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WORK HOLDING DEVICES IN

LATHE

By N.PRADEEP RAJ

(12LM17)

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Four jaw chuck or independent chuck

Three jaw chuck or self-centering chuck

Air or hydraulic operated chuck Magnetic chuck

Collet chuck

Combination chuck

Drill chuck

TYPES OF CHUCKS

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As the name indicates this chuck has four jaws for holdingthe work each jaw is independent to move.

Advantages

Any type of work piece can be held easily

High grip is possible as four jaws are employed

Disadvantages

Centering is a little difficult process

Semi skilled labor are required

FOUR JAWS OR INDEPENDENT CHUCK

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THREE JAW CHUCK OR SELF CENTERING

In Three jaws for holding the work piece, and if one jaw ismoved then all the other jaws also move by same distance.

This mechanism is obtained by engaging pinions which

meshes with the teeth cut on the under surface of thechuck. This chuck is also called UNIVERSAL CHUCK

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ADVANTAGES

Centering process is not necessary as all the jaws moves

at a time

Consumes less time for mounting and un mounting the

work piece.

DISADVANTAGES

Grip is not so high as only three jobs are employed

All type of jobs cannot be mounted on these chucks, as

they are useful in machining only axis symmetrical objects

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As the name indicates it is a combination of both three-jaw

chuck and four-jaw chuck. It acts as both self-centering and

independent chuck. This is obtained by engaging a scroll disc

at the backside of jaws.

COMBINATION CHUCK

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MAGNETIC CHUCK

In this chuck magnetic force is used for holding

the work piece.

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ADVANTAGES

Work pieces in which damage due to the jaws of chucks is

not tolerated can be effectively machined by using this chuck

If the work to be held is of very small size and cannot be

hold by the above three chucks then this chuck can be used

DISADVANTAGES

All type of jobs cannot be held

Size of the job affects the efficiency of the holding

All type of materials cannot be held as it works on

magnetic property only magnetic materials can be held.

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This is also called as pneumatic chuck as it is beingoperated by hydraulic or air energy. This chuck holds the work

piece due to the pressure generated in the cylinder.

AIR OR HYDRALIC OPERATED CHUCK

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This type of chuck is used when the work to be held is very

long in size.

COLLET CHUCK

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COLLET CHUCK

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This chuck is used for holding the tool in the drillingmachines. This also plays a role in holding taper shanks

on a lathe for easy machining of the job on which holes

are to be drilled.

Drill chuck

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Rest is a work holding device, which is used to hold the

work piece when the work piece of very long length areto be held. In general when a long piece is to be held it

may have directly held then there arises deflection in the

work piece due its own weight. So to prevent the

deflection in the work piece rests of various types areused. Some of the rests being used are

Rests

1) Steady rest

2) Follower rest

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