Sand casting greater cost. With a completed mold at the appropriate moisture content, the box containing the sand mold is then positioned for filling with molten metal—typically iron, steel, bronze, brass, aluminium, magnesium alloys, or various pot metal alloys, which often include lead, tin, and zinc. After being filled with liquid metal the box is set aside until the metal is sufficiently cool to be strong. The sand is then removed, revealing a rough casting that, in the case of iron or steel, may still be glowing red. In the case of metals that are significantly heavier than the casting sand, such
Ampco Metal into the production of aluminium bronze alloys as sand castings, forgings and centrifugal castings. The company was renamed "AMPCO METAL" in 1930, by which time it had built itself a reputation as a reliable producer of high quality alloys. The Second World War strongly increased the demand for copper-based alloys and industrial bronzes, especially in the field of aeronautics. By 1944, manufacturing operations had grown from 100 to 2,500 employees, and every American airplane carried AMPCO METAL parts somewhere in its structure—in its engines, landing gear, propellers or airframe. In the marine environment, AMPCO METAL propellers were manufactured for landing