How does one manufacture a congressional gold medal?

U.S. Mint demonstrates the production process
By , Coin World
Published : 05/18/15
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This article complements the cover feature on congressional gold medals that appeared in the June 1, 2015, Monthly issue of Coin World. The video illustrates the actual production of the 9/11 Fallen Heroes congressioial gold medals:

While the U.S. Mint’s engraving staff usually doesn’t begin sculpturing and tooling medal designs until they are officially approved, such was not the case for the gold medal authorized for Israel’s president, Shimon Peres, as the nonagenarian headed into retirement.

The Peres medal was authorized under Public Law 113–114, signed into law June 9, 2014.

The obverse and reverse designs preferred by Peres for his medal were already being readied for production before being presented to the Citizens Coinage Advisory Committee and Commission of Fine Arts for their review and recommendation.

The medal was fast-tracked in preparation for Peres’ Washington, D.C., visit in June 2014 as he headed into retirement.

Peres was presented his medal on June 26, 2014, in the U.S. Capitol Rotunda by the congressional leadership.

The cost to produce the Peres medal was between $25,000 and $30,000, as is the case with most current congressional gold medals. 

The cost of the medal is dependent on the cost of the metal as well as the difficulty in executing the respective designs.

How medals are made

The production process by which congressional gold medals are currently executed is demonstrated here using the Peres medal for illustrations.

Further details provided by the U.S. Mint follow. 

The authorizing legislation determines the number and type of medals to be produced. The die production process and medal production are all executed at the Philadelphia Mint.

Once final obverse and reverse designs are selected by the Treasury secretary or official designee, sculpts are created either digitally or by hand in plaster through successive casting steps.

If the sculpt is made by hand, an additional step is taken to scan the plaster model and convert it into digital 3D data.

Next, the digital models go through an engineering analysis to set height of relief and address detail particulars to promote good metal flow (coinability) without effecting the fidelity of detail in the sculpt.

The final digital 3D models are sent to the CNC (Computerized Numerical Control) department where comprehensive calculations (millions of them) are performed on the complex 3D models to generate the NC cutter paths required to CNC mill the dies.

Finally, 3-inch dies are milled for the obverse and reverse. Milling times range from 24 to 36 hours depending on design complexity.

Only dies are manufactured for the 3-inch congressional gold medals. No hubbing or other tooling is involved.

From start to finish, about two to three weeks of engineering time are generally required to turn around a 3-inch congressional gold medal, including one week to test and strike an approved gold medal.

Depending on the complexity of the design, a sculpt can take an additional two weeks to produce, according to Mint officials.

Machine time equals cost. Additionally, the more complex the design, the higher the tonnages and the greater the number of strikes required to fill the medal, according to U.S. Mint officials.

The U.S. Mint provided the following specifications for the congressional gold medal:

➤ Fineness of the gold = 0.9995 minimum by weight.

➤ Weight of gold of planchets in troy ounces = 19.77 +/- 0.2.

➤ Specific composition (besides the gold in the medal) = P (Phosphorus), Bi (Bismuth), Pb (Lead) 0.0001 by weight maximum.

➤ Edge thickness: The edge thickness of the blank is 0.275 +/- 0.005 inches but the edge thickness of the finished medal will be higher than that. We do not measure finished medals. 

➤ Diameter: After the gold medal is struck the diameter is turned on a lathe and some gold is taken off of the outer diameter. For example, the blank for the Kiowa Tribe Code Talkers congressional gold medal weighed 19.8 troy ounces. After the medal was struck and turned on the lathe, it weighs 14.14 troy ounces, which means that 5.66 troy ounces were lost due to being turned on the lathe.

That metal is subsequently reclaimed.

Public Law 110-420, the Code Talkers Recognition Act of 2008, authorized not only one gold medal for each of the 33 Native American tribes with members to be recognized, but silver versions for Code Talkers still living or their descendants.

Each of the silver medals cost roughly $2765 to produce, according to U.S. Mint officials.

The silver medals are 0.999 fine by weight; silver content is 298.701 grams, or 9.603 troy ounces. Gross weight is 299 grams, plus or minus 9 grams.

Bronze duplicates

The 3-inch and 1.5-inch bronze duplicate medals of the congressional gold medals are a copper alloy. The 3-inch medal is 89 to 91 percent copper, while the 1.5-inch medal is 94 to 96 percent copper.

The balance of the alloy for both sizes of bronzes medals includes lead, iron, phosphorous, zinc, and trace elements.

The 3-inch medals are struck vertically on a Sack and Kiesselback 1,000 ton hydraulic press. The 1.5-inch bronze medals are struck on a Gräbener Press.

For the 3-inch medals, the number of strikes and striking pressure varies depending upon the design. Medals with high relief require more strikes than those with little relief.

Most designs are struck two or three times and at tonnages varying from 400 to 550 tons. For the 1.5-inch medals, they are double struck with an average tonnage of 190 tons.

Traditionally, the obverse is the hammer die and the reverse is the anvil. However, occasionally a design will require the dies to be inverted for better medal flow, to solve metal fill issues, according to Mint officials.

The 3-inch gold medal blanks are provided by the West Point Mint ready to strike. The 3-inch silver blanks are provided by the Sunshine Mint ready to strike.

The 3-inch and 1.5-inch bronze blanks are provided by Olin Brass. The bronze blanks get upset to form raised rims and are burnished prior to striking.

Collectors may find examples of silver and bronze duplicates in major auctions, at major coins shows and on dealer websites.

Current bronze duplicates of the 3-inch gold medals are available in 1.5-inch and 3-inch sizes from the U.S. Mint’s website at http://catalog.usmint.gov/shop/medals/?_ga=1.186880939.2035841651.1400013284. Most of the bills authorizing the gold medals give the Mint authority to strike the collector versions of the medals.

A complete cumulative listing of the medals authorized as well as the recipients can be found at http://history.house.gov/Institution/Gold-Medal/Gold-Medal-Recipients/.

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