Currency coins are made of various metals and alloys like bronze, nickel-brass, cupro-nickel (75% copper and 25% nickel), Aluminium Bronze and stainless steel. The mints buy the strips of metal to manufacture the coins. These strips are about 13 inches wide, 1500 feet long. They come rolled in the form of a coil. The coil is fed through a blanking press. Blanking is a process in which pieces are punched and these pieces called ‘blanks’ are used to make coins.
As a next step, blanks are heated in a furnace to soften them. They are made shiny by washing and then drying them. Now the good ones are selected and made to pass through an ‘upsetting’ machine. This machine raises the outer edge of the coin in order to protect the centre design of the coin from wear. As a last step, they go to the stamping press. Here they are stamped with the design or inscriptions.
Every coin is now checked and then bagged by automatic counting machines before getting distributed to the reserve bank.The making of currency coins is completely controlled by the country’s government. In India, coins are made at one of the four Indian government mints – Kolkata, Mumbai, Hyderabad, and Noida. ‘Mint’ is a place where coins are made. Today Indian coins are made within and outside India. Coins are made in Seoul, Ottawa, Birmingham, Mexico and Pretoria.