Control over quality and costs

The State Mint in Berlin produces bimetal/bicolour collector coins in one single processing step on a TMP by Sack & Kiesselbach.

Coins intended for circulation in collection quality are part of the standard programme of the State Mint in Berlin. When it came to the production of euro coins, the question was: pre-assembled bimetal blanks or assembly and minting in one single processing step? The decision was clear.

Blanks as Ring and Core
Image 1: Blanks as Ring and Core


Minting and assembly in one single processing step has Advantages across the board:

  • Economic use of the equipment
    All processing steps are carried out in one step on one machine. No additional press is used for assembly.
  • Longer operational life of the die
    The softer the blank, the lower the wear and the related costs. Unassembled blanks have a core hardness of about 86 HV30 compared to about 114 HV30 in case of pre-assembled blanks.
  • Better coin image
    The softer the material, the better the flow properties in the coining die. Plus, there is less force required.
  • Perfect blanks
    Separate polishing of ring and core is better and easier technically than polishing pre-assembled blanks. Without a separate pre-assembly process, the risk of resulting impurities or damage is also removed. The blanks remain flawless.
Bimetal magazin on the automatic feeding
Image 2: Bimetal magazin on the automatic feeding with ring and core blanks
Infeed and remove gripper on the coining tool
Image 3: Infeed and remove gripper on the coining tool

A perfect minting result requires the most precise feeding and an optimal tool system

For this task, the table medal press (TMP) by Sack & Kiesselbach was equipped with a special transfer system for bimetal coins.

The automated material feeding is the key to the successful minting and assembly in one single processing step. Ring and core are fed-in separately and precisely placed one into the other by vacuum grippers. This task is far from trivial. For example, based on its weight the ring offers only a small suction surface and requires a high degree of reliability of the system.

„Changing to mining and assembly in one single processing step resulted not only in more economic Efficiency but also led to an improvement in product quality.“

Jürgen Stolz, State Mint Berlin

The table medal press (TMP) is available with various extensions for both standard and bimetal coins and makes flexible production possible. Switching formats only takes about 15 minutes.

Image 4: Magazine for standard round coins


Your contact for system consultation

Markus Schlein
Machine technology

Sack & Kiesselbach
Maschinenfabrik GmbH
Langster Str. 9
D-40668 Meerbusch (Langst-Kierst)

Tel: +49-2150-75 62 - 141
Fax:+49-2150-75 62 - 100