The Mint’s Fitters and Machinists install the dies in the coin presses. Coin presses can be set up to make different denominations and may make several denominations on the same day. Blanks are fed through the presses, where they are struck on both sides simultaneously by dies. Dies can strike coins with up to 200 tonnes of pressure, at a rate of up to 650 pieces per minute. Under the pressure of striking, metal particles spread and stretch. This results in a sharper rim, and the edge of the coin taking on any serration in the press’ collar. This is how coins get the grooves you often see around their edges.
Coining: Circulating Coins
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