Punch Effects of Die Material and Tool Surface Finishing on Crack Width at Pierced Holes in Shearing of Amorphous Electrical Steel Sheets

Amorphous electrical steel sheets were subjected to shearing using a tungsten carbide–cobalt (WC–Co) punch. To suppress crack formation on the surface of the piercing holes, the punch was ion-sharpened and subsequently laser-processed to introduce a nanometer-periodic surface structure. A diamond-like carbon coating was applied to increase surface hardness, and the shearing characteristics were compared.