01 The relationship between nozzle and cutting quality
When the center of the nozzle is not coaxial with the center of the laser, the influence on the cutting quality:
1) Affect the cutting section. When the cutting gas is ejected, the gas volume is uneven, which makes it easier for the cutting section to have melting stains on one side and no phenomenon on the other side. When cutting a sheet of more than 3mm, its impact is more serious, and sometimes it can’t be cut.
2) It affects the quality of sharp corners. When cutting workpieces with sharp corners or small angles, local over-melting is easy to occur. When cutting thick plates, it may not be possible to cut.
3) Affects perforation. It is unstable during perforation, and the time is not easy to control. The penetration of thick plates will cause over-melting, and the penetration conditions are not easy to grasp, so the impact on the perforation of thin plates is small.
02 How to choose the aperture of the nozzle
The diameter of the nozzle varies from φ1.0mm to φ5.0mm. At present, two kinds of nozzle apertures, φ1.5mm and φ2mm, are often used. The difference between the two is:
1) Thin plate below 3mm: When φ1.5mm is used, the cutting surface will be thinner; when φ2mm is used, the cutting surface will be thicker, and the corners are prone to melting.
2) Thick plates above 3mm: due to the high 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 in use, but it is basically still usable. With φ2mm, 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. To sum up, the size of the nozzle aperture has a serious impact on the cutting quality and perforation quality. At present, the nozzles with φ1.5mm and φ2mm apertures are mostly used in laser cutting.
Therefore, when the nozzle aperture is larger, the relative protection of the focusing lens will be worse, because the spark of the melt splashes during cutting, and the probability of bouncing up is high, making the life of the lens shorter.
The concentricity between the center of the nozzle and the laser is one of the important factors for the quality of cutting, especially when the workpiece to be cut is 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 molten stains on the nozzle, its impact on the cutting quality is the same as the above-mentioned. Therefore, the nozzle should be placed carefully and not bumped to avoid deformation; the molten stain on the nozzle should be cleaned in time. . The quality of the nozzle has high precision requirements during manufacture, and the installation method also requires the correct method. If the cutting conditions need to be changed due to the poor quality of the nozzle, the nozzle should be replaced in time.
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