Hydrostatic extrusion

Hydrostatic extrusion is a drawing method in which a metal billet is forced through a draw-plate by means of a fluid under pressure. This process has the great advantage that friction of the billet on the machinery is completely eliminated, but a number of problems arise when it comes to building an industrial apparatus. One is the tightness problem since the equipment must be able to withstand high pressures, a factor which limits the use of the process. At present the method is chiefly used cold under high pressures: 15 to 20kb. Some attempts are being made to apply it warm or even hot. Various procedures are described in the text attached. Several firms such as Kobe-Steel, A.S.E.A. and Fielding and Platt have designed presses intended exclusively for hydrostatic extrusion. Hydrostatic extrusion has also been carried out hot at the French CEA by adaptation of a system onto a conventional vertical press