Hydrostatic metal extrusion units in India follow a process in which pressurized liquid completely surrounds the billet, except for the area where the die and the billet come in contact. Though the process can be done cold, warm, or hot, the temperature of the process is limited by how stable the fluid being used is. It is also necessary for the process to be carried out in a cylinder that is sealed to contain the hydrostatic medium. The advantages of hydrostatic extrusionare:
The container and the billet do not produce any friction and so the force requirements are considerably reduced. Faster speeds, higher reduction ratios, and lower billet temperatures are a few of the advantages of no friction.
Ductility of materials used can increase with the application of high pressures.
Material follows an even flow.
Large billets can be used and large cross-sections can be extruded.
No billet residue on the container walls is left.
The disadvantages of hydrostatic extrusion are: One end of the billets has to be tapered to match the die entry angle. This helps in forming a seal at the very beginning of the cycle.
The entire billet also needs to be machined to remove any impurities or surface defects.
It can be difficult to contain the fluid under high pressures.