The money factory
Behind the scenes at Swissmint
); "Building Swissmint")
Producing minting tools – from the artist's sketch to the finished
die
Every coin originates with an artist's sketch. Using this sketch
as the basis for the coin image, first a plaster model with a diameter of
approximately 20 cm is made. From the silicon negative of this plaster model
a resin model is then cast. This is subsequently clamped in a reducing machine
where a sensor registers the relief of the model and reduces it by copy-milling
to a precise coin-sized metal version. Up to 36 hours may be required for
reproducing all the minutiae of the model in mild steel. The steel die thus
produced is known as an original or reduction die.
); "Gravur Modell")
); "Shrinking machine")
); "Engraver")
The finishing touches are applied by a master engraver, who, with infinite care, meticulously perfects the contours and fillet work. Afterwards, the reduction die is hardened, and during a multi-stage pressing procedure a positive die is produced. During this process, the hardened steel is pressed into mild steel, whereby an exact copy of the coin image is transferred onto the latter. Finally, this positive die is used to produce the actual negative minting dies. After pressing, these are turned into the correct shape, hardened, and chromium-plated to enhance durability. Depending upon the variety of coins being minted, the service life of a pair of minting dies generally suffices for producing up to one million coins.
); "Lowering press")
); "CNC grinding machine")
); "CNC automatic lathe")
); "Foremen embossing")
Blanks manufacture
Most of the requisite properties of minted coins must already be reflected
in the size and weight of the circular minting blanks - also known as planchets
or flans. After the changeover from silver to cupronickel coins in the year
1968, the Federal Mint ceased manufacturing planchets, but now rather orders
finished minting blanks primarily from foreign suppliers of non-ferrous metals.
In the production of blanks, the coinage metals are melted in electric smelting
furnaces. A sample is extracted from the molten mass for the purpose of checking
- and also adjusting if need be - the alloy composition by means of X-ray
fluorescent spectrometer analysis.
The molten metal is cast into ingots, which are then reduced in thickness by being repeatedly passed through large rolling mills until the sheets are of the required dimension. The actual minting blanks are afterwards stamped out of these metal strips. A rimming machine is used to flatten the blanks between a block and a roller, thereby forming a smooth raised edge. This bead or rim is necessary to ensure that there is enough metal around the perimeter of the blanks in order that the edge of the coin can also be embossed or lettered during the subsequent minting process. The edge is intended to protect the coin image from wear. The finished blanks are then delivered to Swissmint in special containers
);)
); "Washers in the container")
Minting and packing circulation coins
Swissmint has six high-performance minting machines which operate with a pressure
of 50 to 200 tonnes. Depending upon the coin, the coining presses mint up
to 600 coins a minute. The obverse, reverse and edge are invariably minted
with a single stroke. Between the upper and lower minting dies there is a
so-called ferrule or steel collar in which the blanks are held, and the diameter
of which corresponds to that of the coins to be struck. The ferrule serves
to retain the perfectly circular shape of the coin and to also prevent the
metal from flowing outwards under the immense pressure of the dies. In the
case of coins with a raised legend on the edge, for instance the 5-franc piece,
a ferrule consisting of three segments is used so that after striking the
coins can be ejected without damage to the edge.
); "Embossing machine")
); "Monetary control of the thickness")
); "Five-dearer in the container")
On state-of-the-art packaging lines, the minted coins are first counted and then packed in rolls of 25 or 50 pieces respectively. Conveyor belts take the rolls to the scales and, once the correct weight has been confirmed, they are packed in collapsible cardboard boxes by an industrial robot. After the filled boxes have been sealed shut with bands, they are weighed once again, labelled and palletised. The entire packaging process is fully automated. At regular intervals, the pallets are collected by the Swiss National Bank, which then undertakes the distribution of the coins into the appropriate channels.
); "Packaging machine")
); "Coins in the safe deposit")
Minting and packing collector's coins
As opposed to circulation coins which are continuously struck in normal quality,
collector's coins are either minted in reduced quantities in brilliant uncirculated
quality, or individually with two strokes for coins in polished plate quality
(also known as proof, PP, or mint gloss). The minting of collector's coins
in normal quality is identical to that of circulation coins. Whereas the blanks
supplied for coins to be minted in normal or brilliant uncirculated qualities
require no further preparation (as is also the case with blanks for circulation
coins), those reserved for proof-quality coins are subjected to a series of
preparatory processes, including annealing, pickling, peen-finishing, washing,
and stain-free drying with the aim of achieving optimum surface quality. In
order to obtain the best possible contrast between the lustre of the field
and the frosted appearance of the relief, the minting dies used for proof
coins are also specially polished.
); "Coinage")
); "Coinage PP control")
Commemorative coins in polished-plate quality are hand-packed first in coin cases and then in elegant cases; those in uncirculated quality are either sealed. The annual circulation coin sets in both proof and brilliant uncirculated qualities are presented in a modern outfit of transparent shell packaging.