Surface Analysis of Uncoated and PVD Coated Punch at the Hole-Flanging Process

Abstract

This paper researches the surface condition and wear on the hole-flanging punch when producing a flanged Ø7 mm hole in a steel strip S355J2 + N (1.0577) with a thickness of 3 mm. The hole was flanged by a punch with a defined geometry known as a tangent ogive and described via a caliber radius head (CRH) ratio. During the process, wear of the punch made of hardened tool steel 1.3343 appeared after 20,000 strokes. Thus, a multipurpose coating TiCN-MP deposited via Lateral Rotating Arc-Cathode technology was applied on the punch to extend the punch lifetime. The coated punch was polished to remove droplets after deposition process. By applying TiCN-MP coating, 120,000 strokes were applied to reach the same wear as for the uncoated tool steel. The surface of the punch made of the hardened tool steel for uncoated and PVD coated conditions was researched by scanning electron microscopy after wear, and an energy dispersive X-ray (EDX) analysis was done to identify components of bonded material. In addition, the normal pressure on the punch active surface was studied via a numerical simulation of the hole-flanging process. The position of the high normal pressure is well correlated to the position of the adhesive wear for the uncoated and coated punches.

Keywords

• hole-flanging
• punch
• PVD coating
• TiCN-MP
• wear
• normal pressure
• numerical simulation