Limiting aspects of the extrusion-machining process (hydrospin)

Abstract A process combining extrusion and machining called Hydrospin, introduced in 1971, is capable of producing fine wire from large billets in one operation, thus eliminating the need for the number of passes encountered in wire drawing. The billet is first hydrostatically extruded to a short tube. This tube of metal is then cut and conventionally extruded through a rotating die—thereby producing wire. The different stages of the process need to be analyzed to determine the correlation among the process parameters and the optimum operating conditions. For this purpose a simple theory highlighting the limitations of the process is presented in this paper. This includes the possible modes of deformation of the process, limit on the final extrusion ratio and the conditions for maximum yield of wire. Tests with a Hydrospin machine indicate that, provided the limits are not exceeded in the design of the dies for the process, optimum operating conditions can be achieved.