centrifugal casting

CENTRIFUGAL CASTING

Prestented by

Parminder Singh

CSE 1

00413202711

Submitted to

Mr. Jagtar Singh

Deptt of Mechanical Engg

GTBIT,New Delhi

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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 the mould 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.

PREREQIUSTIES Mould Material

Steel Cast Iron Graphite Sand

Rotation Speed of Centrifugal Mould about 1000 rpm

A Centrifugal Casting Machine.

A CENTRIFUGAL CASTING MACHINE

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.

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.

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 metal at 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 low melting point constituents such as eutectic phases and sulphide and oxide inclusions. Various theories explain this, one states vibration is the main cause of banding.

APPLICATIONS OF CENTRIFUGAL CASTING

Pipes for water gas sewage. Bearing Bushes. Cylinder Liners. Piston rings Paper making rollers Clutch Plates. Pulleys.

SOME CENTRIFUGAL CASTINGS

Mould Roller

Mould Cover

Rotameter

Water NozzlesTundish

CENTRIFUGAL CASTING SET UP

POURING OPERATION IN CENTRIFUGAL CASTING

Ladle

Molten steel poured into the tundish

Platinum/Platinum 10%Rhodium thermocouple