The Art of Coin Making - Coin Minting Process
Coin minting can be considered an art form, in as much as collecting
them is. It is actually like making a sculpture, starting from the
conceptualization of the design up to the actual striking process.
It all starts with the development of sketches for the coin design. The
mint
has several sculptors in employ, who create one set of sketches for
each commissioned coin. From this set, the mint will choose and approve
one sketch. Then the sculptor will create a clay model several times
larger than the real coin.
This clay model will serve as the first template for what they call the
“Master Hub”. Plaster will be poured all over this clay model to create
the second template, or the plaster model. By doing this, the plaster
model will bear the reverse or mirror image of the design and
inscriptions on the clay model. This process is repeated several times
until a perfect plaster model is achieved.
A third template is the next step, a rubber mold. To make this, epoxy is
poured into the plaster model, creating an elastic mold. This third
template is attached to a transfer engraver with a stylus at the end
that will trace the epoxy or rubber mold. As the stylus traces the mold,
a ratio bar built in the transfer engraver works to reduce the template
to the desired size for the actual coin. The other end of the transfer
engraver has a carbide tool that receives the actual size and cuts the
template into a steel blank. This steel blank is the “Master Hub”.
Now, the making of the coin dies. Coin dies are created by smoothing and
polishing a heated metal in a computerized lathe. Pressing the master
hub onto this blank coin die will give us the “Master Die”. This now,
will be duplicated as working dies and working hubs, which will be used
in the coin striking process.
A blanking press is used to punch and cut out round disks from a metal
coil, creating the actual coin blanks to be minted. This machine works
at 400 strokes per minute. These blanks undergo further annealing and
pickling process. Annealing is a method heating and cooling metal slowly
to strengthen it. On the other hand, pickling is treating metal with
chemicals.
After these processes, the blanks are sorted out. Imperfect blanks are
taken out. Only the perfect blanks are brought to the coining press for
stamping of the design.
One of the dies is wrapped around with a steel collar in the press,
where the
blank is placed and pushed by air pressure. The reverse die, which is
placed
into the press’ upper arm, is simultaneously forced down onto the
blank.
The force creates the impressions of the design on both sides of the
coin blank.
We now have a newly struck or freshly minted coin! |
