How does the laser cutting machine nozzle affect the cutting quality and the choice of nozzle aperture?
The design of the nozzle and the jet flow situation directly affect the quality of laser cutting; the manufacturing accuracy of the nozzle is closely related to the cutting quality. The main functions of the nozzle are:
1). Prevent debris such as cutting melting stains from rebounding upward into the cutting head and damaging the focusing lens.
2) The nozzle can change the condition of cutting gas spraying, and can control the area and size of gas diffusion, thereby affecting the cutting quality.
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 the cutting section more likely 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 plate of more than 3mm, its impact is more serious, and sometimes it can not be cut.
2). Affecting 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). It affects perforation, it is unstable during perforation, and 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 impact on thin plates is small.
To sum up, 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 thicker, its influence is greater. 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 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 higher precision requirements during manufacturing, and the correct method is required during installation. If various conditions need to be changed during cutting due to poor nozzle quality, the nozzle should be replaced in time.
Second, the choice of nozzle aperture
The difference of nozzle aperture is shown in the table below
Nozzle aperture difference
There are several types of nozzle apertures, such as φ1.0mm, φ1.5mm, φ2.0mm, φ2.5mm, φ3.0mm, etc. At present, nozzle diameters are often used in two types: φ1.5mm and φ2mm. The difference between the two is:
1) Thin plates below 3mm: use φ1.5mm, the cutting surface will be thin; use φ2mm, the cutting surface will be thicker, and the corners are prone to melting 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 the cutting is more stable.
3) The hole diameter of φ2.5mm can only be used for cutting thick plates above 10mm.
In summary, the size of the nozzle aperture has a serious impact on the cutting quality and perforation quality. At present, laser cutting mostly uses nozzles with φ1.5mm and φ2mm apertures.
The larger the nozzle aperture, the poorer the protection of the focusing lens. Because the sparks of the melt splash during cutting, the chance of bouncing upward is great, making the life of the lens shorter.