Editor's note: This is the second part of a story by Coin World London Correspondent John Andrew about his visit to the Royal Mint Experience, the Mint's new visitor's center with tour. The original story appears in the June 20 issue of Coin World.
Having the idea was one thing, but converting it into a meaningful and interesting attraction was another.
The business of the Royal Mint of course is making money, not running visitor centers, so the Royal Mint partnered with Mather & Co., a design consultancy, and the Continuum Group, the leading operator of cultural visitor attractions in the United Kingdom.
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The tour of the attraction begins with a short introductory film hosted by Dan Snow, the British television presenter, who regularly presents history programs for the BBC. He also hosts similar introductions at other UK attractions such as the Mary Rose, Henry VIII’s warship that sank in 1545.
This was cleverly done with Snow appearing to be walking around stacks of coins and across their surfaces. The diminutive or shrunken Snow walking across the reverse of a coin is etched on my mind whereas his words, while engaging at the time, have vanished into oblivion.
Our friendly guide then led our small group into the first room where we began to learn about how a coin is made and what they are made from. With the increase in metal prices in recent decades “coppers” are no longer struck from bronze (97 percent copper, 2.5 percent zinc and 0.5 percent tin) but from copper-plated steel. And while most of the “silver” is copper-nickel (75 percent copper, 25 percent nickel), since 2012 the United Kingdom’s 10 and 5-penny coins are made from nickel-plated steel.
We learn that the Royal Mint prepares the alloy in its own furnace, which can reach temperatures of 1,450°C. After sampling the molten metal to confirm that the composition is correct, the melt is then poured into a holding furnace. After it has cooled, the metal is rolled into a continuous strip, usually about 16 millimeters thick.
Casting impurities are removed from the surface of the strip with a scalping machine. This removes around 0.5 millimeter of the surface. The strips, now bright and shiny, are then wound into large coils, weighing up to three-tons. Of course, coins are of varying thicknesses, so the strips have to be further rolled, initially with a heavy roller to get to a 3-millimeter thickness, with a further reduction being achieved with a finishing mill until the thickness is of the required specification.
The strips are then fed into a blanking machine so that a blank of the correct diameter is prepared on which to strike the coin’s design. Around 480,000 blanks for 1-penny pieces can be punched from a single coil of steel at a rate of some 8,000 blanks a minute.
However, that is not quite the end of the story. Up to four more processes are required before the coin can be struck. First the blanks are fed into a rimming machine where they bounce around and, as if by magic, a rim appears around the diameters. This aids the stacking of the coins and protects design elements when the coins enter circulation. If plating is required, then this can be undertaken by the mint.
All this rolling and striking hardens the blanks. So as to get the metal into a better state for striking, the blanks are softened by a process known as annealing. The blanks pass along a conveyor belt through an annealing furnace, which operates at temperatures of up to 950°C.
When the blanks emerge from the furnace they are somewhat blemished. They are then cleaned by being placed in rotating drums containing an acid solution and ball bearings. After a final wash and drying they are ready for being transformed into a coin.