Effects of high-pressure assistant-gas flow on high-power CO₂ laser cutting

The main objective of this research is to investigate CO₂ laser cutting performance on 3 mm thick mild steel plate with assistant-gas pressures of up to 10 bar. A co-axial cutting nozzle able to withstand pressures of up to 12 bar was designed and set up. Experiments were performed with this high-pressure coaxial nozzle. The cutting edges were examined to provide information on cutting quality. The results show that an acceptable-quality cutting region does not exist for pure oxygen cutting, but that good cutting can not be obtained at an assistant-gas pressure of over 4 bar with 3 mm thick mild-steel plate. For inert-gas cutting, dross under the cut kerf was formed with most of the cutting parameters. An almost clean cut was found with an argon gas pressure of 10 bar at a cutting speed of 25 mm s^-1. For the laser cutting of 3 mm thick mild steel plate it is advised that oxygen cutting is still the best, although argon and nitrogen may be used instead. Air is inferior to these gases as an assistant gas.