How to choose and use the correct nozzle for laser cutting

Nozzle, is one of the very important parts when laser cutting. It is located at the very bottom of the laser head, the laser beam and the auxiliary gas are shot through the nozzle, its main function is to: gather the auxiliary gas and form a high pressure, release it into the surface of the cutting material and the slit, blow away the molten and vaporized base material produced during the cutting process, leaving a clean slit; at the same time, stop the slag, soot and other pollutants from bouncing upwards, thus protecting the internal lens.

The concentricity of the center of the nozzle and the laser beam is one of the most important factors affecting the quality of the cut. Therefore, the nozzle must be made coaxial with the laser beam to obtain a better cutting surface.

Nozzle center and the laser beam center is not the same axis, the impact on the cutting quality

(1) cutting gas from the center of the nozzle, the action on the surface of the plate and weld, if the laser is not in the center of the nozzle, the laser action position and airflow blowing to produce deviations, prone to inconsistent results in different directions section.

(2) the laser is not in the center of the nozzle, may hit the inner wall of the nozzle, affecting the cutting effect, serious direct burn nozzle.

Nozzle and laser beam coaxiality adjustment method.

1) Put a transparent tape on the nozzle mouth, the tape will leave a circular trace of the nozzle mouth.

(2) with a power of about 300W point shooting, the laser will shoot through the tape and leave a small hole.

(3) Remove the transparent tape and observe the relative position of the small hole and the circle.

If the small hole in the center of the circle, indicating that the laser and nozzle coaxial; if the small hole and the center of the circle do not coincide (different axis), or can not see the small hole (the laser beam may hit the inner wall of the nozzle), you need to adjust the adjustment screw on the laser cutting head, and then point shooting comparison, until the laser out of the center and the center of the nozzle coincide.

Nozzle type selection

General laser cutting nozzle is divided into single-layer nozzle and double-layer nozzle. Single-layer nozzle is usually used for cutting stainless steel, aluminum alloy, copper alloy, etc., and generally uses nitrogen as the auxiliary gas. Double-layer nozzle is generally used for high-speed cutting because of its high gas flow rate, and is usually used for cutting carbon steel with oxygen, but its cutting surface will be blackened by oxidation.

Nozzle Size Selection

The size of the nozzle diameter determines the gas flow rate into the base material and the cut, which affects the melt removal. The higher and faster the gas flow rate into the cut, the better the ability of the jet to remove the melt.

Theoretically, the thicker the sheet, the larger the nozzle should be used. However, the larger the aperture of the nozzle, the greater the chance of sparks from the melt splashing and bouncing upward during cutting, making the life of the lens shorter.