278 Modern Metalworking Copyright Goodheart-Willcox Co., Inc. sticking to the punch. The punch is attached to the ram of the press. The term piercing is sometimes used to describe a g punching operation that punches holes in a material. Refer to Figure 17-7. The material removed by the 7 7 piercing die is scrap. The term piercing can also be used to describe the process of perforating a piece of metal or creating a simple slit in the metal. This type of pierc- ing operation also uses a punch and die, but no metal is lost in the process. Progressive dies are often used in blanking and punching operations. A progressive die has all the cutting and forming dies required to make a com- plete part lined up in proper order in one die. Each stage in making the part cuts a portion of the blank, but leaves small connections so the metal section can be transferred to the next stage, Figure 17-7. 7 7 The main parts of the blanking and punching setup include the punch, die, and stripper plate. The stripper plate prevents the metal being worked from Ram Blanking punch Pilot Stripper Punch holder Material movement Piercing punch Finished work Section removed by piercing die (scrap) Die Metal strip movement through dies Goodheart-Willcox Publisher Figure 17-7. Simple progressive die punching operation. As the internal opening of the part is pierced in one section of the metal strip, the finished part is punched out at another station. The stripper plate prevents the metal from sticking to the punch. LVD Strippit Figure 17-6. CNC turret punch press.