Ultra-fine piercing by SiC fiber punch

A new ultra-fine piercing in which SiC fiber was used for a punch was proposed. Many new techniques had to be developed in order to realize the process. Thus the ultra-fine punch which has a flat end and an acute edge was obtained and the center of the punch agreed with that of a die. Three kinds of metals which have various thickness and strengths were pierced. A 17 /spl mu/m thick aluminum foil is a specimen of high aspect ratio and low strength, a 15 /spl mu/m thick beryllium copper is a specimen of high strength and a 8 /spl mu/m stainless steel is hard-to-form material. It was shown by observations of a scanning electron microscopy that every hole is truly round and the sheared surface is smooth.