The definition of Punching
It is a forming process that uses a punch press to force a tool, called a punch, through the work piece to make a hole by shearing. Punching is applicable to a wide range of materials including sheet metal, paper, vulcanized fibre and some kinds of plastic sheet. The punch often passes through the work into a die. Normally, the punching equipment consists of two tool parts – one support for the punches and one for the dies. While the punches enter the dies, the material is being shear cut. Punching is usually the most cost effective method for creating holes in sheet materials. The process of a specially shaped punch is used to create multiple usable parts from sheet material is called blanking. In metal forging applications the work is often punched while hot, which is called hot punching. When metal fracture is complete and metal is not removed but stayed in hole, the operation of punching is called slugging.
What is the Process?
A punch and die is usually made of tungsten carbide or hardened steel alloy. A die is located on the opposite side of the work piece and supports the material around the perimeter of the hole and helps to localize the shearing forces for a cleaner edge. There is small amount of clearance between the punch and the die to avoid the punch from sticking in the die and so less force is needed to make the hole. The amount of clearance needed up to the thickness, thicker materials requires more clearance, however the clearance is always less than the thickness of the work piece. The clearance also depends on the hardness of the work piece. The punch press forces the punch through the work piece, producing a hole that has a diameter almost same to the punch, or slightly smaller after the punch is removed. All tough materials stretch to some extent during punching which often make the punch to stick in the work piece. In this case, the punch must be physically pulled back out of the hole while the work is supported from the punch side, and this process is known as stripping. The hole walls will indicate burnished area, rollover, and die break must be often processed further. The slug from the hole falls through the die into container to either dispose or reuse it.
Dongguan JLS Precisoin Mold Parts Co.,Ltd is a professional punch and die tool maker, which made of super hard tungsten carbide (88-92HRA). The punch, also being called as tungsten mold components, precision tungsten punch, and carbide punch, is of extremely tight tolerance, excellent wear resistance, and corrosion resistance.
