A punch is a hard metal rod with a shaped tip at one end and a blunt butt end at the other that is usually struck by a hammer. A variety of punches are used in engineering, but often the purpose is to form an impression of the tip on a workpiece.

Center

A center punch is typically used as an aid to drilling operations; a drill, when brought into contact with a flat surface, will have a tendency to wander on the surface until it gains sufficient purchase to start cutting a hole. A center punch forms a small dimple in which the tip of the drill (if it is small enough) will fit. When drilling larger holes and the web of the drill is wider than the indentation produced by a center punch, the drilling of a pilot hole is usually needed. A center punch usually has a tip, that when viewed on a profile, has sides at a 90 degree angle to one another.

An automatic center punch operates without the need for a hammer.

Prick

A prick punch, while easily confused with the similar looking center punch, serves an entirely different purpose. A prick punch is primarily used for the purposes of layout. By design it produces a smaller indentation than a center punch, which acts as a useful datum point in layout operations. When layout is complete, the indentation made with a prick punch can be enlarged with a center punch to allow for drilling. A prick punch usually has a tip, that when viewed on a profile, has sides at a 30-60 degree angle to one another.