Laser cutting application
Fast axial flow CO2 lasers are mostly used for laser cutting of metal materials, mainly because of their good beam quality. Although the reflectivity of most metals to CO2 laser beams is quite high, the reflectivity of the metal surface at room temperature increases with the increase of temperature and oxidation degree. Once the metal surface is damaged, the reflectivity of the metal is close to 1. For metal laser cutting, a higher average power is necessary, and only high-power CO2 lasers have this condition.
1. Laser cutting of steel materials
1.1 CO2 continuous laser cutting The main process parameters of CO2 continuous laser cutting include laser power, type and pressure of auxiliary gas, cutting speed, focal position, focal depth and nozzle height.
(1) Laser power Laser power has a great influence on cutting thickness, cutting speed and incision width. When other parameters are constant, the cutting speed decreases with the increase of cutting plate thickness and increases with the increase of laser power. In other words, the greater the laser power, the thicker the plate that can be cut, the faster the cutting speed, and the slightly larger the incision width.
(2) Type and pressure of auxiliary gas When cutting low carbon steel, CO2 is used as auxiliary gas to utilize the heat of iron-oxygen combustion reaction to promote the cutting process. The cutting speed is high and the incision quality is good, especially the incision without sticky slag can be obtained. When cutting stainless steel, CO2 is used. Slag is easy to stick to the lower part of the incision. CO2 + N2 mixed gas or double-layer gas flow is often used. The pressure of the auxiliary gas has a significant effect on the cutting effect. Appropriately increasing the gas pressure can increase the cutting speed without sticky slag due to the increase in gas flow momentum and the improvement of slag removal capacity. However, if the pressure is too high, the cut surface becomes rough. The effect of oxygen pressure on the average roughness of the incision surface is shown in the figure below.