method of holding work

1. Method Of holding work

2. Method of Holding Work
• There are several method of holding work
piece on the lathe machine. This presentation
looks on a few of them.

3. Chucks

5. Chucks
• Used extensively for holding work for
machining operations
– Work large or unusual shape
• Most commonly used lathe chucks
– Three-jaw universal
– Four-jaw independent
– Collet chuck

6. Three-jaw Universal Chuck
• Holds round and hexagonal work
• Grasps work quickly and accurate
• Three jaws move
simultaneously when
adjusted by chuck Key

7. Four-Jaw Independent Chuck
• Used to hold round, square, hexagonal, and
irregularly shaped workpieces
• Has four jaws
– Each can be adjusted independently by chuck Key
• Jaws can be reversed to hold work by inside
diameter

8. Collet Chuck
• Collet chuck is used to hold smallCollet chuck is used to hold small
workpieces.workpieces.
• Used for high-precision work
• Spring collets available to hold round, square,
or hexagon-shaped workpieces
• Each collet has range of only few thousandths
of an inch over or under size stamped on
collet

10. |
Collet Chuck
Special adapter fitted into taper of headstock
spindle, and hollow draw bar having internal
thread inserted in opposite end of headstock
spindle. It draws collet into tapered adapter
causing collet to tighten on workpiece.

12. Work Held Between Centre

13. Work Held Between Centres

14. Face plate
• A faceplate is the basic workholding accessory
for a lathe. It is a circular metal plate which
fixes to the end of the lathe spindle. The
workpiece is then clamped to the faceplate,
typically using t-nuts in slots in the faceplate,
or less commonly threaded holes in the
faceplate itself.

15. Faceplate
• Used to hold work too large or shaped so
it cannot be held in chuck or between
centers
• Usually equipped with several slots to
permit use of bolts to secure work

16. Mandrel
• Holds internally machined workpiece
between centers so further machining
operations are concentric with bore
• Several types, but most common
– Plain mandrel
– Expanding mandrel
– Gang mandrel
– Stub mandrel

17. Plain Mandrel

18. Expanding Mandrel

19. Gang Mandrel

20. Summary
• The method use is highly based on the:
• Shape of metal
• Length of metal
• Type of operation to perform
• Condition of the workpiece