Laser cutting is a thermal cutting method that uses a focused high power density laser beam to irradiate the workpiece to rapidly melt, vaporize, ablate or reach the burning point of the material at the burning point, and simultaneously blow off the molten material with the auxiliary gas of the high speed airflow coaxial with the beam, so as to realize the cutting of the workpiece.
The air pressure and nozzle determine the surface roughness and burr of the cut section. Proper increase of air pressure in laser cutting is beneficial to slag removal, but excessive pressure will increase the surface roughness value. Nitrogen cutting has the following requirements for gas parameters:
(1) Barometric pressure
Nitrogen does not participate in combustion and is used to blow off liquid materials with relatively low temperature, requiring a high air pressure of (10~14) * 105Pa. The pressure of oxygen cutting is generally not more than 4 * 105Pa.
(2) Nozzle
High pressure is used for nitrogen, and larger nozzle diameter is required to ensure gas output. For example, cutting 2mm thick stainless steel, using nozzle HK10 (ø 10mm) for oxygen, and HK15 (ø 15mm) for nitrogen.
(3) Purity
The purity of nitrogen has a great impact on the cutting quality, and the oxygen content affects the cutting quality. Water will harm the laser, so the gas level should be at least 4.5.