How to correctly select and use nozzle nozzles in laser cutting is one of the very important components during laser cutting. It is located at the bottom of the laser head, and the laser beam and auxiliary gas are emitted through the nozzle. Its main function is to gather auxiliary gas and form high pressure, which is released to the surface of the cutting material and the cutting seam, blowing away the melted and vaporized base material generated during the cutting process, leaving a clean cutting seam; At the same time, it prevents pollutants such as slag and smoke from rebounding upwards, thereby protecting the internal lenses.
The concentricity between the center of the nozzle and the laser beam is one of the important factors affecting cutting quality. Therefore, it is necessary to make the nozzle coaxial with the laser beam in order to obtain a better cutting surface.
The effect of different axes between the nozzle center and the laser beam center on cutting quality
(1) The cutting gas is sprayed out from the center of the nozzle and acts on the surface of the sheet metal and the weld seam. If the laser is not in the center of the nozzle, the position of the laser action deviates from the direction of the airflow, which can easily lead to inconsistent cross-sectional effects in different directions.
(2) If the laser is not in the center of the nozzle, it may hit the inner wall of the nozzle, affecting the cutting effect and seriously burning the nozzle directly.
Adjustment method for coaxiality between nozzle and laser beam:
1) Apply transparent tape to the nozzle opening, which will leave circular marks on the nozzle opening.
2) With a power of around 300W, the laser will penetrate the tape and leave a small hole.
3) Remove the transparent tape and observe the relative position of the small hole to the circle.
If the small hole is in the center of the circle, it indicates that the laser is coaxial with the nozzle; If the small hole does not coincide with the center of the circle (different axes), or if the small hole cannot be seen (the laser beam may hit the inner wall of the nozzle), it is necessary to adjust the adjustment screw on the laser cutting head, and then perform spot shooting comparison until the laser output center coincides with the center of the nozzle.
Selection of nozzle type
Generally, laser cutting nozzles are divided into single-layer nozzles and double-layer nozzles. Single layer nozzles are usually used for cutting stainless steel, aluminum alloys, copper alloys, etc., and nitrogen is generally used as an auxiliary gas. Double layer nozzles are generally used for high-speed cutting due to their high gas flow rate, and are usually used for oxygen cutting of carbon steel. However, their cutting surface may turn black due to oxidation.
Selection of nozzle size
The size of the nozzle diameter determines the gas flow rate entering the base material and the cutting seam, thereby affecting the removal of molten material. The higher the gas flow rate and speed entering the incision, the stronger the ability of spraying to remove molten materials.
In theory, the thicker the plate, the larger the nozzle should be used. However, the larger the aperture of the nozzle, the greater the probability of sparks from the molten material splashing upwards during cutting, resulting in a shorter lifespan of the lens.
