The oldest thermal cutting process is oxy/fuel. While most mild steel under 32mm (1¼â€) is cut by other processes, mild steel from 1mm to 1m (12g to 44â€) is cut buy this technically simple process.

The oxy/fuel process uses the chemical properties of steel to burn the mild steel, the torch design directs the oxygen to give a good straight out.

While the oxy/fuel cutting process is cheap and is the only economic method of cutting in the thick plate market, there are problems when cutting thin steel. The heat effected zone of the process is large in comparison to laser and plasma and causes thermal shrinkage. For effective accurate cutting the operator must be highly skilled to compensate for plate movement while cutting.