Coin Making

Manufacturing of Dies

In stark contrast with most modern computerized production processes, the very first steps involved in the making of coins is entirely reliant on the time-honored skills of master craftsmen for the designing and modeling of the new coins. The die-sinkers at the South African Mint combine their artistic flair in interpreting designs, with the strict discipline that is required in a highly advanced technological environment. The first step in the creation of a master die is the three-dimensional modeling of the design in plasticine that is then refined by being cast in a very fine plaster. An acrylic model that forms the completed artwork is then made and reduced and cut in steel by precision three dimensional reducing machines. The South African Mint also uses computer controlled engraving machines for high volume production items. The cut steel dies become the master dies from which the production dies are reproduced.

Casting, new materials and slitting

A dedicated team, consisting of both management and workers, controls the production process of circulation coins within a computer integrated manufacturing system at the South African Mint. Production starts at the highly modern furnace in the Casting Section where the raw materials are melted down in the furnace and then cast into strips that eventually end up as coils.

Rolling Mill

Coils are rolled on modern computer-controlled rolling mills to produce strip of the correct thickness. Electronic measuring equipment controls the rolling gap and produces a product that is within eleven microns of the required thickness. Such fine tolerances are essential in the determining of the final mass of the product.

The delivery and removal of materials is done by means of automated guided vehicles, which allows for an uncluttered and safe working environment.

Blanking

Blank circular discs are punched out of the coiled metal strips by four high-speed blanking presses that can produce 4000 coin blanks per minute. Should the client require unique edge marking on the coins, it is applied at this stage. Each coin blank is rimmed before going to the blank store where it will be kept, pending the next process.

Electroplating

Circulation coins in traditional alloys are not subject to the electroplating process and therefore move past the plating plant to the next process. Traditional coinage metals such as cupro-nickel, brass and bronze have long been used in the production of coins. The South African Mint is constantly involved in research aimed at finding innovative ways to expand its product range, and the manufacturing of bi-coloured coins by means of the electroplating process is one of the more recent coin product developments by the South African Mint.

Annealing

In an annealing process, heat treatment is used to bring the coin blanks to a state of malleability, ie; they are made less hard, in preparation for the minting process. After heat treatment, all coin blanks are polished to make them tarnish resistant.

Coining and Packing

The prepared coin blanks are coined on one of thirteen high-speed presses, each producing 750 coins per minute, and the finished coins are continuously subjected to rigorous quality control inspections. Coins in traditional alloys, electroplated coins and bi-colour coins are also minted in this department. The final products are packed in accordance with the clients' requirements and are then stored in a computer controlled high-bay store that can be accessed only by automated guided vehicles.