Finishing blanking work is the blanking work used for obtaining a smooth cutting cross-section surface. In the case of finishing blanking work, the clearance is made almost zero. In addition, the cutting edges of punches and dies are rounded so as to delay the generation of facture surfaces, thereby preparing smooth cut end surface.

At the time of blanking work, the cutting edge of the die is rounded as shown in [Fig. 1]. In the case of hole punching work, on the other hand, the cutting edge of the punch is rounded.

Although basically rounding is done at the cutting edge, chamfering is also permissible. It is sufficient if the working force is distributed thereby delaying the generation of fracture surfaces. The key factors here are the clearance and blunting the cutting edge (by rounding or chamfering).

The size of rounding is about 0.2mm to 1.0mm rounding radius. When the rounding increased, although the appearance of fracture surface is delayed and a smooth cut end surface is obtained, but there will be more droop, curve, and burrs. Therefore, it is necessary to limit the rounding (chamfering) of the cutting edge to the minimum required amount. The relationship between rounding of the cutting edge and curve is almost a straight line relationship. When the rounding radius is changed from 0.5mm to 1.0mm, the curvature becomes almost twice larger. The stripping force increases as the rounding radius becomes smaller.