Plasma cutting comes from the pre-existing technology of plasma welding, used both to treat surfaces and to weld parts. The inventive step which leads to plasma cutting arrives with the patent of Robert Cage in 1955, which adds a nozzle. The result of the presence of this element is a thin jet so powerful to separate materials. The gas the nozzle blows, generating an electric arc, is transformed in plasma, which, thanks to its heat, melts and cuts metals such as steel, aluminum, copper and other metal materials. Usually the employed gases are compressed air, nitrogen, oxygen or argon-hydrogen. Plasma cutting system is used both for small and thick metal sheets. In the past this technology was used only for conductor materials, while nowadays its use is wider, thanks to an ignition arc contained inside the nozzle. Over time also the cutting quality has been improved; this is the case of Hypertherm, leading company in the production of plasta cutters, which, improving the cutting quality has been able to obtain great finish processing.