The finished American Silver Eagle coin is a masterpiece of art and science – the product of a fascinating series of human and modern technological processes. Here is the story in brief.Learn more at-silver coins.
The American Silver Eagle coin, like other coins minted in the United States, began its life from legislative bills, in this case initiated by Senator McClure and Representative Craig in 1982 and amended by Senator McClure’s ‘Liberty Coin Act’ in 1985 and signed into law by President Reagan in the same year.The point of the legislation was to maximize the return on the sale of strategic stockpiles (Defense National Stockpile) of silver (to help balance the Federal Budget) through the production and sale of silver bullion coins. As the stockpiles were being depleted, as intended by the initial legislation, President Bush signed the ‘Support of American Eagle Silver Bullion Program Act’ in 2002 to extend the coinage program through the purchase of silver on the open market.
Senator McClure’s ‘Liberty Coin Act’ stipulated the parameters of the Silver Eagle, including its size, weight, purity, obverse and reverse designs, inscriptions, and edge finish.
Creating the Relief Designs
Ideas for the design of coins come from politicians, citizens, artists and sculptors alike. Once the objectives and concepts of the design are established by all parties, drawings are made of both sides of the coin, including images and textual inscriptions required by law (‘IN GOD WE TRUST’ and ‘E PLURIBUS UNUM’).The final drawings are approved before sculptors and engravers create and refine their renditions using physical and digital modeling techniques. Physical models used to be made with clay and plaster and digitally scanned into a database for more detailed work. Now, more sophisticated software tools are used to model and finish the designs directly from the original drawings. The obverse relief on the American Silver Eagle was taken from Adolph Weinman’s ‘Walking Liberty’ design. On the reverse side, the ‘heraldic eagle’ relief was created by John Mercanti.
Making the Dies
Once the digitized coin reliefs have been completed, CAM (Computer Aided Manufacturing) software is used to interpret this data and create instructions for CNC (Computer Numerical Control) machine cutters of different and finer diameters that will mill out each relief on the end of a separate steel ‘hub’. The result is an extremely polished and accurate replica of the coin design faces on these ‘master hubs’, one for the obverse and one for the reverse design of the coin. Initially, the master hubs that are fabricated are of larger diameter than the legislated coin dimensions. So, a reducing lathe is used to create a master hub of the correct size.
Because dies wear out after a certain number of impressions, the capability to produce enough dies for mass production is met by a succession of master hub to master die steps. The initial master hub of the final correct size is used to create a ‘master die’. The master hub is first hardened by heat treating, while the die material is softened by annealing. The master hub which has a raised design profile is then pressed into the master die material, creating an infuse impression of the coin face in the master die – and as a result is strengthened through the compression of the press. These master dies are then used to create ‘working hubs’ and the working hubs are in turn used to create ‘working dies’. The process is repeated until enough working dies are created for the total production run of coins. The working dies will be used to ‘strike’ and manufacture the coins from silver blanks.