Influence of laser cutting nozzle on cutting quality and choice of nozzle aperture

1. The relationship between nozzle and cutting quality:

When the center of the nozzle is different from the center of the laser, the effect on the cutting quality:

1) The cutting section is affected. When the cutting gas is sprayed out, the gas volume is not uniform, which makes the cutting section more prone to the phenomenon of melting stains on one side but not on the other side. When cutting a plate of more than 3mm, its impact is more serious, and sometimes it can not be cut.

2) Affect the quality of sharp corners. When cutting workpieces with sharp corners or small angles, it is easy to produce local over-melting phenomenon. When cutting thick plates, it may not be able to cut.

3)Affect the perforation. The instability during the perforation, the time is not easy to control, the penetration of the thick plate will cause over-melting, and the penetration conditions are not easy to grasp, and the impact on the thin plate is small.

2.The choice of nozzle aperture:

The diameter of the nozzle is φ1.0mm, φ1.5mm, φ2.0mm, φ2.5mm, φ3.0mm, etc. At present, the nozzle diameter usually uses φ1.5mm and φ2mm. The difference between the two is:

1) Thin plates below 3mm: using φ1.5mm, the cutting surface will be thinner; using φ2mm, the cutting surface will be thicker, and the corners are prone to melt stains.

2) Thick plates above 3mm: due to the higher cutting power, the relative heat dissipation time is longer, and the relative cutting time also increases. With φ1.5mm, the gas diffusion area is small, so it is not stable when used, but it is basically usable. With φ2mm, the gas diffusion area is large and the gas flow rate is slow, so it is more stable when cutting.

3) Aperture with diameter φ2.5mm can only be used for cutting thick plates over 10mm. In summary, the size of the nozzle aperture has a serious impact on the cutting quality and the quality of the perforation. At present, laser cutting mostly uses nozzles with φ1.5mm and φ2mm apertures.

Therefore, when the nozzle aperture is selected to be larger, the relative protection of the focusing lens is worse, because the spark of the molten material splashes during cutting, and the chance of bouncing upward is large, making the life of the lens shorter.

The concentricity of the center of the nozzle and the laser is one of the important factors that cause the quality of the cutting, especially the thicker the workpiece to be cut, the greater its influence. Therefore, the concentricity of the nozzle center and the laser must be adjusted to obtain a better cutting section.

Note: When the nozzle is deformed or there is molten stain on the nozzle, the impact on the cutting quality is as described above. Therefore, the nozzle should be placed carefully, and no damage can be caused to avoid deformation; . The quality of the nozzle has high accuracy requirements during manufacturing, and it also requires correct methods during installation. If the conditions need to be changed during cutting due to the poor quality of the nozzle, the nozzle should be replaced in time.