In the working process of laser cutting machine, the pressure of auxiliary gas has a great influence on the cutting result. The auxiliary gas must have enough pressure to completely remove the waste slag generated by laser cutting. Generally, when cutting a thicker workpiece, the air pressure should be reduced a little. The residue stuck to the workpiece will damage the cutting edge.

Increasing the gas pressure can advance the laser cutting speed, but after reaching a certain value, continuing to increase the gas pressure will cause a decrease in the cutting speed. Under high auxiliary gas pressure, the reason for the reduction of cutting speed can be attributed not only to the enhancement of cooling effect of high air velocity on the laser action zone, but also to the interference of intermittent shock wave in the air flow on the cooling of the laser action zone. The uneven pressure and temperature in the air flow will cause the change of air flow field density. Such a density gradient results in the change of the refractive index in the field, which results in the focusing of the beam energy and the refocusing or beam divergence. This interference will affect the melting efficiency, and sometimes it may change the mode structure, resulting in the reduction of cutting quality, if the beam divergence is too large. If the light spot is too large, it may even cause serious consequences that the cutting cannot be carried out effectively.

In order to avoid the adverse effect of high-speed air flow on laser cutting performance, it can be envisaged to change the total pressure distribution in the air flow. Because of this change in the air flow pressure distribution, the melting process occurs in the central low-pressure region; The high pressure zone around it can be increased to enough momentum (momentum) to ensure more effective slag removal. Because the intermittence of the high pressure zone will not interfere with the speed of light, the melting efficiency is also improved.