Gases for minting money
The Hungarian Mint, a subsidiary of the National Bank of Hungary, has been a customer of Messer for 14 years. Its 70 employees produce Hungary’s coins under conditions of the highest security and, at some time in the future, will probably also mint the Hungarian euro coins. on air spoke to Miklós Sebők, Production Manager at the Mint, about their use of technical gases.
on air: During which phases of striking coins do you use technical gases?
Miklós Sebők: Principally, to harden the iron alloys of our master dies. The structure of the alloy is not strong enough for coins to be struck from it just after it has been mechanically processed. The metal strips from which the coins are struck, receive their imprint, motif and shape by being stamped quickly with the master dies under great pressure. The requisite hardness of the coining die is produced by carefully applying heat treatment in a special oven. One of the elements we use for this is nitrogen.
on air: Could you please explain this to us in more detail?
Miklós Sebők: The coining dies are heated in a vacuum oven, from which the oxygen in the atmosphere has been extracted, and they are heated there to the correct hardening temperature. Finally, the treatment chamber is flooded with pure nitrogen and the master die is cooled very rapidly under great nitrogen pressure, in other words, ‘quenched’. The inert nitrogen not only hardens the steel; it also prevents any unwanted discolouration on the surface.
on air: What advantages are there in using nitrogen?
Miklós Sebők: I can name several. We save time, because the nitrogen treatment does not allow unwanted oxides to form, so we do not have to carry out elaborate surface cleaning. This also improves the quality of the minted coins. The surface of the die remains more consistent than with the old heat treatment process. This improvement of the surface structure of the coins simplifies the subsequent application of the chrome coating. Before we introduced this nitrogen treatment, we were only able to produce between 60,000 and 90,000 coins from one obverse and reverse die set. Now, we can strike three times as many coins with one set. With some types of coin, we can strike up to a million. This saves costs.
on air: Are there further uses for gases in minting coins?
Miklós Sebők: Yes. The metal strips from which the coins are stamped need to be soft-annealed for more effective striking. We use a forming gas, a mixture of nitrogen and hydrogen, for this purpose. This also prevents discolouration of the coins.
on air: What other metals are used in addition to copper?
Miklós Sebők: Originally, coins were almost exclusively made from gold, silver and copper or alternatively bronze. Recently, there has been an increase in the use of other metals such as iron, nickel, zinc, aluminium and chrome in alloys. Copper is an important component in today’s coin alloys because of its anti-bacterial properties. The most common alloy for coins is one of copper and nickel. But now, we are trying to avoid using nickel because of possible allergic reactions. Some euro coins are made from ‘Nordic Gold’. (Editor’s note: an alloy of copper, aluminium, zinc and tin).
on air: What types of coins do you manufacture?
Miklós Sebők: Mostly currency. The Hungarian National Bank commissions us to produce standard and limited-edition coins, to ensure that the required amount of money is in circulation. It is also very important to maintain the more than 1,000-year-old tradition of minting money in Hungary and to preserve Hungarian culture and history through the production of commemorative coins. We also have international contracts for commemorative coins, for example from Cyprus, Slovenia, Thailand and Venezuela.
on air: How would you describe your working relationship with Messer?
Miklós Sebők: Trust in your partner is the key to our joint success. We have established a good relationship over the years. The gases we use, and the technology to go with them, have been developed specifically for our needs, and they function faultlessly. We know that we can rely on regular delivery of our technical gases and that we can contact the staff at Messer at any time.
