NNP

Punch Press.  A press derives its force from a ram moving up and down, delivering a sharp brief blow for shaping, cutting and trimming metalworking procedures. Small objects, less than three-quarters of an inch can be diestruck on a punch press, but generally they do not deliver enough force to strike larger or relief items like coins and medals. Most blanking – of any gauge material, size and shape – is done on punch presses. Also all mechanical trimming, particularly for all medallic work, is done on punch presses (unless the trimming is done by hand). All large presses are power operated, however, some small presses are operated manually, as a kick press, which can blank up to 1/2-inch, or trim up to 1 1/2-inch. Medals with a lug typically are trimmed on such a manual press (the lug is made into a LOOP afterwards). Essentially a knuckle-joint press is a punch press of great power, modified to deliver a squeeze during striking with extrusion dwell (preventing the metal from springing back by molecular memory).  See presses and press room practices.

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators

COMPILED AND WRITTEN BY D. WAYNE JOHNSON