Back plate
This plate is also known as thrust plate. This plate is mounted on top of the punch holder. It is made out of medium carbon steel. It is hardened and tempered to 45 to 48 HRC. Punch heads have direct contact with this plate, which will prevent the punch penetration into top plate, which will prevent the punch penetration into top plate during punching operation.
This is one of the most important elements of the tool. It is the cutting element of the tool. Punch gives the hole size and the shape on the component. This is made out of high carbon high chromium material. Punches are hardened and tempered to 58-60HRC. The length of the punch in normal condition is kept up to 60mm. Opposite end of the cutting face is shouldered or tapered to mount on top unit
Die plate
This is most on of the important element of the tool. This is mounted on bottom plate. Die plate is the cutting element of the tool which gives the blank size and shape. This is made out of high carbon high chromium steel material. It is hardened and tempered to 60-62 HRC. Die plate thickness is decided on the basis of stock material being cut.
This plate is also called as stripper plate. In guide plate tool this element is known as guide plate. This plate helps in stripping operation. It not only strips the strip from the punch but the main function of this plate is to guide the punch accurately and maintain the alignment of this plate is to guide the punch accurately and maintains the alignment between punch and die. Hence the plate is made with the same care as die. It is mounted on die plate. It is made out of mild steel. In some cases this guide plate is also made out of tool steel. A channel is milled in the plate, which will guide the stock strip.
Accurately ground sleeves, or guide bushings, engage guide pillars for aligning the top plate with the bottom plate. Most bushings are made of tool steel although they are also available in bronze. Pillars and bushings are assembled by shrink fitting into holes bored in the top plate and the bottom plate. The pillars and bushings are subjected to deep freezing, thereby reducing there diameter. They are then inserted in the top plate and bottom plate and upon warming to room temperature, they expand to provide a tight fit between components.
Each guide bushing is provided with a fitting for lubrication.
Stopper
The stopper shown is a plain cylindrical pin. The pin is mounted in the die block. The function of the stopper is to arrest the movement of the strip when it is fed forward to one pitch length. Various types of stoppers are available.
Guide pillars are precision ground pins which are press tool fitted into accurately bored holes in the bottom plate. They engage guide bushings to align punch and die components with a high degree of closeness and accuracy. Guide pillars for precision die sets are hard chromium plated to provide a high degree of resistance to wear.
