Punching Machine

Punching in metalworking is the process of using a punch press to push a punch through the material and into a die to create a hole in the workpiece. A scrap slug from the hole is deposited into the die in the process. Depending on the material being punched this slug may be recycled and reused or discarded. The hole walls will show burnished area, rollover, and die break and must often be further processed. Punching is often the cheapest method for creating holes in sheet metal in medium to high production. A punch is often made of hardened steel or carbides.

The punch press forces the punch into a workpiece piercing a hole that has a diameter equivalent to the punch. A die is located on the opposite side of the workpiece and supports the edge of the hole created to keep it from deforming during the punch. There is a small amount of clearance between the punch's diameter and the die's. This clearance depends on the workpiece material and various tolerances. The slug from the hole falls through the die into some sort of container to either dispose of the slug or recycle it.

Punching is the most cost effective process of making holes in strip or sheet metal for average to high fabrication. It is able to create multiple shaped holes. Punches and dies are usually fabricated from conventional tool steel or carbides . Creates a burnished region roll-over, and die break on sidewall of the resulting hole. The workpiece is often in the form of a sheet or roll. Materials for the workpiece can vary, commonly being metals and plastics. The punch and die themselves can have a variety of shapes to create an array of different shaped holes in the workpiece. Multiple punches may be used together to create a part in one step.

Punching in plastics fabrication usually refers to the removal of scrap plastic from the desired article. For example, in extrusion blow molding it is common to use punching dies to remove tails, molding flash (scrap plastic) and handle slugs from bottles or other molded containers. In shuttle machinery, the containers are usually trimmed in the machines, and finished containers leave the blow molding machine. Other blow molding equipment, such as rotary wheel machinery, requires the use of downstream trimming. Types of downstream trimming equipment include detabbers for tail removal, rotary or reciprocating punch trimmers, and spin trimmers.