The dieless punching of ultrasmall-diameter holes was attempted because it is difficult to punch such holes by conventional punching methods. As a result, a hole with a diameter smaller than 6 µm was punched in a 3-µm-thick stainless-steel sheet.
Dieless Blanking using Noncylindrical Micropunches
Piercing holes using noncylindrical micropunches was attempted by dieless blanking. Square and semicircular microholes were successfully pierced in a stainless-steel sheet.