![]() Why is punch and die clearance important in machinery? Correct punch and die clearance are crucial during the punching operation. Proper clearance produces a hole with approximately the top one third measuring the size of the punch and the bottom two-thirds flaring to the approximate inside diameter of the die. Insufficient clearance will usually result in a secondary shear on the material, producing additional wear on the punch. On the other hand, excessive clearance may produce a large flare as well as a burr on the bottom side of the material. Material “roll-over” may also happen along the top edge of the hole and may result in the punch’s sharp edge to break down quickly. There is no exact science for determining the proper clearance between the punch and die. What may work for one particular type of material may be different for another. Follow the clearance chart below for the best results when punching mild steel. Punching Features It is the cheapest process of making holes in the strip or sheet metal for average to high fabrication. It is a quick process. It is able to create multiple shaped holes. Punches and dies are usually fabricated from conventional tool steel or carbides. It creates a burnished region roll-over, and die break on the sidewall of the resulting hole.
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![]() Punching Process with JLS Punches and Dies Nowadays, Punching is usually the most cost-effective method for creating holes in sheet metal materials from medium to high production volumes. The process when a specially shaped punch is used to create multiple usable parts from a sheet of material is known as blanking. In metal forging applications the work is often punched while hot, and this is called hot punching. Slugging is the punching in which punch is finished as soon as the metal fracture is complete and metal is not removed but still held in the hole. PUNCHING PROCESS Punches and dies are often made of tungsten carbide (tungsten carbide punch and die) or hardened steel. A die is located on the opposite side of the workpiece and supports the material around the perimeter of the hole and helps to localize the shearing forces for a cleaner edge. There is a small amount of clearance between the punch and the die to stop the punch from sticking in the die and so less force is needed to make the hole. The amount of clearance needed depends on the thickness, with thicker materials requiring more clearance, but the clearance is always greater than the thickness of the workpiece. The clearance also depends on the hardness of the workpiece. The punch press forces the punch through a workpiece, producing a hole that has a diameter equivalent to the punch, or slightly smaller after the punch is removed. All ductile materials stretch to some extent during punching which often causes the punch to stick in the workpiece. 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 show burnished area, rollover, and die break and must often be further processed. The slug from the hole falls through the die into some sort of container to either dispose of the slug or recycle it. Dongguan JLS Precision Mold Parts Co., Ltd has been devoted to the manufacturing of customized tungsten carbide punch and die for almost 20 years. Our products have been exported to Japan, Germany, France, United Kingdom, etc. We understand that 100% accuracy, unbeatable service and rapid delivery saves our customers’ time and money. Our toolmakers are highly trained and we utilize the best machine tool technology to produce the best possible tooling for our customers. |
AuthorAbby Zhang Archives
August 2021
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