Method and apparatus for punching particle board

摘要

A punch and backer plate combination is disclosed as an example of the present invention. The punch has a concave recess in its extended end. The punch may be round or have a rectangular shape in plan view and includes a backer plate having an aligned opening with a similar shape to the punch plus a clearance dimension. The aligned opening of the backer plate includes an upper portion and a lower portion, where the lower portion is enlarged in comparison to the upper portion to allow relief for a slug of material from the workpiece. The punch recess allows stress to be relieved upwardly instead of causing side stresses which induce breaks and cracks in the workpiece.