When the punch processing to select die gap means the difference between the die gap of the die punch and the die size of the working portion, i.e. when the punch enters the die, the distance between the punch and the die, usually refers to the total clearance. Clearance is an important parameter to use a punch die can not be ignored, the gap is appropriate choice directly affects part quality, dimensional accuracy, punching power and die size life. Size of the gap thickness and mechanical properties shall be determined by punching, the thicker the material, the gap should be greater. After the user presses the purchase of a brand, its use and maintenance level, will have a direct impact on the quality of workpieces and punch life. Precision equipment and the best punch die clearance is an important part of the production control operating costs. So, learn and have some knowledge in this area and applied to practice, to improve efficiency, reduce costs, have a very important role. Press gap refers punch into the lower die, and both sides of the gap. It is the thickness, material and associated stamping process, the gap should be set according to the thickness of the product, usually bilateral tenth gap thickness. If there are glitches are usually too big a gap. Choose the appropriate punch gap, not only to ensure good punching quality, reduce burr and collapse, but also to maintain a flat sheet, effectively preventing the strip, extending the life of punch. By checking stamping waste case, the gap can be determined punch is not suitable. If the gap is too large, the waste will be fracture surface roughness of the surface and less bright. The larger the gap, the angle of the fracture surface and shiny surface is formed, the greater will be the formation of curling and breaking when punching, or even a thin edge protrusions. Conversely, if the gap is too small, the waste will be small angle larger fracture surface and shiny surface. When slotting, nibbling, shearing and other local press, lateral force will make the punch deflection caused by unilateral gap is too small, sometimes scratching over the General Assembly to edge offset lower die, resulting in rapid wear of the upper and lower die. Punch in the best punch of the gap, the fracture surfaces and bright surface waste has the same angle, and overlap each other, it will give the smallest punching power, punching burrs small.