The distance between the cutting edges of both the punch and the die is referred to as die clearance, and this is one of the most important features when it comes to product quality.
The difference between proper die clearance and insufficient or excessive die clearance is extremely noticeable, so it is vital that you pay great attention so you get it right first time.
When you achieve proper die clearance, there will be minimal rollover deformation and a minimum amount of burr. The hole that is created will be clean and precise, with the top third mirroring the size of the punch and the bottom two thirds measuring the inside diameter of the die.
Insufficient clearance can cause wear and tear on your punch because more tonnage is required and, when it is released, additional stripping force is needed due to the hole gripping the punch. When the fracture lines of the punch and die do not meet, there needs to be a secondary shear on the material in order to successfully create a hole; this can cause a large amount of stress on your punch.
Excessive clearance causes more deformation and damage to the material rather than the tools. Although it can wear down the punch’s edge, material rollover is the major problem, plus burr on the bottom side of the material. This is because the angle between the fracture plane and the burnish zone is a lot greater.
Either way, tool life is significantly reduced if you do not achieve proper die clearance. Trial and error is the best way to learn the ins and outs of metal stamping and how to accomplish the ideal results. Different materials may require different applications, so keep trying out different ways and avoid using new, expensive tools until you figure it out.