1.The relationship between nozzle and cutting quality:
When the nozzle center and the laser center are not on the same axis, the effect on cutting quality:
1) Affect the cutting section. When the cutting gas is sprayed out, it will cause uneven air volume, which makes it easier for the cutting section to have melting stains on one side and not on the other side. It has little effect on cutting thin plates below 3mm. When cutting a sheet of more than 3mm, its impact is more serious, and sometimes it will not be able to cut.
2) It affects the quality of sharp corners. When cutting workpieces with sharp corners or small angles, local overmelting is likely to occur. When cutting thick plates, it may not be possible to cut.
3) Affect the perforation, the instability during perforation, the time is not easy to control, the penetration of thick plates will cause overmelting, and the penetration conditions are not easy to grasp, and the perforation of thin plates is less affected.
2.Selection of nozzle aperture:
There are several types of nozzle apertures, such as φ1.0mm, φ1.5mm, φ2.0mm, φ2.5mm, φ3.0mm, etc. At present, two kinds of nozzle apertures are usually φ1.5mm and φ2mm.
1）Thin plates below 3mm: Use φ5mm, the cutting surface will be thin; use φ2mm, the cutting surface will be thicker, and the corners will be easily melted.
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. Use a φ1.5mm nozzle, the gas diffusion area is small, so it is not stable when used, but it is basically usable. use a φ2mm nozzle, the gas diffusion area is large and the gas flow rate is slow, so the cutting is more stable.
3) The hole diameter of 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 cutting quality and perforation quality. At present, laser cutting mostly uses nozzles with φ1.5mm and φ2mm apertures.
Therefore, when the nozzle aperture is larger, the relative protection of the focusing lens is worse, because the sparks of the melt splash during cutting and the probability of bouncing upward is great, making the life of the lens shorter.
The concentricity between the center of the nozzle and the laser is one of the important factors that cause the cutting quality, especially when the workpiece is cut thicker, its influence is greater. Therefore, the concentricity between the nozzle center and the laser must be adjusted to obtain a better cutting section.
Note: When the nozzle is deformed or there are melting stains on the nozzle, its impact on the cutting quality is the same as described above. Therefore, the nozzle should be placed carefully and not bumped to avoid deformation; the melting stains on the nozzle should be cleaned up in time . The quality of the nozzle has high precision requirements during manufacturing, and the correct method is required during installation. If various conditions need to be changed during cutting due to the poor quality of the nozzle, the nozzle should be replaced in time.