Motion drives, the lathe and pressure working

Metal is worked mainly by cutting and by pressure. In pressure working a large outside force plastically deforms the metal: it changes shape and does not return to the old one – aluminium does this, for example. Methods include rolling, drawing (pulling through a die with a hole to thin it), extrusion (squeezing metal out through a die channel), hot forging, and volume and sheet stamping. Lead is a very soft metal that takes shape easily. Tin, aluminium, copper, zinc and iron can be pressure-worked cold; brittle metals like cast iron cannot. In casting, molten metal is poured into a mould and the item is removed once it solidifies; this suits parts of complex shape.