How Coins Are Made

Making a coin is a fascinating process that begins with the production of blanks.
Blanks cut from sheets of metal and are usually round but can come in many different shapes, such as the Australian 50 cent (dodecagonal or 12 sided). This creates the Planchette.

The Planchettes are rolled through a specially-shaped groove, which results in a raised edge or Rim and fed into the coin press where they are struck by dies. 

A coin die is a metal stamping tool that has an inverse design engraved on it. Two dies are needed to strike a coin. One for the Obverse (heads) and the other for the Reverse (tails).

Coin dies are usually made of hardened steel as they need to withstand repeated striking under massive pressure. The design for the Die can be made on a computer using specialised software or  using modelling clay and plaster. The sculpted coin model is then scanned and engraved into a steel Die using a precision engraving machine. 
Coin dies can produce many thousands of coins before they wear out, chip or crack. 
Worn dies produce duller features whilst Chipped Dies can cause a type of error called Cuds. Die Cracks can be much more noticeable. Other errors can be caused by using the wrong Die (Mules), Rotated dies, Double strikes, Broken dies or even the use of the wrong planchet. 
Many of these error coins are rare and valuable such as the 2007 Double Head 5c or 2000 $1 Mule.

Once the dies are inserted into the coin press, blank planchettes are fed into the presses and struck by the dies, the press can strike up to 650 coins per minute. Up to 360 Tonnes of pressure is used to strike the planchette, transferring the engraved images and pushes the excess into the teeth like grooves of the press collar. The end result is new coin with a sharp rim and reeding around the edge.