Principle of Sheet Metal Working and Piercing Tools

The product of a die cutting and punch operation is partially finished or semi-finished part or scrap. The process of making hole is termed as piercing and it generates a scrap slug. If the produced blank is helpful, it is called blanking. Cutting of metal strip occur due to the shearing in blanking and piercing operations. The cutting operation of metal strip takes place because of the plastic deformation, shear and break.

Plastic Deformation

Since the punch descends, it touches the work-piece. The downward movement of punch exerts a force on the work-piece material. Plastic deformation begins as soon as the material exceeds elastic deformation. The combination of plastic and elastic deformation results in upper radius band on the scrap strip and a lower radius band on the work-piece.