How coins are made
A coin's rim is raised before it is ever struck, by rolling the blank through a narrowing groove.
- stations
- 6
- things upstream
- 16
- raw sources
- 9
- steps from the ground
- 4
The short version
Mints buy coils of alloyed strip and punch round blanks from them. The blanks are heated to soften them, cleaned, and rolled through an upsetting mill that raises a rim. A press then drives a die into each one inside a steel collar, which prints both faces and the edge in one blow.
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Roll the strip
Metal is assayed, melted, cast into slabs and rolled to exact thickness. Clad coins bond copper-nickel layers to a copper core. The strip is coiled and shipped to the mint.
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Punch out the blanks
A bank of punches drives through the strip into a bedplate with matching holes, cutting discs slightly larger than the finished coin. Screens drop out thin or broken pieces, which go back to be melted.
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Soften and clean
Blanks pass through an annealing furnace and a water quench. Softer metal needs less striking force, which makes the dies last longer. Tumbling in a chemical bath removes discoloration, and hot air dries them.
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Raise the rim
An upsetting mill rolls each blank along a groove that keeps narrowing, which pushes metal up into a rim. The squeeze sizes the blank and work-hardens its edge.
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Strike between the dies
A planchet drops into a hardened steel collar above the lower die, and the upper die comes down. Metal flows into every line of the engraving, and the collar forms the plain or reeded edge.
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Inspect and count
The press operator spot-checks coins, and a sizing screen called a riddler removes any too large or too small. The rest are counted and bagged.
Worth repeating
- Matthew Boulton installed eight steam-driven presses in 1788, each able to strike 70 to 84 coins per minute.
- The Croeseid, issued by King Croesus of Lydia, are credited as the first true gold coins of standardized purity.
- Some medieval coins, called bracteates, were so thin they were struck on only one side.
Back to the ground
Follow every input upstream and coin starts as these 9 raw sources.
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Sources
Cite this page: "How coins are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/coin