My Science School

Look at the metal objects around you — perhaps you can see a bicycle wheel, a key or a spoon. Each of these objects has its own special shape. Many metals may appear so hard and strong that it seems impossible to change their form. Powerful machinery, made of even stronger metals, can shape and bend many metals.

When metals are purified they are made into blocks or slabs. The metal can then be shaped to make the many different objects we use. Some metals, such as copper and gold, can be shaped while they are cold. But others, like steel, are more easily shaped when they are red hot.

Forging

A red hot ‘ingot’ can be shaped by pounding with a metal ‘ram’. Usually the bed of the forge and the ram hold two halves of a mould called a ‘die’.

Casting

Hot liquid metal is poured into a mould where it solidifies. The mould is broken open and the metal ‘casting’ is released.

Rolling

A red hot slab may be passed backwards and forwards between rollers. The slab gradually gets longer and thinner — like dough under a rolling pin.

Extrusion

Soft lead alloys can be made into thin-walled tubes by ‘extrusion’. When the ram hits the metal, the metal is forced up the sides, forming a tube.

Drawing

A tempered metal rod is pulled through a die. This process is repeated through narrower dies until the rod becomes a long thin wire.

Machining

Metal which has been shaped may need to be trimmed in a ‘lathe’. The rotating metal is held firmly while a sharp, hard blade trims it.