The document discusses various lathe operations including centering, turning, facing, chamfering, knurling, forming, grooving, parting off, eccentric turning, drilling, reaming, boring, milling, grinding, tapping, thread cutting, and taper turning. It describes the purpose and process of each operation. For taper turning specifically, it explains methods like using a form tool, tailstock set over, compound rest, and taper turning attachment to machine conical surfaces on cylindrical workpieces.

1. UNIT – 4
LATHE OPERATIONS

2. VARIOUS OPERATIONS
In lathe

3. 1. Centering
• It’s a operation performed on the work piece
both ends.
• Here we make a conical hole on the work pice

4. Turning
• It’s a operation to
reduce the diameter of
the work piece.
• The job is revolving in
chuck or between
centers.
• The right or left hand
tool will perform the
operation

5. Facing
• Facing is the operation
to reduce length of the
work piece
• Here the tool moves
perpendicular to the
lathe axis

6. Chamfering & Knurling
• Chamfering is the process of beveling the
work piece edges. Some times for removing
burrs and sharpness
• Knurling is the process of making impressions
on the surface of the work piece by a special
multi point tool

7. Forming
• It’s a process of making
concave or convex or any
irregular shape on the work
piece by a form tool

8. Grooving
• It’s a process of reducing
diameter of the work
piece
• its also called recessing,
undercutting or necking

9. Parting off
• It’s a process of cutting the
work piece into two halves

10. Eccentric turning
• It’s a process special turning.
• Used in manufacturing of
cam shaft , crank shaft

11. Drilling
• For Making a axial hole
in the work piece , the
drill bit is mounted on
the tail stock as shown
in fig.

12. Reaming
• Its performed on
the drilled hole
for removing
burrs.
• It’s a polishing
process or fine
finishing process

13. Boring
• Its used to
enlarge the dia
of the already
drilled hole
• The tool is
mounted on the
bar.

14. Milling
• The work is mounted
on the compound
rest with clamp . And
the multipoint cutter
is mounted in the
head stock

15. Grinding
• A special
grinding wheel is
mounted parallel
to the lathe bed.
• This kind of
process is used
to make
recessing,
polishing works

16. Tapping
• It’s a process of making
internal threads using a
multi point tool called
Tap.

17. Thread cutting
• To producing helical
groove in the cylindrical
work piece.
• Here the job is held
between the centers and
the tool is automatically
fed longitudinally by
using lock nut and lead
screw arrangement.
• Depend on the pitch to
be cut on the work piece ,
the required speed can
be altered by using
change gears

18. Teeth calculations
If the pitch of the lead screw is 6mm
and the pitch of the work is 2mm
By calculation we found that the
spindle must rote 3 times the speed
of the lead screw

19. Speed reduction
• Its done by using
1. Compound gear train
2. Simple Gear train
We need right hand thread
means lead screw rotate clock
wise direction at time spindle
rotate same direction carriage
move towards headstock. But left
hand thread cutting time lead
screw rotate anticlock wise
direction carriage
move towards tailstock

20. External Thread Cutting
• The job is turned to the require
diameter and its held between the
centers.
• Then the required speed is chosen
by using calculations.
• Now the lead screw is rotated ¼ th
of the spindle speed
• Now the lock nut is engaged for
automatic movement of carriage.
• After one helical cut the the tool is
adjusted to required depth . This is
done for getting the required
shape of thread as required.

21. TAPER TURNING

22. TAPER TURNING
• Its defined as a uniform change in the diameter of the work
piece measured along its length
• It’s a process of making conical surface along the cylindrical
work piece
• D – Larger diameter of the taper
• d - Small diameter of the taper
• L – length of the tapered part
• Α – Half taper Angle
CONICITY , K = (D- d) / L

23. TAPER TURNING METHODS
• Form tool method
• Tail stock set over method
• Compound rest method
• Taper turning attachment method

24. Form tool method
• Its one of the simplest
method of producing small
taper in the work piece.
• The tool is ground to the
required angle.
• Then the tool is fed
perpendicular to the work
piece
• Lot of vibrations to machine
tool & high force required
• Low speed machining, can be
minimized the problem

25. Tail stock set over method
• .

26. Tail stock set over method
• In this the tail stock is off set to some required
angle

27. Tail stock set over method
• This method is employed when the taper angle is less than 8
degree
• Here the work piece is held between the centers and the tail
stock is shifted from the lathe axis by adjusting the screws.
• It’s called as tailstock set-over.
• This kind of method is for long and less tapered jobs.

28. Compound rest Method
• This is for doing steep
and short work pieces.
• Here the compound rest
is tilted up to 45 degree
• This method is used for
producing both internal
and external tapers

29. Taper turning attachment method
This attachment is placed on the rear
bed of the lathe with bracket
This arrangement can swiveled to a
maximum angle of 10 degree on either
side
Guide block connect with rear end of the
cross slide