The refinery must produce gold bullion, or a gold alloy, depending on the required currency specification. Next, ingots or bars are pressed between rollers to form sheets. Then the metal sheets are wound into coils and, if intended for coins, these sheets are cut into “blanks” in preparation for minting. A gold coin is a coin that is made mostly or entirely of gold.
Most gold coins minted since 1800 are 90 to 92% gold (22 carats), while most current gold bullion coins are pure gold, such as Britannia, Canadian maple leaf and American buffalo. Gold alloyed coins, such as American Gold Eagle and South African Krugerrand, are typically 91.7% gold by weight, and the rest are silver and copper. To manufacture blanks, the Mint buys 1,500 foot long metal coils made to the correct specifications of each denomination. The coil is first fed through a machine that straightens the metal and then into a cutting press.
The die cutting press punches the blanks like a cookie cutter at a speed of 14,000 blanks per minute. They have a slightly different diameter, but the same thickness, as a finished coin. The blanks are transported to the annealing furnace for the next step of the process. The scrap from the coil, called webbing, is crushed and recycled.
The blanks are annealed to prepare them for the hit. Annealing changes the physical properties of the metal to make it softer and allow it to be shaped without breaking. The annealed blanks will better maintain the design during the stroke. Annealing furnace heats blanks to temperatures up to 1600 degrees Fahrenheit in an oxygen-free environment.
Lack of oxygen prevents tarnishing. They are then dropped into a quench tank filled with “slippery” water to quickly lower the temperature. Slippery water is a mixture of water, citric acid powder and lubricants that prevent blanks from sticking together. Steam from the dryer dries the cleaned blanks before they move to the disturbing mill.
Disturbing means “altering the edge of a coin to create a raised edge”. The upsetting mill inserts the blanks into a groove slightly narrower than its diameter. This pushes the metal up around the rim to form a rim. The edge protects the final coin from wear and tear and makes it stackable.
Most of the blanks the Mint buys are ready-to-hit planchets. When the Mint receives a shipment of planchets, inspectors carefully check them to make sure they meet the required specifications. After that, the penny irons go directly to the presses to hit. The planchettes travel to the coin presses to hit the design.
The Mint has several different types of presses, but they all work the same way. The press forces the front and back of the dies together against the planchette to hit both sides of the coin at once. Circulating coin presses use 35 to 100 metric tons of pressure to hit coins, depending on the denomination. Other presses hit with up to 540 tons of force, the pressure used to create America the Beautiful five-ounce silver coins.
The methods used to make coins have evolved over the years. The coins were first made in the ancient kingdom of Lydia more than two thousand years ago. The process of minting old coins was quite simple. First, a small piece of gold, silver or copper was placed in a coin array embedded in a rock-solid surface.
Then, the worker would take a second coin die, place it on top, and hit it with a large hammer. Bullion coins are coins made of precious metals. They are usually minted in weights that are fractions of a troy ounce and are usually made of gold and silver. It is this addition of metals that makes the texture of gold harder, which makes coins more durable.
While modern gold coins are still legal tender, they are not observed in everyday financial transactions, since the value of the metal usually exceeds the face value. Counterfeits of bullion coins (of all kinds) used to be rare and quite easy to spot when comparing their weights, colors and sizes with genuine pieces. Known as the 1-ton gold kangaroo coin with a nominal value of one million dollars, it contains one ton of pure 9999 gold and measures approximately 80 cm in diameter by 12 cm in thickness. While obsolete gold coins are collected mainly for their numismatic value, gold coins today derive their value from the metal content (gold) and, as such, some investors consider them a protection against inflation or a store of value.
This speed is necessary for an operation like the United States Mint, which must produce billions of coins every year. Because coins have the potential to be used as a medium of exchange, it makes sense to make them a little more difficult to ensure that they can withstand movements between users and in transactions. The riddle separates blank coins that do not meet the size or shape requirements of their respective coins. The blanks are then subjected to a chemical bath to remove any oil and dirt that may be on the surface of the coin.
Modern coins are minted with hydraulic minting presses that automatically feed the blanks into the machine. Although “raw” gold or silver coins have not yet been manufactured at this stage, many are exported to some 35 mints around the world. Most gold coins minted since the end of the 19th century have a slightly higher value than the spot price, but many have a much higher value. Robots and automated machines pack numismatic coins in blisters, lenses and other packaging for sale to the public.
This is because the cost of reproducing a given currency may accurately exceed the market value of the originals. . .