New dimensions of minting
The small Pacific island state of Niue is known among numismatists as publisher of unusual coin creations. The current “coin” is shaped like a sphere and shows a historical map indicating the seven new wonders of the world with crystals.
The renowned Mint of Poland undertook the realisation of this demanding project.
A technical challenge
Thanks to modern software like ArtCAM, the spherical projection of the design and the following laser engraving are not a big problem nowadays. However, imprinting the entire surface of a round body and designing suitable tools required the development of completely new and innovative solutions. It took the experienced experts of the Mint of Poland several approaches to solutions and numerous practical trials to achieve the perfect final result.
Initial minting trials without design made of copper.
Blank made of rough-turned silver. The sphere was made with excess material. The trick was to precisely dimension this material reserve.
Tool with inserted blank
The completed tool consisting of four segments and a pair of coining dies
„We used a press by Sack & Kiesselbach for this project, because we wanted to have the greatest control possible over all parameters of the minting process.“
Siemowit Kalukiewicz, Chief Operating Officer, Mint of Poland
Engineering and skilled precision work bring the desired result
The perfect result is made possible through the precise interaction of tool and press. The spherical coin is produced on an upstroke hobbing press by Sack & Kiesselbach via manual feeding operation. The advantages:
- Precise control of the press stroke.
- The hydraulic press works power-controlled, displacement-controlled and time-controlled and makes control of the entire minting process in the hundredth millimetre range possible.
- Multiple pressing in the closed tool.
- Makes an optimal material flow during the minting process possible.
- High-precision tool.
- The tool segments are closed and supported via hydraulic pre-tension.
The final product was shown on the WORLD MONEY FAIR 2015 and is now on the market.
Your contact for System consultation
Markus Schlein
Managing Director and machine technology
Sack & Kisselbach Maschinenfabrik GmbH
Langster Str. 9
D-40668 Meerbusch (Langst-Kierst)
Tel: +49-2150-75 62 – 0
Fax: +49-2150-75 62 – 100
info@sack-kiesselbach.de
Siemowit Kalukiewicz
COO and Tool technology
Mint of Poland
11, Waliców Str.
PL-00-851 Warsaw
Tel: +48-22-656 42 67
Fax: +48-22-656 40 40
siemowit_kalukiewicz@mennica.com.pl
other technology topics
The indispensable building blocks of every production at Sack & Kiesselbach are VR and AR.
The indispensable building blocks of every production at Sack & Kiesselbach are VR and AR.
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 …