Still no recommendations for alloy changes for circulating U.S. coins

Mint outlines conclusions from research into alternative compositions
By , Coin World
Published : 07/14/17
Text Size

Subtle design and relief modifications to the Jefferson 5-cent coin would be required to extend die life while striking on planchets composed of a harder alloy, according to conclusions reached in the U.S. Mint’s third biennial report to Congress on alternative compositions for circulating coinages.

According to the report, the changes would be made without compromising the integrity of current designs, including sculptor Felix Schlag’s original reverse.

“The coin striking process is a whole system, no part of which can be changed without impacting another,” according to the report. “The aspects include not only die shape and necessary pressure, but also level of detail, sharpness of transitions, and relief height in the coin’s design; overall curvature of the coins’ faces; and the upsetting process, which preforms the blank’s material to the planchet’s rim.”

Connect with Coin World:  

Sign up for our free eNewsletter
Like us on Facebook  
Follow us on Twitter

The third biennial report was publicly released July 12, seven months after its submission to Congress as required under provisions of The Coin Modernization, Oversight and Continuity Act of 2010, Public Law 111-302.

Previous biennial reports were submitted to Congress in mid-December 2012 and 2014. The 2014 report concluded that, while a compositional alternative exists for the Lincoln cent, the option does not offer significant savings to bring production and related costs below face value.

Pushback blanking

The third biennial report’s research also reveals details about other testing ongoing at the Mint, including on what is called “pushback blanking.” Pushback blanking would change how blanks are produced, with blanking equipment using two punches in opposition to cut blanks from strip instead of the current Mint technique of using a single punch to produce the blanks. Under this proposal, the Mint would receive blanks manufactured by an outside vendor or vendors by this method. In another production change, such blanks would be punched from annealed strip, negating the need to anneal blanks after they are punched out, before they are given an upset proto-rim. 

Currently, the Mint receives coils of an alloy of 75 percent copper and 25 percent nickel, from which it punches 5-cent coin blanks, anneals them in a heating furnace to soften them, and then puts them through an upset mill that forms the proto-rim on the planchet.

The report concludes, “While the Mint found pushback blanking to be technically feasible, it could not verify savings; additional testing will be conducted on a full size pilot die to establish high volume production capability and refine the estimates for internal vs. external annealing of the strip.”

The report adds: “Structured trials were completed with optimized die designs and various rimming profiles on the 5-cent coin. The results show promise and can yield incremental efficiencies in the production of circulating coin and other Mint products.

“The Mint will continue validating these results and next steps include small-scale coining trials to optimize 5-cent design and rim profile followed by production-scale die life testing.”

The Mint’s research and development into coin alloy alternatives was legislatively sparked by production costs for the Lincoln copper-plated zinc cent and Jefferson copper-nickel 5-cent coin reaching more than double the face value of the two denominations.


We examine an unusual example of ‘machine doubling’: Another column in the July 24 Coin World examines a VAM marriage that deserves better.


Research for the third biennial report focused exclusively on the 5-cent coin.

Since the release of the second biennial report in 2014, production costs for circulating coin denominations, which includes metal costs, have dropped significantly.

2014 costs to produce the cent, 5-cent coin, dime and quarter dollar were 1.66 cents, 8.09 cents, 3.91 cents and 8.95 cents, respectively, while 2016 costs were recorded at 1.5 cents, 6.32 cents, 3.08 cents and 7.63 cents, respectively.

Focus on 5-cent coin

Since 2014, the U.S. Mint has conducts testing on five different alloy alternatives, one for the 5-cent, dime and quarter dollar and the remaining four solely for the 5-cent coin:

➤ An 80/20 copper-nickel alloy composed of copper-nickel and manganese for the 5-cent coin, with the material also tested for cladding on the dime and quarter dollar, with the intent to adapt results for the half dollar.

➤ C99750T-M — copper, nickel, mang­anese and zinc, tested for 5-cent coin only.

➤ C77000Y-O — copper, nickel and zinc, tested for 5-cent coin only.

➤ R52 Stainless Steel — Iron, nickel, chrom­ium and carbon, tested for 5-cent coin only.

➤ Nickel-plated CPZ — nickel plated on copper-plated zinc, tested for 5-cent coin only.

Testing of the 80/20 alloy suggests the alloy is a seamless alternative to the current composition for the 5-cent, dime and quarter dollar denominations, with the same electromagnetic signature for use in vending applications.

The C99750T-M option offers a potentially seamless alternative for the 5-cent denomination, but additional testing is required for its possible use as a replacement for the cladding layers on the dime and quarter dollar, according to the third biennial report.

The C99750T-M alloy employs manganese and zinc to offset the higher costs of nickel, while still maintaining the current electromagnetic signature.

The R52 stainless steel and the nickel-plated, copper-plated zinc alternatives were studied as co-circulating options alongside the denominations in their existing compositions.

The R52 stainless steel is an “austenitic steel.” According to Britannica.com, “Austenitic steels, which contain 16 to 26 percent chromium and up to 35 percent nickel, usually have the highest corrosion resistance. They ...  are nonmagnetic.”

While viable for coinage, the R52 stainless steel exhibited a mottled, “orange-peel” effect around the rim caused from what is called “strain hardening,” making the appearance less pleasing aesthetically.

If the R52 stainless steel option was adopted, according to the third biennial report, “there would need to be a two- to three-year transition period to develop internal practices to handle the higher hardness of the material (similar to those for nickel-plated and multi-ply-plated steels) and blank preparation/lubrication. This would also coincide with a similar period for coin acceptors and handlers to make the necessary changes to their installed base of coin acceptors and sorters.”

The nickel-plated, copper-plated zinc composition was not considered a viable alternative for the 5-cent coin. “Although it exhibits a different EMS than plated steels and is easier to coin, wear testing of nickel-plated, copper-plated zinc indicated a failure because of severe edge deformation, which led to a breakdown of the edge plating, exposing the zinc core,” according to the report.

U.S. Mint officials indicate work is being pursued on the development of two other co-circulating alternatives for consideration. “One is a monolithic alternative for application to the 5-cent and the other is a plated construction suitable for application to the 5-cent and 10-cent,” according to the third biennial report. 

You are signed in as:null
No comments yet