Microtexturing into AISI420 Dies for Fine Piercing of Micropatterns into Metallic Sheets

Abstract

Fine piercing of micropatterns into metallic sheets has become an engineering issue in the stamping industries. Plasma nitriding-assisted printing was proposed as a solution for forming a microtextured surface on die materials. AISI420 die material was employed for this plasma printing. First, maskless patterning was used to print two dimensional micropatterns onto a mirror-polished AISI420 stainless steel surface. The unprinted surface area was selectively nitrided; the negative micropattern of the original prints changed to nitrogen supersaturated AISI420 areas. This die surface was dipped into 20% HCl solution for chemical etching. Since the nitrogen supersaturated areas had high corrosion resistance against this etching, only the printed parts were selectively etched, leaving a hardened AISI420 punch head after etching. These selective nitriding characteristics were demonstrated in experiments. A cylindrical punch array with a diameter of 50 mm was fabricated as a punch for piercing microtextures into thin AISI304 stainless steel sheets.