CASTING PROCESS

          Casting is one of the oldest manufacturing process. Manufacturing of a machine part by heating a metal (or) alloy above it's melting point and pouring the liquid metal/alloy in a cavity approximately of same shape and size as the machine part required is called as "Casting Process". After leaving some time the liquid metal cools and solidifies, it acquires the shape and size of the cavity and resembles the finished product required. The department of the workshop, where the castings are made is called as "Foundry".

The manufacturing of casting requires the following steps:

a) Preparation of a pattern,

b) Preparation of a mould with the help of the pattern, 

c) Melting of metal or alloy in a furnace,

d) Pouring the liquid metal into the mould cavity,

e) Breaking the mould to retrieve the casting,

f) Cleaning the casting and cutting off risers, runners, etc., (This operation is called 'Fettling'), and 

g) Inspection of casting for any flaws.

          Castings are prepared with a large number of metals and alloys, both ferrous and non-ferrous. Grey cast Iron components are very common; Steel castings are stronger and are used for components subjected to higher stresses. Bronze and Brass castings are used on ships and in marine environment, where Ferrous items will be subjected to heavy corrosion. Aluminium and Aluminium-Magnesium castings are used in automobiles. Stainless steel castings are used for making Cutlery items.

          Castings is an economical way of producing components of required shape either in small lots (or) in large lots. However, castings are less strong as compared to wrought components produced by processes such as forging etc., However castings offer the possibility of having slightly improved properties in certain part of the castings by techniques such as use of chill etc., In casting process, very little metal is wasted.