cenerfuigl casting

Centrifugal casting consists of producing castings by causing molten metal to solidify
in rotating moulds. The speed of the rotation and metal pouring rate vary with the
alloy and size and shape being cast. The following operations include in centrifugal
casting - rotation of mold at a known speed, pouring the molten metal, proper
solidification rate, and extraction of the casting from the mold. The idea of employing
centrifugal force to make castings had been known for a long time, it was A. G.
Eckhardt’s original patent of 1809 which revealed understanding the basic principles
involved. Centrifugal casting has greater reliability than static castings. They are
relatively free from gas and shrinkage porosity. Many times, surface treatments such
as case carburizing, flame hardening and nitriding have to be used when a wear
resistant surface must be combined with a hard tough exterior surface.
One such application is bimetallic pipe consisting of two separate concentric
layers of different alloys/metals bonded together. Such pipes can be economically
used in many applications and can be produced by centrifugal casting process.
Typically, in centrifugal casting, the following structure or zones may occur, Chill
Zone – This layer is of fine equiaxed structure which forms almost instantaneously at
the mould wall, Columnar Zone – This is next to chill zone. It consists of directionally
oriented crystals approx. perpendicular to the mould surface, Equiaxed zone – this
region may occur next to columnar zone characterized by large number of uniformly
grown crystals. Centrifugal casting is suitable for the production of hollow parts, such
as pipes. The process is suited for producing structures with large diameters - pipes
for oil, chemical industry installations and water supply, etc.