Work Holding DevicesWork Holding Devices

Presented by:Presented by:

Sagar WankhedeSagar Wankhede

INTRODUCTIONINTRODUCTION

The method of holding the parts to be The method of holding the parts to be machined on the machine so that:machined on the machine so that:

1.1. Parts is correctly orientated Parts is correctly orientated 2.2. Dimension is not distortedDimension is not distorted3.3. Locate part with respect to its datumLocate part with respect to its datum4.4. Proper locating and clamping ensures Proper locating and clamping ensures

repeated products and accuracy.repeated products and accuracy.

ConsiderationConsideration

Clamping considerations:-Clamping considerations:- Excess clamping forces can cause Excess clamping forces can cause

distortiondistortion Clamping force should be in the direction Clamping force should be in the direction

of cutting forceof cutting force Clamping should be designed such that Clamping should be designed such that

the cutting force work against the fixed the cutting force work against the fixed portion of clamp, not the movable portion.portion of clamp, not the movable portion.

Chip disposal:-Chip disposal:- Proper clearance need to be made to Proper clearance need to be made to

ensure chips do build up.ensure chips do build up.

Unloading and loading time:-Unloading and loading time:- Time to clamp and unclamp a w/p can Time to clamp and unclamp a w/p can

reduce the rate of production.reduce the rate of production. Clamp design should minimise the motion Clamp design should minimise the motion

needed to remove part.needed to remove part.

Work Holding devices for milling:Work Holding devices for milling:1.1. ViceVice2.2. Angle plateAngle plate3.3. Direct clamping or fixturesDirect clamping or fixtures4.4. ChuckChuck5.5. Tomb stonesTomb stones

VICEVICEMost commonly used for simple shape Most commonly used for simple shape

machiningmachiningManually, air or hydraulically operatedManually, air or hydraulically operatedMount on table so that it is parallel to its x Mount on table so that it is parallel to its x

and y axisand y axisMovable jaw should not be used as a Movable jaw should not be used as a

datum as it movesdatum as it moves

ANGLE PLATEANGLE PLATEFor work that need to be held at 90For work that need to be held at 90 oo angle angle

to the axisto the axisL shaped cast iron or steel that has L shaped cast iron or steel that has

tapped holes or slots to provide for tapped holes or slots to provide for clamping purposesclamping purposes

Suitable for horizontal machining centreSuitable for horizontal machining centre

CHUCKCHUCK

Three jaw chuck used to hold cylindrical Three jaw chuck used to hold cylindrical workpiece on machine tableworkpiece on machine table

Magnetic and vacuum chucksMagnetic and vacuum chucks Magnetic chucks hold only ferrous metal partsMagnetic chucks hold only ferrous metal parts Vacuum chucks are used to clamp part [ferrous Vacuum chucks are used to clamp part [ferrous

or nonferrous] which must be clamped uniformly.or nonferrous] which must be clamped uniformly.

DIRECT WORK MOUNTINGDIRECT WORK MOUNTING

Used to hold big or having odd shaped Used to hold big or having odd shaped workpiecesworkpieces

Bolted directly to the tableBolted directly to the tableRequired ingenuity and expertiseRequired ingenuity and expertise

FIXTURESFIXTURESUsed in the following cases:Used in the following cases:The stock require some periphery The stock require some periphery

machiningmachiningThe stock is too large to be held by a The stock is too large to be held by a

machine vicemachine viceNot rectangular in shape.Not rectangular in shape.

TOMB STONETOMB STONEAllow multipart to be held on any or all of its Allow multipart to be held on any or all of its

parts.parts.Manual or power clamping can be usedManual or power clamping can be usedHeld on rotating machine pallets so that Held on rotating machine pallets so that

each side could be represented.each side could be represented.Increase productivity.Increase productivity.

THANK YOUTHANK YOU