1. Casting, new materials and slitting
Production starts at the highly modern continuous casting furnace at the Casting Section. All the raw materials are melted in the furnace and then cast through carbon dies into two strips which are then drawn through a milling machine where the hardened crust of the alloy is scalped and rolled up into 1, 5 ton coils ready for the rolling process.
Traditional copper-based coinage metals such as Cupro Nickel; brass and bronze have long been used in the production of coins and still represent an important selection of materials for this application.
Along with the range of plated coinage materials, the South African Mint offers a range of traditional coinage alloys. These include materials from the Cupro nickel; aluminium bronze; aluminium nickel bronze and brass range of alloys, as well as more exotic alloys aimed at achieving very specific criteria of colour, electromagnetic properties and wear characteristics. These alloys are produced either in-house by the South African Mint in its modern computerized continuous casting furnace, or in conjunction with its local or international supplier network.
The South African Mint recognizes the importance of these alloys as a component in the design of coinage systems and is constantly involved in research work aimed at finding innovative ways of expanding their field of application.
2. Rolling Mills
Coils are rolled on modern computer-controlled breakdown and fine rolling mills to produce strip of the correct thickness. Electronic measuring equipment controls the thickness and produces a product that is within microns of the required thickness. These tolerances are essential in determining the final mass of the product. Automated delivery and removal of materials using automated guided vehicles allow for an uncluttered and safe working environment
3. Blanking
Blank circular discs are punched out of metal strips by means of precision die sets mounted in high-speed blanking presses. Each coin blank is rimmed on the circumference of the blank before it moves on to the Deburring, Electroplating and Coining process.
4. Electroplating
Electroplating is the process of electro-deposition of a specific thickness of coating either copper, nickel or bronze onto sub strait (core) material of either steel or an alloy.
The process of electro-plating coin blanks is an alternative method of producing less expensive blanks while maintaining the visual and technical characteristics of a solid alloy-based coin. Circulation coins in traditional alloys do not undergo the electroplating process and move past the plating plant on conveyor belts to the next process.
5. Annealing and Polishing
During the annealing process, the coin blanks pass through a flat belt furnace which has a protective atmosphere of Nitrogen to prevent oxidization. All coin blanks then go through a process of polishing after heat treatment to remove any minor scratches or imperfections to give them a high-quality surface finish in preparation for the minting process.
6. Coining
The prepared coin blanks are coined on high-speed presses at speeds ranging from 750-850 strokes per minute where the obverse and reverse of the coin are imprinted with the specific insignia of a particular country, both for South Africa and internationally.
Finished coins are continuously subjected to rigorous quality control inspections. Coins in traditional alloys and electroplated coins are minted in this department.
7. Packing
A variety of packaging options are offered by the South African Mint according to the client’s requirements. Once packed the product is thereafter stored in a computer-controlled high-bay store, accessed by automated guided vehicles only. Alternatively, the product is transported to the Dispatch Department where they are shipped off the client.
