centrifugal casting.pptx

7/30/2019 centrifugal casting.pptx

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CENTRIFUGAL CASTING

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C E N T R I F U G A L

C A S T I N G

In this process molten metal is poured in the mould and allowed to solidify while themould is rotating. Metal is poured into the centre of the mould at its axis of rotation.Due to centrifugal force the liquid metal is thrown out towards the periphery.


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PREREQIUSTIES

Mould Material

Steel

Cast Iron

Graphite

Sand

Rotation Speed of Centrifugal Mould about 1000 rpm

A Centrifugal Casting Machine.


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A CENTRIFUGAL CASTING MACHINE


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PROCEDURE

1) The Mould wall is coated with a refractory ceramic

coating (applying Ceramic Slurry , spinning, dying ,

baking).2) Starting rotation of the mould at a pre determined

speed.

3) Pouring of Molten metal directly into the mould (no

gating system is employed).4) The mould is stopped after the casting has been

solidified.

5) Extraction of the casting from the mould.


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CHARACTERISTICS OF CENTRIFUGAL CASTING

1) The casting is relatively free from defects.2) Non metallic impurities which segregate toward the bore can be machined off.3) Less loss of metal in tundish compared to that in gating and risering in

conventional and sand casting.

4) Better mechanical properties.5) Production rate is high.6) Can be employed to manufacture bimetallic pipes.7) Centrifugal casting process can be used for fabricating functionally gradient

metal matrix composite material.


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DEFECTS IN THE CENTRIFUGAL CASTING

Conventional static casting defects like internal shrinkage, gas porosity

and nonmetallic inclusions are less likely to occur in centrifugal casting.

Hot Tears Hot tears are developed in centrifugal castings for which

the highest rotation speeds are used. Longitudinal tears occur when

contraction of casting combined with the expansion of the mould,

generates hoop stresses exceeding the cohesive strength of the metalat temperatures in the solidus region.

Segregation - Centrifugal castings are under various forms of

segregation thus pushing less dense constituents at centre.

Banding

Sometimes castings produce zones of segregated lowmelting point constituents such as eutectic phases and sulphide and

oxide inclusions. Various theories explain this, one states vibration is

the main cause of banding.


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APPLICATIONS OFCENTRIFUGAL CASTING

Pipes for water gas sewage.

Bearing Bushes.

Cylinder Liners.

Piston rings

Paper making rollers

Clutch Plates. Pulleys.


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SOME CENTRIFUGAL CASTINGS


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Mould Roller

Mould

Cover

Rotameter

Water NozzlesTundish

CENTRIFUGAL CASTING SET UP


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POURING OPERATION IN CENTRIFUGAL CASTING

Ladle

Molten steel poured

into the tundish

Platinum/

Platinum 10%

Rhodium

thermocouple


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centrifugal casting.pptx

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