High precision for perfect coins
“Coins have to meet high technical standards,” explains Dirk Schellhoff, a materials engineer at Waelzholz in Hagen, Germany, who is responsible for the cold rolled steel strip for coinage. “This is because intricate engravings and shiny coin surfaces can only be produced in high quality if the upstream process chain, including configuring the properties of the cold rolled steel strip, is designed to achieve exactly this.” With its focus on outstanding quality, Waelzholz has established itself as a supplier of steel strip for coinage over the course of many years. Material from Waelzholz is used for Brazilian real coins and European cent coins, among others. For over 20 years, the company's Brazilian site Waelzholz Brasmetal has supplied several thousand tons of steel strip for coinage each year that is used to produce 0.25 real and 1 real coins. And our German production site in Hagen recently supplied steel strip for the production of 2 and 5 euro cent coins.
Steel strip with high dimensional tolerance for efficient stamping processesSteel strip with high dimensional tolerance for efficient stamping processes
The cold rolled steel strip’s flatness and thickness tolerances have a significant impact on the further processing of the coin blank. Deviations can lead to an uneven level of detail in the embossing of the coins, resulting in rejects. As Schellhoff explains, “the mints can only manufacture coins of the required quality with high-precision blanks. Thanks to our precisely configured steel materials, the stamping company doesn’t have to compensate for any tolerances in its coating process. This makes its processes more efficient, which increases its competitiveness.” The permissible thickness tolerances lie at a maximum of 0.025 mm, for example, depending on the coin. Thanks to our extensive expertise and high-performance production facilities, Waelzholz can also manufacture to even tighter tolerances, if required.
Ideal material surface for shiny coins
Cold rolled steel strip for coinage is usually electroplated with copper or nickel during further processing. To ensure that this production step is successful, the surface must be as smooth as possible. For us, this means configuring the roughness properties of the steel strip surface to be as low as possible. “Rough strip surfaces make the coins more matte after being electroplated with copper or nickel. The subsequent coin needs to have perfectly smooth and shiny surfaces, however. Thanks to our many years of expertise, we can precisely adjust the roughness properties to meet specific customer requirements,” explains Schellhoff.
Reliable supply thanks to a redundant, international structure
“One of the relevant special features of this market is project-related orders with short lead times. The central banks, as the ultimate purchasers of the coins, expect perfectly on-time coin production when they place their orders,” reports Frederik Sakuth, who coordinates the worldwide distribution of cold rolled steel strip for coins at the Hagen site. “With our expertise and our redundant production lines at various locations worldwide, we are able to supply identical steel materials with the same high standards of quality from different plants. This means that we are highly flexible and can always deliver, even if a production site is temporarily unable to produce, for example, due to a production stoppage,” explains Sakuth. This flexibility helped, for example, during the coronavirus pandemic, when material could be delivered to customers from different locations. “This supply reliability is a real benefit for our customers,” Sakuth says.