(1) An operation in forging and stamping carried out on presses and hammers to produce a hole or depression in an item by pressing a solid or hollow piercing tool or punch into the item. Piercing may also be used in preparation for subsequent hole expansion or broaching of billets on a mandrel and for preliminary marking of a through hole to be produced by subsequent punching.
(2) An operation performed with dies using a sharp-edged punch to remove the inner burr remaining in stamped objects after marking a through hole on them.
(3) An operation in the production of seamless pipe carried out on presses using a piercing tool or on piercing mills using a mandrel to obtain hollow tubing from ingots or billets.