Novel extrusion punch design for elimination of punch ejection load and enhanced lubrication

The extreme surface expansion and pressures observed during the backward cup extrusion process can adversely affect the surface of the work-piece and diminish the life of the punches. To reduce or eliminate punch ejection load and galling commonly encountered in the backward extrusion process, a punch system composed of a main body punch and a punch nose insert is proposed. The nose insert is both an elastic strain field generator to facilitate punch removal and a gateway for lubricant transport. The preliminary test results have shown a marked reduction in both galling and the load required to eject the punch.