Impression die forging units in India follow a process that involves the compression of the piece to be worked, by using an impression die or mould. This die contains cavities that restrict the flow of metal within the die during the deformation.
The metal will fill the space within the die cavity as it is plastically compressed into the mould. Closing of the mould completes the deformation; hence, impression die forging is also referred to as closed die forging. The forged metal part will now have the geometric dimensions of the mould, provided a complete filling of the die cavity occurred during the process.
The grain of the metal is also altered by the forcing of the metal to flow into and fill the impressions in the die. At forging units in India, it is always a consideration in the design of impression die forging to create favourable grain structures through controlled material deformation.