Laser cutting is the use of high-power density laser beam to irradiate the material to be cut, so that the material is quickly heated to the melting point, forming holes. With the movement of the beam, the holes continuously form slits with a narrow width (about 0.1mm). The high-speed airflow with the coaxial beam blows away the molten material to complete the cutting of the material.
It is necessary to add auxiliary gas suitable for the material being cut during the cutting process. The auxiliary gas mainly includes oxygen, nitrogen, air and argon. When cutting steel, oxygen is used as an auxiliary gas to produce an exothermic chemical reaction with molten metal to accelerate cutting. Nitrogen is the better choice when processing stainless steel. Stainless steel will turn black when oxidized. Nitrogen can prevent the incision from turning black. Try to choose high-purity nitrogen. When cutting plastics such as polypropylene, compressed air is used. Inert gas is used for cutting combustible materials such as cotton and paper. The auxiliary gas entering the nozzle can also cool the focusing lens and prevent smoke and dust from entering the lens holder.
When the laser cutting machine cuts the steel plate, as the thickness of the plate increases, the oxygen purity of the incision is likely to decrease, thereby affecting the temperature of the incision. The purity of the oxygen flow has a strong influence on the cutting process. After testing, when the purity of the oxygen stream drops by 0.9%, the iron-oxygen combustion rate will drop by 10%; when the purity drops by 5%, the combustion rate will drop by 37%. The reduction in burning rate will greatly reduce the energy input into the slit, thereby reducing the cutting speed. At the same time, the increase of iron content in the liquid layer of the cut surface also increases the viscosity of the slag, making it difficult to be discharged. In this way, serious dross will appear in the lower part of the incision, and the quality of the incision will decrease.