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2021-08-05 15:49:43 Hits（1537）
In the process of laser cutting, it is necessary to use auxiliary gas to blow away the slag in the slit, cool the surface of the processed object to reduce the heated area, and cool and protect the lens of the laser head. Auxiliary gases generally include oxygen, nitrogen, compressed air, etc., which directly affect the cutting performance, cutting speed, and cutting thickness. It is necessary to use different auxiliary gases according to the difference in cutting materials.
Oxygen is often used to cut thick carbon steel materials. Because its chemical reaction heat with an iron will promote the endothermic melting of the metal, the cutting efficiency can be greatly improved. However, oxygen will cause the material to be cut to produce an obvious oxide film on the end face of the cut, and it will have a quenching effect on the material around the cut surface, increase the hardness of this part of the material, and have a certain impact on the subsequent processing. The cut end face of the material cut by oxygen is black or dark yellow. Generally, carbon steel plates are cut by oxygen, low-pressure punching, and low-pressure cutting. Oxygen is generally vaporized from liquid oxygen provided by air separation plants, so the quality of the gas source is clean and no special treatment is required.
When nitrogen is used as an auxiliary gas for cutting, it will form a protective atmosphere around the molten metal to prevent the material from being oxidized, avoid the formation of oxide film, and realize the non-oxidized cutting of the material. But the cutting ability is not as good as oxygen, and the nitrogen consumption of nitrogen cutting is relatively large, and the cutting cost is higher. The non-oxidized cutting surface has the characteristics of direct welding, painting, strong corrosion-resistance, etc., and the cut end surface is white. Generally use nitrogen to cut stainless steel, galvanized sheet, aluminum and aluminum alloy, brass and other materials, use low-pressure perforation, and use high-pressure cutting. During nitrogen cutting, the change of gas flow has a great impact on cutting. When cutting gas pressure is ensured, sufficient gas flow must be ensured. Nitrogen is generally vaporized from liquid nitrogen provided by air separation plants, so the quality of the gas source is clean and no special treatment is required.
Compressed air is easier to obtain than oxygen and nitrogen, and the price is very cheap. The air contains about 20% oxygen and 78% nitrogen. The cutting efficiency is far less than that of oxygen cutting, but the cutting ability is close to that of nitrogen, and the air cutting efficiency is slightly higher than that of nitrogen cutting. Due to the presence of oxygen, the end face of the incision turns yellow. When there is no strict requirement on the color of the cut surface of the material, using compressed air instead of nitrogen cutting is the most economical and practical choice. Generally used to cut sheet metal, aluminum, non-metal, and galvanized sheet materials, it can reduce oxidation to a certain extent. Membrane and save the cost of use, is currently one of the more and more cutting gas sources.
Compressed air can be obtained directly with an air compressor, but the air itself is not clean. Compressed air contains a large amount of water, oil, particles, and other pollutants. If the compressed air is not pure, it will cause high-pressure jets to the protective mirror of the laser cutting head. , Will contaminate the protective lens (as shown in the picture above), seriously affect the transmission of the laser beam, disperse the focus, cause the product to be impenetrable, prone to burrs (as shown in the picture below), and the cutting surface is rough (as shown in the picture below), etc., and even produce waste products. If it is a high-power laser cutting machine, as long as the protective mirror or nozzle surface sticks a little very fine oil film or water mist, it may also cause the high-energy laser to burn out the laser head.
