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  • The role of

  • fiber laser cutting nozzle

  • Nozzle
    For fiber laser cutting
    The fiber laser cutting nozzle is located at the bottom of the laser head, which is the closest parts to the workpiece. The focused laser and high-pressure air flow are emitted through the nozzle, so it plays a very critical role in the cutting process. It is also one of the most common consumables and most important parts on the laser head.
  • Functions
    of fiber laser nozzle

    1. Through the internal shape of the laser head nozzle, adjust the air flow          direction and air pressure of the high-pressure air flow to maintain the pressure between the workpiece and the nozzle.

    2. Prevent the molten material of the workpiece from splashing back into the laser head, thereby protecting the lens inside the laser head.

    3. Provide the capacitance signal to the height adjustment system to ensure the stable operation of the height adjustment system.

  • How to choose the nozzle correctly and reasonably in cutting
    1. ypes and characteristics of nozzles. The most widely used conical nozzles are divided into single-layer nozzles and double-layer nozzles. After the double-layer nozzle gas passes through the inner core, it will undergo secondary expansion to increase the gas velocity, and then reach the working surface through the end hole. The advantage of this is that it can reduce the generation of shock waves and increase the gas velocity, thereby improving the efficiency of the gas participating in the cutting, taking away the slag and heat.


    2, the nozzle aperture and plate thickness match

    Due to the type of plate, power section and auxiliary gas, the choice of nozzle aperture will also change accordingly. The following is an example of carbon steel for comparison. However, the larger the aperture of the nozzle, the smaller the protective effect on the focusing lens. Therefore, a reasonable choice of the size of the nozzle aperture of the laser cutting machine can produce more efficiently.


    3. Common operations for nozzle damage

    The nozzle is one of the most common lossy products of the laser head. In order to avoid unnecessary loss as much as possible, the following is a list of common operations where two nozzles are damaged.




    The nozzle should pay special attention to two issues


    1. Influence of nozzle diameter:

    The size of the nozzle opening has a certain influence on the cutting speed, and the size of the nozzle opening also affects the pressure distribution at the outlet. The diameter of the nozzle is increased. Due to the strong cooling effect of the jet flow on the base material in the cutting zone, the heat affected zone is narrowed, but it also causes the slit to be too wide, and the nozzle size will cause collimation difficulties, and the nozzle mouth may be cut by the beam. And, the slit is too narrow, which will hinder the smooth discharge of slag at high cutting speed.


    2. The effect of the distance between the nozzle and the surface of the workpiece:

    The distance between the nozzle and the workpiece directly affects the coupling between the nozzle airflow and the workpiece slit. The nozzle opening is too close to the surface of the workpiece, which will produce a strong return pressure to the lens, weakening the ability to disperse the material point of the splatter cutting, and adversely affect the cutting quality, but too far away will cause unnecessary loss of kinetic energy. Effective cutting is also disadvantageous. Generally, the distance between the nozzle and the workpiece should be controlled within 1~2mm. The torch of modern laser cutting system is equipped with inductive or capacitive sensor feedback device to automatically adjust the distance between the two within the preset height range.







    Basic requirements for choosing laser nozzles

    1. Good material

    A good nozzle must use TU2 copper, because of its high conductivity and good thermal conductivity, so as to ensure a good capacitance signal.


    2. High processing accuracy

    A good laser head nozzle should have a concentricity of 0.03mm, and a nozzle with a size of less than 1.0mm should have a concentricity of 0.02mm. The high-precision concentricity nozzle can not only reduce the early debugging 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.


    3. There must be a highly polished laser head surface

    Laser head nozzles have a roughness requirement of up to 0.8 on both internal and external surfaces. The high-gloss outer surface can effectively reduce the adhesion of the melt during the cutting process, thereby extending the life of the nozzle; and the high-gloss inner surface can effectively avoid the vortex generated when the high-pressure gas flows out. Improve cutting quality and efficiency.