Temperature changes with die profiles in axisymmetric forward extrusion process

Abstract

Transient heat transfer and temperature change due to varying die opening shapes in a direct extrusion of lead have been numerically investigated and presented. Upper bound method of analysis was used to evaluate the internal heat generation due to plastic deformation and frictional heat at various stages of the extrusion process. At the extrusion die land region, temperature rises with increasing complexity of die openings geometry with I-shaped section, giving the highest temperature rise, followed by T-shaped section, rectangular, circular shaped die openings with square section die opening, giving the least temperature rise for any given extrusion parameter. The die land zone shows increasing temperature rise with increasing friction coefficient, while increasing friction coefficient has no overall effect on the dead metal zone temperature rise. Increasing die land length leads to increasing contact area between the extrudate and the die resulting in increasing frictional power. It is, therefore, seen that die land is one of the critical factors to consider avoiding surface cracking or hot-shortness in extrusion.