The importance of air pressure to the operation of laser cutting machines

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

Increasing the gas pressure can advance the laser cutting speed, but after reaching a maximum value, continuing to increase the gas pressure will cause the cutting speed to drop. Under high auxiliary gas pressure, the reason for the decrease in cutting speed can not only be attributed to the enhancement of the cooling effect of the high air velocity and the effect area, but also the interference of the intermittent shock wave existing in the airflow on the cooling of the laser effect area. The uneven pressure and temperature in the airflow will cause changes in the density of the airflow field. Such a density gradient results in a change in the refractive index in the field, thereby constricting the focus of the beam energy, causing refocusing or beam divergence. This interference will affect the melting efficiency, and sometimes it may change the mode structure, resulting in a decrease in cutting quality, if the beam diverges too much. To make the light spot too large may even cause serious consequences that cannot be effectively cut.

In order to avoid the adverse effects of high-speed airflow on laser cutting performance, it is conceivable to change the total pressure distribution in the airflow. Change so that the melting process occurs in the central low-pressure zone; and the adjacent high-pressure zone around it can be increased to sufficient momentum (impulse) to ensure more effective removal of slag. Since the intermittency of the high-pressure zone will not interfere with the speed of light, the melting efficiency is also improved.