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A die is an engraved steel tool used in the coining press to impress a design onto a blank coin. At the Royal Canadian Mint, the production of a collector coin requires extra care in every step of the minting process, including the making of the die.
The selection of an artist's sketch is the first step in making dies of a new coin. Some modifications may be made to improve the detail and overall appearance of the finished coin.
The engraver sculpts a model of the design into a large slab of plaster of Paris. This raised design often lacks intricate details.
An impression of the first plaster model is taken to produce a plaster negative model. Intricate details are added to this second model.
A two-step process produces a model with a hard surface that can withstand the machine-engraving which follows. First, a rubber impression is taken of the plaster negative model. Second, a hard plastic impression (epoxy negative model) is made of the rubber positive model.
The epoxy negative model is mounted at one end of a three-dimensional copying machine. As a tracer follows the contours of the epoxy model, a cutter duplicates the design on a smaller brass plate mounted at the opposite end of the machine.
The design on the brass plate is reduced to coin size when it is engraved onto the end of a steel cylinder. The steel cylinder is then hardened by heat treatment to become the reduction matrix.
The reduction matrix is pressed onto a blank steel cylinder, producing a tool called the master punch. After hardening, the master punch is used to impress a series of specially prepared steel cylinders, which become the coin dies.
In the coining press, the dies come together and impress the designs onto the coin blank held between them. The blanks for the new Canadian $2 coin have an outer ring composed of nickel, and a core made of aluminum bronze.
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