A Most Innovative Coin: The German Polymer Ring Climate Zone Series

By Gu Jun (Shanghai), for the Journal of East Asian Numismatics ……
On December 8, 2017, in Karlsruhe, Germany, it was raining outside with the foulest chill in the air. But at the Baden-Wuerttemberg Mint, strong glowing warmth permeated everywhere. Guests from banks, mints, and mint equipment suppliers gathered together to witness the birth of a new German polymer ring coin representing the Subtropical Climate Zone. The first strike ceremony of the second coin in the series of “Climate Zones of the Earth” commemorative coins was being held.

The first polymer coin, “Planet Earth,” was issued on April 14, 2016, in Germany. This is the first time a coin using metal and non-metallic materials together has been launched. This product was developed over eight years by the German Ministry of Finance, the State of Baden-Wuerttemberg Mint, the Bavaria Mint, and several scientific research units. The ring material is a non-metallic macromolecule polymer, and the inner core and outer ring are metal materials (copper and nickel alloy). Data shows that the annular non-metallic material offers a metal-like performance for striking, has stable chemical and electromagnetic properties while having thermoplastic properties at the same time, and can meet the processing and mechanical properties of the coin. This annular non-metallic polymer has both aesthetic and anti-counterfeiting functions, and the color of particles embedded in the material changes with the light. After the product was issued, it was warmly welcomed by coin collectors around the world.

A new subject–the “Climate Zone of the Earth” series–was launched in 2017, using the same material combination model. The first coin of this series is the “Tropical Climate Zone” commemorative coin featuring a red polymer ring. Over the next few years, there will be four coins launched with orange, light green, light blue and purple polymer rings.

At the first strike ceremony, Mr. Klaus Meyer-Steffens, representative for the European Vending Machine Association, talked about the advantages of the new polymer coin in vending machines. The polymer is characterized by its high level of counterfeit protection, for it offers the possibility of integrating overt, covert and latent security features for counterfeit detection. These features make the German polymer coin just as secure as a banknote.

The overt counterfeit feature is its attractive, translucent colored polymer ring, which is also minted in the process and thus exhibits the same relief as the metal. Immediately recognizable to every user, this security feature is virtually impossible to imitate by today’s counterfeiters. It would be easy to add a latent security feature through enriching the polymer ring by nanopigments, which, to name just one of the many possibilities, would become visible only in ultraviolet light.

A realistic application is that polymer coins can be used in ATMs or vending machines to ensure higher security. This extra security would not incur high costs for the vending industry, as existing hardware systems could simply be reprogrammed.

After the insertion of a coin these machines check whether it is genuine or fake. To this end, they use precisely tuned sensors to measure the properties of the coin material. The bi-metallic coin had already provided a higher level of security for vending machines, as it allowed for the testing of two metals. However, since the sensors are extremely finely tuned and therefore cannot process the minimal reactions that occur at the transitional zones where the two metals meet, misinterpretations are made occasionally (this problem was addressed in the working group mentioned above). In eight years of research, to which the Leibnitz Institute at the Rheinisch-Westfälische Technische Hochschule contributed also, a new mintable polymer was developed. This enables the machines to measure the two metals completely separate from each other, which leads to a significantly higher accuracy of measurement.

Schuler, one of the world’s leading makers of coinage equipment, has developed an assembly facility for these commemorative coin blanks. This equipment is similar to a circulation coin striking press, with three improved conveying mechanisms outside the frame, which fill rings, cores and polymers into their respective channels. In turn, the inner core, polymer composite ring, and outer ring are fitted into the finished blanks using computer control, and then the blanks are sent to the striking press where coins are struck to final products. The difficulty of blank assembly equipment lies in how to efficiently and precisely assemble the inner core, polymer ring, and outer ring compound together. Therefore, Schuler’s research and development team has been working closely with the Mint. Success took many years. It is said that an excess of more than 200 tons of force is required to separate the inner core and the polymer ring from the outer ring.

The Managing Director of both the Baden-Wuerttemberg Mint and the Stuttgart Mint, Dr. Peter Huber, is very proud of it saying:

“We are ready for producing it as a circulation coinage. The new technology has now also been field-tested for mass production.”

Assistant Undersecretary Walter Leibold, himself an ardent collector of West German (FRG) coins, added:

“With the ‘Climate Zones of the Earth’ coin series, we have not only an innovative and highly beautiful collector’s product, but also one which is of the highest significance for monetary history. Imagine that in the not-too-distant future the technology that we see here as a feature of collector coins might also be used for circulation coins. Probably not in Germany first, but in one of the many other countries for which our State Mints of Baden-Wuerttemberg produce circulation coins and commemorative coins. We are proud of this enterprise, which is being perceived abroad as an ambassador of Baden-Wuerttemberg’s technological performance.”

After the ceremony, Assistant Undersecretary Walter Leibold set the first assembly machine for the blanks in motion, followed by the minting press for the commemorative coins’ proof version. At the proof press he then struck the initial proof specimen. The second was struck by Klaus Meyer-Steffens and the third by Patrick Niesel, the artist who was responsible for the design of the obverse.

As a matter of fact, the new polymer material coin has already won two international professional awards for technologically most innovative coin. This is a milestone in coinage history.
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