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News from the world of minting technology – Part 1

February 11, 2016 – There are a few set dates in the calendar of the coin technicians: One of the most important ones, established in the last few years, is the Technical Forum which, organized by Dieter Merkle / Schuler Presses and Thomas Hogenkamp / Spaleck, is held every year, Thursday before the opening of the World Money Fair. How successful this event has become is illustrated by the figures. 340 applications reached the team of Barbara Balz this year. Although the Technical Forum has moved to the largest hall available in the Estrel Convention Center, there was only just enough space to accommodate all interested parties.

The attendees enjoyed very interesting presentations that worked like showcases, featuring the latest developments of the various market participants. Everybody was grateful towards the organizers for having cut down the number of lectures and prolonged the breaks a bit. Even so, the agenda was still densely packed and, most of all, substantial!!!

David Fletcher / Cooksongold: Direct Precious Metal 3D Printing

The first speaker was David Fletcher from Cooksongold, a company that belongs to the Heimerle+Meule Group. He presented case studies that his company has conducted on the applicability of 3D Printing for coin blanks.
The result is impressive. Using specifically adapted machinery and gold powder that is specially manufactured for this purpose, a laser is now capable of creating three-dimensional structures. The applied metal powder is melted and fused layer by layer. The generated structures of course have not the restrictions known from the minting process. 3D Printing allows creating highly complex structures in several materials. It is even possible to generate hollow sections. It only takes a computer program but no additional minting tools like a mould or a die.
Even if it is amazing to see how fast a 3D printer is currently working, the technology is still far from being applied in mass minting.
David Fletcher introduced a gold medal on whose blank the design has been generated by laser printing.
If you would like to see in a movie how this is done, please click here. (And turn off the sound. The music is terrible.)

Martin Groves / Royal Canadian Mint: Innovative Colour Applications for Coins

In his presentation, Michael Groves, Director of the Department of Development & Applied Technology of the Royal Canadian Mint summarized how the Royal Canadian Mint, in cooperation with Teca-Print USA, has improved the use of ink on coins.
To this end, not only the colors were improved, but the coin designs were likewise adapted, the surfaces prepared in a special way before the application of color, and the conditions of production and the drying process were optimized.
A good example of the ongoing object research is the popular “Glow in the Dark” series of the Canadians. It features the colored image of a dinosaur. If viewed in the dark, the skeleton of the animal appears. It took much effort and additional research to produce this effect. At the beginning, the phosphorescing color proved useless because the particles it was made of were too big and could not be applied accurately enough to give an exact image of the dinosaur’s skeleton. When made of finely ground particles, the color lost its luminous effect. This was countered by the application of not only one layer of color but several layers although this resulted in excessive scratches on the blank’s surface. It was only when multiple layers of luminescent color were applied and a harder blank was used, which would not be damaged so easily during the application of color, that the technical solution for an innovative coin was born.
How quickly these findings are being further developed were illustrated by two other commemorative coins. For an evening scene with fireflies different dark luminous colors that glow in the dark were developed. And in order to give an impressive image of a thunderstorm a new color with fluorescent particles was produced.
The Royal Canadian Mint has received very positive response from its customers concerning these colored coins. Martin Groves noted that collector coins which are produced with these new technologies are often sold out.

Dr Gerd Wagner / Reischauer: Blanks made by Powder Metallurgy

In his presentation, Dr Gerd Wagner from Reischauer lifted the secret of his innovative blanks that do not come in the usual plain shape but can be produced also in a convex shape, depending on customer requirements.
He introduced the use of powder metallurgy: The circular blanks are not being stamped from a coil but pressed from the finest powder. After sintering, the “new” blank can be minted just as any “ordinary” blank, while exhibiting a whole range of improved characteristics for the minting process.
Blanks produced with powder metallurgy have a much higher ductility. The expert knows ductility (derived from the lat. ducere = to pull, to lead) as the formability of the material before it breaks. The high ductility of the new blanks allows generating a significantly higher relief in the minting process which also needs much less pressure. That the minted piece is as hard as any traditional blank became apparent by measurement comparison with the Vickers Hardness. The hardness is achieved by the additional compaction of the material that is only stopped during minting.

Dr Vishal Agarwal / Jarden Zinc Products: Bi-metal Coins

Jarden Zinc has specialized in the manufacture of blanks according to the ZincSecure™ System. ZincSecure™ System is a blank that is based on zinc, plated either with nickel, copper or bronze. Dr Vishal Agarwal examined how this material can be exploited for bi-metal coins.
He noted that for ZincSecure ™ material the force required to separate the ring from the core is between 160 and 220kg. That exceeds the market expectations by far. He found no signs of corrosion at the core/ring interface. In addition, he referred to the many possibilities to create different electromagnetic signatures with different materials. His conclusion was that ZincSecure™ products can compete with any homogeneous alloy when it comes to producing bi-metal coins.

Ralf Freiberger / Mühlbauer Group: Detection of Counterfeit Coins with Optical Methods and Their Industrial Implementation

Ralf Freiberger gave a very instructive talk about how the combination of different optical methods can greatly increase the chance to detect counterfeits. Already under the program of the previous Technical Forum, Ralf Freiberger had introduced an interesting new development that likewise allows inspecting the edge in one single process step. We reported about this in CoinsWeekly. This time, he showed how this can be combined with other developments, resulting in an almost 100% detection of counterfeits of coins in circulation.
Although there are is a highly effective means for counterfeit detection available to the industry – the electromagnetic signature –, two problems are linked to it. On the one hand, numerous materials for blanks can be legally obtained privately so that counterfeits may well consist of the correct basic substances. On the other hand, depending on the different suppliers, the material of the “genuine” coins also vary, which makes it unreasonable to specify all-too-narrow limits for the electromagnetic signature, for otherwise vending machines would reject too many coins.
This is why Ralf Freiberger still favors the optical method which currently allows inspecting 3,000 coins per minute. The time remains the same regardless if only one component is checked or four different components. If the results from four different inspections, such as edge, rim, relief and field, were to be combined, security could be increased dramatically. It would amount to incredible 99.950%. The failure-rate would only be one coin per 10 million circulation coins. Impressive!

Alexander Aminidis / ACSYS Lasertechnik: New Security Techniques with a laser

Alexander Aminidis likewise focused on security. By way of a real-life example, he intended to illustrate which security features can be implemented in coins with laser technology.
The basis was blanks with a diameter of 40mm and a thickness of 3mm, made of brass with a silver .999 coating. The dies required for the minting consisted of hardened Böhler K455 Steel. They were minted at the Staatliche Münze Baden-Württemberg.
Into the design were incorporated: a labyrinth in finest minting with different heights, micro text, a wide range of optical effects, and different frostings, hence sections with a different polishing, that were all made in one single process. Last but least, a QR Code of only 600 micrometers was integrated that is readable with a smartphone app.
With this coin, ACSYS has shown which unbelievable results can be achieved by state-of-the-art laser systems. Nothing has changed security technology in minting more than the possibilities that can be realized thanks to new software in coining die design and laser technology.

The second part of the presentations held at the Technical Forum of the World Money Fair was published here.

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