The laser cutting market is booming, how to choose the nozzle?

In the laser cutting process, the quality of the laser beam, the material, the laser power, and the thickness of the workpiece all profoundly affect the quality and performance of laser cutting. In addition, the nozzle design of the laser cutting head is also one of the important factors affecting the cutting quality.

1. The influence of the nozzle on the cutting quality
   The nozzle plays a very important role in laser cutting. Its main purpose is to release the auxiliary gas to the surface of the cutting material and the kerf, so that the molten and gasified base material generated during the cutting process is discharged, leaving A clean cut. If the nozzle is not designed and maintained properly, and the machining accuracy is not enough, the flow velocity of the gas will be weakened, and the direction of the airflow will become unstable, which will affect the removal of materials during the cutting process and eventually lead to unsatisfactory cutting results. The concentricity between the center of the nozzle and the laser is one of the important factors that cause cutting quality, especially when the workpiece to be cut is thicker, its influence will be greater. Therefore, the concentricity between the center of the nozzle and the laser must be adjusted to obtain a better cutting section.
   When the center of the nozzle is not in the same axis as the center of the laser, the impact on the cutting quality:
   1) It affects the cutting section. When the cutting gas is sprayed out, the gas volume is uneven, so that the cutting section is more likely to have melted stains on one side, but not on the other side. It has little influence on cutting thin plates below 3mm. When cutting a plate above 3mm, its impact is more serious, and sometimes it cannot be cut.
   2) It affects the quality of sharp corners. When cutting workpieces with sharp corners or small angles, local over-melting is prone to occur. When cutting thick plates, it may not be able to cut.
   3) Affect the 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, and have little effect on the perforation of thin plates.
   Coaxial adjustment method:
   1) Put scotch tape on the nozzle opening.
   2) Use 10%-20% power hand laser to shoot.
   3) Remove scotch tape, being careful to keep it oriented so it compares to the nozzle. Under normal circumstances, there will be a small spot left on the scotch tape, which is burned by the laser, but if the center of the nozzle deviates too much from the center of the laser, this point will not be visible (the laser beam hits the nozzle wall). Synchronously adjust the adjustment screw on the handle of the mirror cavity until the hole punched by the laser on the white sticker coincides with the center of the nozzle, so as to confirm that the center of the laser output is consistent with the center of the nozzle.
2. How to choose the nozzle
   Nozzle size: Select the nozzle size according to the thickness of the metal sheet cut by the user. The aperture of the nozzle controls the flow rate of the gas and the shape of the gas field, which is very important to the cutting quality. Generally, when using a laser cutting machine to cut a thin plate below 3mm, it is recommended to use a nozzle with a diameter of 1mm, and a nozzle with a diameter of 1.5mm is recommended for a thickness above 3mm. When cutting metal sheets over 10mm, nozzles with a diameter of 2mm or more are generally selected.
   Nozzle material: For a good nozzle, the material must have high electrical conductivity and good thermal conductivity. Generally, the nozzle made of copper is better than that made of brass, which can ensure a good capacitive signal.
   Nozzle processing accuracy: A good laser head nozzle should have a concentricity of 0.03mm, and a nozzle with a size below 1.0mm should have a concentricity of 0.02mm. The high-precision concentricity nozzle can not only reduce the pre-adjustment in the processing process, but also effectively prevent the high-energy laser from hitting the inner wall of the laser head, thereby avoiding damage to the laser head.
   Nozzle surface smoothness and anti-oxidation treatment: smooth surface and good anti-oxidation treatment can effectively reduce the adhesion of molten material during cutting and prolong the service life of the nozzle.

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