Oxy-fuel cutting is most accurately described as rapid controlled rusting. It is used to cut metal using a process that breaks down the composition of the metal, rather than more conventional cutting techniques which cut with a direct, physical action.

Oxy-fuel cutting works by using preheat flames to raise the surface or edge of a metal, for example steel, to approximately 1800°F . Pure oxygen is then directed toward the heated area in a fine, high pressure stream. The steel is rapidly oxidised and is blown away from the cutting area, which leaves a cavity. The preheat and oxygen stream are moved at consistent pace to form a continuous cut.

For a metal to be cut with this process it must have oxides with a lower melting point than the base metal itself. If it doesn’t the metal will oxidise too quickly, preventing complete oxidation by forming a protective crust.

Low carbon steel and some low alloys are the only metals that can be cut effectively with the oxy-fuel process.