Excitement and relieve filled many South Africans on 23 August 2020 when President Cyril Ramaphosa announced our move to level 2 of the national lockdown as part of the COVID-19 risk adjusted strategy. Much of the exhilaration stemmed from the possibility now of being able to visit family, go to parks and gyms and also travel between provinces among other things. This at a time when the Mint is starting to operate and more colleagues are returning to work brings hope that the year could still end on a positive note.
FROM METAL TO MONEY
We have journeyed together through the history of the South African currency, and seen how our colleagues work to bring design to life, now we’d like to show you how we get from metal to money when making a collectable coin…
CASTING
Production starts at the highly modern continuous casting furnace, where the raw materials are melted in the furnace and then cast through casting dies manufactured from very high-grade graphite. There are separate casting dies for 22ct, 24ct and silver.
The gold that is melted in the crucible is activated by a starter bar which is placed in the die, to which the liquid gold attaches and thus initiates the casting process.
As soon as the correct temperature is reached, the starter bar is withdrawn from the die very slowly, and as it is pulled out, the molten gold flows into the die and solidifies. The metal comes out in one thickness and is then rolled down, the result of which is a drawn bar.
ROLLING
After the casting process, the drawn bar is washed and then rolled on a rolling mill to the correct thickness for the coin that is being minted. On the mill, the drawn bar is passed between two rollers to form a strip. The strip length is increased as the thickness is decreased.
Two operators control this process manually, one placing the strip into the mill and the other removing the strip from the mill. This is done with extreme care to prevent surface contamination as well as to avoid scratches to the strip surface.
When the correct thickness is achieved, the strip is washed and inspected for any surface errors. Once it is inspected, the strip is then ready to be blanked.
BLANKING
During the blanking process, a blanking machine which is fitted with a punch and a cutter according to the specific diameter required, is operated manually by an operator. It is again very important that the strip be handled with extreme care so that the surface is not scratched and it can yield the maximum number of blanks possible.
Once the blanks are cut, they are individually inspected, looking at weight, diameter, and visual acceptance according to the requirements of the required coin to be minted.
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries.
ANNEALING
Only 22ct gold and silver blanks go through this stage which uses an open-ended steel belt furnace, equipped with heating and cooling zones that are protected by a continuous flow of gas, called an annealing furnace. The coin blanks are placed in the annealing furnace to soften them (relieve stress).
After softening, the blanks are placed in a heated acid and water solution for 5 – 10 minutes to eliminate any surface contamination, and their hardness is tested. Thereafter, the blanks are ready to be polished.
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries.
POLISHING
The surface of each blank is then polished to a very high lustre to obtain an exceptional surface finish.
The blanks are packed in a special fixture to separate them from one another to prevent damage. This loaded fixture is then placed in a rotating, multi-sided tumbler, with a special soap and polishing media made of minute stainless steel balls of different shapes, after which the blanks are inspected again for flawless lustre and surface finish.
Should they pass the inspection, they are individually hand-dried (between two towels) and packed in a special tray, and are now ready for the coining process.
COINING
In the coining process the blank is struck with two dies simultaneously, one for the obverse coin face and the other for the reverse coin face.
The coining operator individually selects each blank, and feeds it into the coining press, which contains multi-stroke 200 – 260ton knuckle presses, and a serrated collar which restricts the sideways flow of the material.
The blank is then struck between three and five times, depending on the diameter and detail of the coin being minted. After the coin is struck, the operator removes it and inspects it under a magnifying glass before and placing it on a special storage tray.
Some coins are also encapsulated at this stage. The dies are then cleaned with a special soft cloth to remove any residue from the die faces first before the next blank can be struck. The coins are now ready to be packed according to specific packaging requirements.
Did you know: Circulation coins are struck once under normal pressure and a high rate of speed, as they need to be produced in large quantities in accordance to the demands of a country. Collectable coins in contrast, are usually struck at least twice, under high pressure in order to bring out all of the details in the design as they draw their charm from the immaculate representation of the design, as well as the limited quantities they comes in.
PACKING
Packing is the last phase before a coin is ready to be sold. Also a manual process, packers begin by conducting a final inspection of the coins.
The approved coins are then placed in different packaging created to compliment the coin theme as well as appeal to collectors. Some are even accompanied by value-adding items in the packaging such as medallions or miniature models.
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries.
CHILDREN LEARN BETTER THROUGH DOING
According to the Britannica Kids Encyclopedia, manufacturing is the process of making products, or goods, and the businesses that make products are called manufacturers. Why not turn your young engineers into manufacturers with this fun activity to make a coin back. Simply download, print and watch them have fun ‘manufacturing’ their own product!
Click here to download the coin bank activity…
EVER HEARD ABOUT THE LEGEND OF THE LOST HOARD?
Many treasure and glory hunters alike believe that the hoard of gold hidden in South Africa by former President Paul Kruger to avoid being appropriated by the British during the Second Boer War was removed, however no accurate account has ever been produced of its fate. Next month we tell you more about a hoard of gold in our possession, and how you too can own this very special piece of history…
