The principle is to focus a lot of energy on a very small area. This is done by a lens. Simply propel an assistance gas to chase away the material, cutting gas. The latter can be of three different types. Oxygen is used to cut steel, there for property to enable combustion. We are talking about black Cup. Nitrogen gives best results in stainless steel and aluminium. It is white cut, i.e. without carbon cutting. The steel can also be machined white Cup for parts to be painted and cannot be sanded.