COLD METAL FLOW – This is the ability of a metal to be shape formed by an outside force without heating that metal. In coining, the dies are convex shaped (higher in the center that the rim) and when they strike the planchet, metal from the center of that planchet is forced outward in a radial pattern. This action is similar to dropping a pebble into a body of water. The displacement of the water caused by the intrusion of the pebble will cause a wave of water to travel outward from that center.