Error coins add an extra dimension to the enjoyable hobby of coin collecting. Even though the mints thoroughly examine coins before putting them into circulation, examples of production errors sometimes escape without notice. There are several different types of errors that can occur during the minting process, and they can be found on a variety of coins.
A multiple strike error features two or more design strikes on the same coin. This can happen when a coin does not eject properly after being struck and remains in the pressing machine. The dies strike it again, imprinting multiple images on the same coin.
An off-centre strike occurs when a blank coin planchet lands improperly between the upper and lower dies. The dies strike only part of the planchet, resulting in an incomplete design on the coin. This is one of the most common types of minting errors.
These error coins contain no design at all. Blank planchet coins run through the presses at the mint but are not struck. There are two types of blank planchet errors. A Type 1 is flat and comes straight from the blanking press. A type 2 features slightly raised edges, indicating that it has gone through the softening process at the mint.
Clipped planchet coins feature a missing section that has been cut off. The error originates in a shifting of the metal sheet from which the coins are cut. This shift causes the blanks to overlap during the stamping process.
As a coin is struck, a collar holds the planchet in position and adds the design on the outer areas of the coin. If the coin fails to sit firmly in the collar when the dies strike, the edges of the coin will distort and spread into a bowl-like pattern.
Double Die Lincoln Cent
At the U.S. Mint in 1955, a misalignment of the dies occurred during production of the Lincoln cents. This error coin features a doubling effect on the lettering and numbers. It's one of the most famous error coins in United States history.