Originally, plasma cutting was developed for the purpose of cutting all those materials which could not be cut with oxy-fuel due to their chemical structures. This concerns primarily high-alloyed steels, aluminium and copper. Particularly due the small heat-affected zone and high cutting speeds, this process soon became accepted within the industry also for mild steel. Generally, plasma cutting technique can be used to cut all electrically conductive materials. Depending on the material, certain consumables and plasma gases are selected in order to always achieve the optimum cut results. The further development of one process variant even showed the possibility to cut insulating materials like glass, concrete or interrupted structures with plasma (see Hot-Wire).