A novel technique of friction and material property measurement by tip test in cold forging

Abstract

Tip test experiments and simulations showed that the relationships between the tip distance, forming load, and shear friction factor were linear for all tested materials of aluminium alloys, steel, and copper. The ratio of the shear friction factor of the workpiece-die interface to that of the workpiece-punch interface was determined to be in the range of 23-60 per cent depending on the material. Also a logarithmic relation between the ratio of these two shear friction factors and the strain-hardening exponent of the material was found in the present investigation. Finally, it was clearly demonstrated that the tip test can be used to determine effectively the material property with decoupling of the friction effect in compression tests.