SHEARING WITH CERAMIC TOOLS .3. DURABILIT Y OF TOOLS

The purpose of this paper is to clear durability of some ceramic tools under heavy load and light load in blanking. HIPed PSZ (partially sta bilized zirconia) and non HIPed PSZ were used as tool materials to bla nk silicon sheets 0.5mm in thickness in order to test the heavy duty w orks. In the initial stage of the blanking, many micro chippings occur e at the edge of the non-HIPed PSZ punch. Then the chipped particles r ub the punch flank near the edge to make many scratch marks. HIPed PSZ punch is not so much chipped and is shown to be more excellent in dur ability than cemented carbide ones. As for blanking under light load, three kinds of ceramic punches made of Si3N4, ZrO2 and ZrO2- (20vol%)A l2O3 were tested and two kinds of punches made of hard metal and cerme t are also used to compare with the above ceramic ones. As a result of blanking of copper alloy sheet 0.25mm in thickness, HIPed PSZ is foun d to be the most suitable materials for blanking punch. The two cerami c punches except the zirconia ones are inferior to the hard metal punc h. The ceramet punch is the worst of all punches in regard to durabili ty.