The processes involved in producing a coin can be broken down into three different sections: making the blanks, making the dies and striking the coins.
Making the blanks
Depending on the alloy required, the appropriate metals are melted in the necessary proportions in a furnace. The metal is then extracted from the furnace in the form of a continuous strip, which is cut to produce coils weighing up to 2.8 tonnes. The strip is passed through powerful rolling mills to reduce it to the thickness of a coin. Blank discs of metal are then punched from the strip in a blanking press at a rate of up to 10,000 a minute. Rolling metal under great pressure makes it hard so the blanks have to be softened, something which is achieved by heating them in an annealing furnace at up to 950°C.
Making the dies
Once a design has been approved, a plaster model is prepared at several times the diameter of the intended coin. The plaster model is scanned by a ruby-tipped probe which records the design as a digital file on a computer. Guided by this digital file, an engraving machine cuts the design into a piece of steel at the correct size of the coin. Known as a reduction punch, this piece of steel is then used to make the dies which will actually strike the coins.
Striking the coins
For the final stage of the process, the blanks are fed into a coining press containing a pair of dies. Applying a pressure of around 60 tonnes, the dies strike the blanks and turn them into coins at speeds of up to 850 a minute.
= 1 penny coin =
First Issued February 15, 1971
Diameter 20.3mm
Weight 3.56g
Thickness Bronze: 1.52mm. Copper-plated steel: 1.65mm
Composition Bronze (97pc copper, 2.5pc zinc, 0.5pc tin)
= 2 pence coin =
First Issued February 15, 1971
Diameter 25.9mm
Weight 7.12g
Thickness Bronze: 1.85mm. Copper-plated steel: 2.03mm
Composition Bronze (97pc copper, 2.5pc zinc, 0.5pc tin)
= 5 pence coin =
First Issued Smaller version in June 1990.
Diameter 18.0mm
Weight 3.25g
Thickness 1.7mm
Composition Cupro-nickel (75pc copper, 25pc nickel)
= 10 pence coin =
First Issued Smaller version in September 1992.
Diameter (since 1992) 24.5mm
Weight 6.5g
Thickness 1.85mm
Composition Cupro-nickel (75pc copper, 25pc nickel)
= 20 pence coin =
First Issued June 9, 1982
Diameter 21.4mm
Weight 5g
Thickness 1.7mm
Composition Cupro-nickel (84pc copper, 16c nickel)
= 50 pence coin =
First Issued Smaller version introduced in September 1997. Diameter (since 1997) 27.3mm
Weight 8.0g
Thickness 1.78mm
Composition Cupro-nickel (75pc copper, 25pc nickel)
= 1 pound coin =
Issue Date April 21, 1983
Diameter 22.5mm
Weight 9.5g
Thickness 3.15mm
Composition Nickel-Brass (70pc copper, 5.5pc nickel, 24.5pc zinc)
= 2 pound coin =
First Issued June 15, 1998
Diameter 28.4mm
Weight 12g
Thickness 2.5mm
Composition, Outer Nickel-Brass (76pc copper, 4pc nickel, 20pc zinc). Inner Cupro-nickel (75pc copper, 25pc nickel)
= 5 pound coin =
First Issued August 4, 1990. Previously crowns had a face value of 25p
Diameter 38.61mm
Weight 28.28g
Thickness 2.89mm
Composition Cupro-nickel (75pc copper, 25pc nickel)
Collector versions have been struck in precious metals
As an international manufacturer and supplier for copper sheet and bronze sheet, Shanghai Metal Corporation produces slitting, edging, and oscillates winding to fit your specific copper requirements. To find out more, please visit our Website or send your inquiry here. Our English speaking personnel will be more than pleased to help you. Follow us on LinkedIn, Twitter, Facebook, Instagram and don’t forget to subscribe to our YouTube channel. Or you could try our new mobile app by scanning our QR code.
Sources: Royal Mint, The Telegraph, museumvictoria.com.au
William P.//SMC Editor
Read more articles by this author here.
#BuildingValueAcrossTheGlobe
Shanghai Metal Corporation 