Machine tools are power-driven devices used to cut, shape or form metal in the production of durable goods. The tools also are employed in non-metalworking industries, such as fast foods, where small steel presses stamp out meat patties.
Every plane, bus, train--or for that matter, bicycle or tricycle--was in some way produced by a machine tool. The same holds true for every gun, tank or nuclear missile, which gives the machine tool industry strategic importance.
There are six basic types of metal-cutting machine tools, including drilling machines, milling machines, boring, turning machines (lathes, for example); and grinding and polishing, and sawing machines.
Turning machines, which operate by applying a stationary cutting edge to a rotating workpiece, are used to manufacture round products, such as cylinders. Milling machines use rotating cutters to cut the surface of a rotating workpiece. Drilling and boring machines are used to cut holes in metal. Grinding and polishing machines use grinding wheels to remove metal from workpieces of various shapes.
There are also six basic kinds of metal-forming machine tools, including punching machines, shearing machines, bending and forging machines, die-casting machines and presses.
Metal forming machines shape metal through pressure. Sheet metal is shaped into car bodies and other durable goods shells by punching machines. Shearing machines cut sheet metal with a blade that is forcefully applied to the metal. Arcs, angles, and hollow cylinders are bent into shape by bending machines. Presses apply tremendous force to bend, cut or punch metal. Forges, often found in the steel industry, compress pre-heated metal--such as billets and blooms--into structural shapes, such as I-beams.
Die-casting machines inject molten metal into die sets, or molds, to produce more complicated shapes.