Milled coinage in 1890. In modern practice in the United States, milling, or a milled edge, can refer to the raised edge on the coin face, applied by a special milling machine after the planchets are cut out and polished. In addition, the reeding of coins of higher value, applied by the collar holding the coin when it is stamped, can be considered part of the milled edge. Milled coinage In numismatics, the term milled coinage (also known as machine-struck coinage) is used to describe coins which are produced by some form of machine, rather than by manually hammering coin blanks between
Sheet metal Sheet metal Sheet metal is metal formed by an industrial process into thin, flat pieces. Sheet metal is one of the fundamental forms used in metalworking and it can be cut and bent into a variety of shapes. Countless everyday objects are fabricated from sheet metal. Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate steel or "structural steel." Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll slitter. In most