is hollow for
long bars

8. Lathe parts
• Tailstock
 Can be moved along
slideways
 Can be clamped
in any location
 Inside tapered
to hold drill chuck

9. Lathe parts
• Carriage
 Moves along bed
between tailstock and
headstock
 Saddle – across the
lathe
 Apron – hangs down
in front

10. Lathe parts
• Cross Slide
 Fitted on the Saddle
 Moves cutting tool at
right angles to lathe
bed

11. Lathe parts
• Top Slide
(Compound slide)
 Fitted to top of Cross slide
 Carries toolpost and cutting
tool
 Can rotate to any angle
 Is used to turn tapers

12. Lathe parts
• Feed shaft
 Used to move the
Carriage
automatically
• Lead screw
 Used when screw
cutting on the lathe

13. Lathe Parts
• Three Jaw Chuck
 Self centring
 Holds round and
hexagonal work
 3 jaws are connected
 Jaws are stamped 1,2 & 3
and fitted in order
 Chuck key used to open

14. Lathe parts
• Toolpost
 Fitted on top slide and
carries the cutting tool
or the cutting tool
holder
 Can adjust the height
on some types
 Can carry 4 different
tool holders

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

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

17. Cutting Tool Angle
• Clearance angle
 Ensures only the
cutting edge of the
tool touches the work
 Too much clearance
causes chatter

18. Cutting tool angle
• Rake Angle
 Allows the chip being cut
to flow out
 Changing the rake
changes the power used in
cutting and the heat
generated
 Large rake = soft ductile
materials
 Small rake = hard brittle
materials

19. Cutting tool angle
• Tool bits are held in
holders at an angle of
about 15°

20. Cutting tools
• We can put different shapes on the High
speed tool bits to cut different shapes on the
workpiece

21. Lathe operations
Facing off
Parallel Turning
Parallel Turning

22. Parallel Turning
• The tool moved parallel to
the work and cylindrical
shapes are
formed
• Also known as sliding

23. Parallel Turning
• The student can Parallel turn the work on the
lathe manually or use the automatic traverse
option

24. Facing off
• The tool is moved at
right angles to the
work using the cross
slide
• Flat surfaces are
produced

25. Knurling
• A knurling tool is used to press 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
e.g. Screwdriver

26. Knurling

27. Parting off
• 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.

28. Setting the tool height
• The cutting tool on the
lathe must be set to the
exact centre of the
work-piece
• We use the centre of
the tailstock to guide
us to the correct height

29. Screw-cutting on the lathe
• Lathes are also used to
cut threads in round
bars
• These threads take up
different profiles e.g
iso (60°) ACME etc.
• These threads can be
seen on bench vices,
lathes etc.

30. CNC Lathes

31. • In Industry it is not
efficient or profitable to
make everyday products
by hand.
• On a CNC machine it is
possible to make hundreds
of the same item in a day.
• First a design is drawn
using design software,
then it is processed by the
computer and made using
the CNC machine.
• In industry, CNC
machines can be
extremely large.

32. LATHE OPERATIONS
.
Producing a
Cylindrical Surface
Taper Turning
Producing a Flat Surface

33. Drilling on a Lathe
Parting Off / Under Cutting
Radius Turning Attachment