Stage 1: Plastic deformation

The pressure applied by the punch on the stock material tends to deform it into the die opening when the elastic limit is exceeded and by further loading, a portion of the material will be forced into the die opening in the form of an embossed pad on the lower face of the material and will result in a corresponding depression on its upper face. This stage imparts a radius on the upper edge of the opening in the strip and on the lower edge of the punched out material (blank or slug). This is called the stage of plastic deformation.