aluminium casting -process

Gravitech –Industrial visit
Aluminium Casting
The process of casting happens at a very high temperature. Aluminium is not in pure form will melting it. Ingots(blocks) are put in the furnace and melt at 750degrees .The furnace is kept hot or blown hot air with blowers.(Slag) Impurities are separated from ingot by adding blocks of Tib .In order to obtain pure form of aluminium. The impurities are kept aside. At the above specified temperature molten liquid is taken and poured into the cast iron mould at one go (which makes it flow evenly and set into desired form/cast).The mould made of cast iron is of two parts when joined you get provision to pour the hot molten liquid. They go through runners to get dispersed evenly into the desired shape of the mould. Within few seconds mould is taken apart and you get the desired aluminium casts. From one mould they produce desired number of casts as per the order placed by the client. The mould is of high precision /accurate measurement. The cast iron mould costs 2 lakh (for high precision/ accuracy).This way they produce enormous number of casts for tractor/machine parts.
Once it is out of the mould the runners are cut off and fined manually. They also use band saw for cutting .The cut off runners are melted and reused for further casting. This way you find any wastage in the process.