Method Of holding work

Method of Holding Work

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

Chucks

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

Three-jaw Universal Chuck

• Holds round and hexagonal work• Grasps work quickly and accurate • Three jaws move

simultaneously whenadjusted by chuck Key

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

Collet Chuck• Collet chuck is used to hold small Collet 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

|

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.

Work Held Between Centre

Work Held Between Centres

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.

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

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

Plain Mandrel

Expanding Mandrel

Gang Mandrel

Summary

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