Lincoln Penny Cent Both Sides Blank Planchet Mint Error Coin.

Planchet preparation errors

Mints purchase long strips of metal which are fed through blanking machines that punch out disks known as blank planchets (or simply as planchets or blanks) on which coins are struck. This determines the size and shape of eventual coins.

Blank planchet

The punched disks are first known as "type-1" blanks (or planchets). After an upending mill adds uniform rounded rims, the disks are called "type-2" blanks (or planchets).

Occasionally, Type-1 and Type-2 blanks aren't further processed, ‘escape’ the mint facility and enter circulation. Type-2 blanks may also be considered striking errors as they are prepared correctly, but are released without having been struck.