How to choose the correct nozzle for laser cutting
Nozzle, also called copper nozzle, is one of the most important parts in laser cutting. The nozzle is located at the lower end of the cutting head. Both the laser beam and the auxiliary gas act on the cutting material 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, and blow it away during the cutting process. The resulting molten and vaporized base metal leaves a clean kerf; at the same time, contaminants such as slag and soot are prevented from rebounding upward, thereby protecting the inner lens.
To get a better cutting section, it is necessary to control the concentricity of the laser beam and the center of the nozzle, the center of the nozzle and the laser beam
The concentricity between the center of the nozzle and the laser beam is one of the important factors affecting the cutting quality. Therefore, the nozzle must be coaxial with the laser beam to obtain a better cutting section.
When the nozzle center is not coaxial with the laser beam center, the effect on the cutting quality:
1. The cutting gas is sprayed from the center of the nozzle, and the center point of the nozzle is the center point of the plate to be cut. If the laser is not in the center of the nozzle, the laser action point will deviate from the actual one, and the actual cutting effect will be obviously inconsistent with the expected effect.
2. If the laser is not in the center of the nozzle, the beam will hit the inner wall of the nozzle during normal operation, which will burn the nozzle seriously and affect the actual cutting effect.
To verify that the laser beam is concentric with the nozzle, the following steps are required for testing:
1. Paste transparent tape on the nozzle mouth, and completely overlap the circular edge with the tape;
2. Adjust the power of the equipment to about 100W, and irradiate the scotch tape with laser in the spot mode;
3. Remove the scotch tape and observe the positional relationship between the circular edge and the laser perforation.
If the perforation is in the center of the circle, it means that the laser beam and the nozzle are concentric and coaxial, and no adjustment is required; if the small hole is not coaxial with the center of the circle, or the small hole cannot be seen (the laser beam hits the inner wall of the nozzle), the laser needs to be adjusted To adjust the screw on the cutting head, repeat steps 1-3 above until the laser perforation point coincides with the center of the nozzle.
Choice of nozzle types:
The nozzles are divided into single-layer and double-layer nozzles. The single-layer nozzle has a slow relative gas flow rate, and is often used for cutting stainless steel, aluminum alloy, copper and other metals, and nitrogen is often used as an auxiliary gas. The double-layer nozzle has a fast gas flow rate and is suitable for high-speed cutting. It is often used for cutting carbon steel. Generally, oxygen is used as an auxiliary gas. The cutting surface is usually blackened due to oxidation.
Choice of nozzle size:
The size of the nozzle size determines the gas flow rate acting on the cut material, which affects the melt removal. The larger the airflow and the faster the speed of the air entering the incision, the stronger the ability of jetting to remove the melt.
In theory, the thicker the sheet, the larger the nozzle should be used. However, the larger the aperture of the nozzle, the greater the chance of the melt sparks flying upwards when cutting, making the life of the lens shorter.
When the nozzle is deformed or there is molten stain on the nozzle, it will affect the cutting effect. Therefore, the nozzle should be placed carefully to avoid bumps or deformation, and the nozzle should be cleaned in time when it is stained with molten stains.
