Use of Punch and Die in Forming Processes

When you need to do repetitive hole cutting, we use punching with punching and die tool. In this forming process, a tool that is the punch gets forced through a work piece. The hole is formed through shearing. This is applicable to a variety of material including sheet metal, plastic sheet, vulcanized fiber, and more.

Punching better than jobber drilling

This punch is allowed to pass through work piece into a die. Action of punch pushes scrap slug into hole of die. Jobber drilling does not allow much leeway for efficiency, dimension, and size. Depending on what material we use, we can recycle slug scrap. If we need to drill a large hole, then we must have greater motor power and pre-drilling. If you have a requirement, contact the Industrial Punch Manufacturers in Delhi.

We see three phases in a punch and die process. These are deformation, penetration, and fracture. During deformation, punch gets forced down. When this contacts the surface of work material, it causes it to deform. During the second phase, punch continues its onward path and goes completely through work piece. This causes material to fracture unlike the cutting force present in jobber cutting.

Make sure of the clearance

Due to the huge force that pushes the punch into the die, we must make sure there is enough clearance between the edges of the cutting tool and the die. This must remain at 4-8% of the thickness of the stock that you want to punch holes in. When the clearance is too small, fracture lines pass into each other. This might result in double burnishing and you might have to use a larger force.

When the clearance is huge, there is pinching of metal between cutting edges. So, you will find excess burr on the work piece. Most of the punch presses have a manual operation but in large manufacturing plants, they will be mechanically operated. The most commonly used industrial punches use CNC that is a large computer controlled punch press that is of the rail or turret variety.

Shape affects the punching force

Shape of the Metal Punches and Dies affects the force of punching process. Here you see the use of a revolving turret that helps with the punching process. You see the use of hydraulic as well as pneumatic power in use in CNC machines. One must take care to keep clearance always. This helps because you need less force to punch the material. Also, for thicker material you need more clearance.

Most of the materials used have ductile property. So, they will undergo some stretching during the punching process. One of the advantages of punching is that it is a cost effective process. You can make holes in sheet metal or metal strips for ordinary or high precision work. The process does not take much time. Usually, we make punch and die tool sets from carbides or conventional tools steel.

Another great advantage is that we can create multi shaped holes. We have burnished regions roll over in using punching. At times there is die break on sidewall in the resulting hole.