What Is a Punching Die?
A punching die is a component of a press die, consisting of a punch and a die that work in tandem. There are various types of punches, such as stamping punches, punching punches, bending punches, and drawing punches, each designed for specific shaping processes.
The die is created to match these precision punches, serving as a receptacle that complements the punch shape. Punch and die pairs are typically sharp and precisely made while drawing and bending punches have smoother dies to facilitate metal sliding under pressure. To withstand the high loads and friction, these surfaces are often mirror-finished (lapping) and surface-treated.
Materials, like die steel, HAP, powdered HSS, and SKD (hardened), are commonly used due to the high loads involved in the punching process.
Uses of Punching Dies
Punching dies are critical components of press dies, used to process steel plates and other materials. They are employed in both single-shot dies for simpler operations and progressive dies for more complex, multi-step processes. Progressive dies combine several punching dies for drilling, engraving, punching, drawing, shearing, etc., enabling efficient mass production.
Principle of Punching Dies
The role of clearance in the punching process is crucial. For example, the die processing dimension should be slightly larger than the punch size to accommodate clearance. This clearance must be uniform around the punch, affecting the finish of the pressed product and the longevity of the punching die.
The clearance setting varies with the material, with stainless steel often requiring 7 to 11% of the plate thickness. Accurate clearance adjustment, often to the nearest 0.01 mm, is vital. For progressive dies, machining accuracy and proper setup are crucial to ensure alignment and avoid clearance issues. Positioning plates in such dies are typically machined with high precision using machining centers or wire cutting, with careful checks for any tilting that could misalign the dies.