In the process of using the laser cutting machine, many customers will have unstable cutting quality. When checking the problem, they will find a layer of water mist on the surface of the protective lens. When it is wiped dry, the cutting quality will be unstable again after a short time of use, and it is repeated. What is the reason for this?
As we all know, the laser cutting machine needs to use auxiliary gas when cutting. The common auxiliary gas is divided into three types: nitrogen, oxygen and air. Let's first understand the performance of different gases in laser cutting and the materials suitable for cutting.
1. Oxygen
It is mainly used for cutting carbon steel with laser cutting machine. When the oxygen reaction heat is used to improve the cutting efficiency in large format, the oxide film produced will improve the beam spectral absorption factor of the reflective material. The end face of the incision is black or dark yellow. It is mainly applicable to rolled steel, rolled steel for welding structure, carbon steel for mechanical structure, high tension plate, tool plate, stainless steel, electroplated steel plate, copper, copper alloy, etc.
2. Nitrogen
When some metals are cut, oxygen will form an oxide film on the cutting surface, and nitrogen can be used for non oxidizing cutting to prevent the appearance of oxide film. The oxidation free cutting mask can be directly welded and coated, and has strong corrosion resistance. The end face of the incision is white. The main applicable plates are stainless steel, galvanized steel plate, brass, aluminum, aluminum alloy, etc.
3. Air
Air can be directly supplied by air compressor, so it is very cheap compared with other gases. Although the air contains about 20% oxygen, the cutting efficiency is far less than oxygen, and the cutting capacity is similar to nitrogen. A small amount of oxide film will appear on the cutting surface, but it can be used as a measure to prevent the coating layer from falling off. The end face of the incision is yellow. The main applicable materials are aluminum, aluminum alloy, stainless copper, brass, galvanized steel plate, non-metal, etc.
When many customers use air cutting, water mist for lens protection is concentrated, and the air source is mainly air compressor. Air provides cooling and cleaning effect for laser lens and cutting lens to prevent pollutants from reflecting in from air nozzle. However, the air contains a lot of moisture and impurities. If no purification treatment is carried out, it will cause great harm to optical elements, especially the harm of moisture. The air pipe used for blowing is close to the focusing lens. If there is water, it will be easily splashed on the focusing lens when blowing air through the air outlet. The focusing lens has temperature during operation, which will condense when meeting water and cause astigmatism, leading to insufficient laser focusing intensity and accuracy, seriously affecting the cutting quality. The focusing lens is easy to break down after a long time. Therefore, it is necessary to configure desiccant to cooperate with the air compressor for filtering and drainage, but not all dryers can meet the requirements of laser gas.
Therefore, the dryer is the culprit of water mist in the laser cutting process. So how do we choose the dryer matched with the laser cutting machine?
Common dryers on the market are mainly of freezing type and adsorption type:
1. Refrigerated dryer: Due to technical limitations, the refrigerated dryer is generally used for compressed air with low requirements. Because the minimum pressure dew point of the cold dryer can only reach 3 ℃, it can not meet the requirements for the dryness of the air used by the laser cutting machine.
2. Adsorption dryer: If there is no liquid water at the air outlet, only adsorption dryer can be selected. The pressure dew point of the die core adsorption dryer can continuously and stably reach - 40 ℃, and the maximum can reach - 80 ℃, which can fully meet the requirements of laser cutting processing.
The purpose of using air is to save costs, but at the same time of saving costs, you must not choose poor air compressors and dryers, otherwise unstable cutting will lead to material waste, which will cause greater losses.