Saturday, 14 April 2012

What is meant by " Casting " of Metals?


Casting

            Casting is a process of pouring molten metal in a mould. The mould has a cavity having shape of the desired object. The mould is made of material capable to withstand the melting point temperature of the metal. Sand is the most common mould material. However, metal moulds or synthetic moulds are also in use.
            A pattern of aluminium, timber or an alike material is first shaped/made. The pattern has the same shape as that of part to be cast. The size of the pattern may be slightly more to allow for the shrinkage of the metal from liquid state to solid state. This pattern is then used to prepare an appropriate mold cavity in the sand. In this mould, adequate pores are provided for pouring the molten metal. On cooling and solidification of the cast object, the mold is broken and the object is sent for finishing operations.
            Cast-iron can only be cast and this is the only process for making cast iron parts. The other malleable metals like steel, aluminium, copper etc can also be cast and this method is also availed many times for these.

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