How to choose special screw air compressor for laser cutting machine

How to choose special screw air compressor for laser cutting machine

Laser cutting is the use of laser beam high power density properties, laser convergence to a small spot of light, the material quickly heated, so that it reaches the boiling point after vaporization to form a hole, and then by moving the laser beam on the surface of the material to create a slit, complete the cutting of the processing object.

Laser cutting is one of the thermal cutting methods, which can be divided into laser gasification cutting, laser melting cutting, laser oxygen assisted melting cutting and controlled fracture cutting.

Working principle of laser cutting

Compared with other cutting methods, laser cutting is characterized by fast cutting speed and high quality. Specifically summarized as the following aspects:

(1) The laser gas cutting incision is narrow, the two sides of the slit are parallel and good perpendicularity with the surface.

(2) Good cutting quality. Because the laser spot is small, the energy density is high, the cutting speed is fast, so the laser cutting can get better cutting quality.

(3) Cutting surface smooth and beautiful, even as the last processing process, without mechanical processing, parts can be directly used.

(4) cutting speed, such as: 2500W laser cutting 1mm thick cold rolled carbon steel plate, cutting speed up to 16-19m/min.

(5) non-contact cutting, laser cutting nozzle and workpiece no contact, there is no tool wear.

(6) after laser cutting, the width of the heat affected zone is very small, the performance of the material near the slit is almost unaffected, and the workpiece deformation is small, and the cutting accuracy is high. Laser cutting and other cutting methods of cutting speed comparison see the table below, cutting material for low carbon steel plate.

Comparison of cutting speed of several cutting methods:

First, to advance in the direction of high power, high precision and large area

In recent years, domestic laser cutting machine technology has a breakthrough development, and toward the direction of high power, high precision, large area. In the context of Intelligent manufacturing in China, the industrial field has shown a trend of transformation from traditional processing to high-end manufacturing, and the market size of Laser cutting in China will always maintain a trend of rapid development.

Two, laser cutting laser equipment market accounted for 39%

In 2019, although the laser market grew, the growth rate began to slow down compared with the previous two years. The sales revenue of laser equipment in all fields (including imports) was 65.8 billion yuan, up 8.8% year on year. Affected by the uncertainty of the global economic trend, it is expected that the overall sales revenue of China's laser equipment market in 2020 will be 64.5 billion yuan, and there will be the first negative growth in nearly a decade, but its prospects are still broad and the absolute amount is not small.

In the industrial laser equipment market, laser cutting is the most widely used, accounting for 39%, marking and welding are the second and third, accounting for 19% and 12% respectively.

Three, compressed air in the field of laser cutting application

Laser cutting machine can cope with the cutting requirements of various materials and complex shapes, in addition to the need to provide high energy lasers, auxiliary gas is an indispensable material to complete the cutting process. The auxiliary gas for laser cutting is mainly oxygen (O2), nitrogen (N2) and Compressed Air (Compressed Air) three. Compressed air is more readily available than oxygen and nitrogen, is very cheap compared to oxygen and nitrogen, and the use of compressed air as an auxiliary gas for cutting is very common.

Compressed air quality has a very direct effect on the quality of metal laser cutting, the size and stability of gas pressure will affect the effect of cutting. Supporting the laser cutting machine as an auxiliary gas air compressor specifications size of the choice, mainly should be based on the laser cutting machine used by the laser cutting head design auxiliary gas pressure and nozzle size to determine, so that you can get the best air compressor and laser cutting machine matching.

Comparison of laser cutting with different auxiliary gases

Laser cutting, according to the different material of the cutting plate, to choose different cutting gas. Cutting gas and the choice of pressure, laser cutting quality has a great impact.

Laser cutting processing commonly used auxiliary gas oxygen (O2), nitrogen (N2) and Compressed Air (Compressed Air), sometimes also use argon (Ar). According to the gas pressure can be divided into high pressure gas and low pressure gas.

The role of laser cutting auxiliary gas mainly includes: combustion and heat dissipation, timely blowing off the cutting melting stains, prevent the cutting melting stains rebound into the nozzle, protect the focusing lens, etc. According to the different cutting materials, combined with the power of laser cutting machine, choose different laser cutting process, the choice of auxiliary gas is not the same. The characteristics, uses and application scope of different kinds of auxiliary gases are as follows:

(1) Oxygen (O2) is mainly used for cutting carbon steel materials. The chemical reaction heat of oxygen and iron promotes metal endothermic melting, which can greatly improve the cutting efficiency, achieve thicker material cutting, and significantly improve the processing capacity of laser cutting machine. But at the same time, due to the existence of oxygen, there will be obvious oxide film on the end face of the incision, and it will have a quenching effect on the material around the cutting surface, improve the hardness of this part of the material, and have a certain impact on the subsequent processing. Oxygen cut material cut end face black or dark yellow. General carbon steel plate using oxygen cutting, low pressure drilling, low pressure cutting.

(2) Argon (Ar) Argon is an inert gas, which can prevent oxidation and nitriding in laser cutting, and can also be used in dissolution. But argon gas price is higher than nitrogen, the general general laser cutting using argon gas is not cost-effective. Argon cutting is mainly used for titanium and titanium alloy, argon cutting end face white.

(3) Compressed Air (Compressed Air) Compressed Air can be directly provided by Air compressors. Compared with oxygen and nitrogen, it is easy to obtain and very cheap. Although air only contains about 20% oxygen, cutting efficiency is far less than oxygen cutting, but the cutting ability is close to nitrogen, air cutting efficiency is slightly higher than nitrogen cutting. The end face of the air cut is yellow. When there is no strict requirement on the surface color of material cut, compressed air is the most economical and practical choice instead of nitrogen cutting

(4) (4) Nitrogen (N2) When nitrogen is used as an auxiliary gas for cutting, nitrogen will form a protective atmosphere around the molten metal to prevent the material from being oxidized, avoid the formation of oxidation film, and achieve no oxidation cutting. But at the same time because nitrogen does not produce chemical reaction with metal, there is no reaction heat generation, cutting ability is not as good as oxygen, and nitrogen consumption of nitrogen cutting is several times larger than oxygen, cutting cost is higher than oxygen cutting. No oxidation cutting surface can be directly fused, smeared, strong corrosion resistance and other characteristics, cut end face white. Generally using nitrogen cutting stainless steel, galvanized sheet, aluminum and aluminum alloy plate, brass and other materials, with low pressure perforation, with high pressure cutting. When nitrogen cutting, the change of gas flow has a great impact on cutting. In the case of ensuring the pressure of cutting gas, it is necessary to ensure sufficient gas flow.

At present, the liquid nitrogen on the market is about 1400 yuan/ton, and the liquid nitrogen used for laser cutting needs to be used in the Duva tank. It is generally 120kg a tank, and the price of 1KG is more than 3 yuan, let's calculate by 1400 yuan/ton.

120X1.4 =168 yuan, and the specific gravity of nitrogen in standard state is 1.25kg/m3, so the maximum usage of liquid nitrogen in a tank of Dewar tank is about 120/1.25=96Nm3, and the cost of nitrogen per Nm3 is 168/96=1.75 yuan /Nm3

If a domestic brand air compressor is used to provide 16bar of compressed air and 1.27m3 per minute, the full load input power of this type of air compressor is 13.4kW.

Industrial electricity is calculated at 1.0 yuan/degree, then the air cost per m3 is: 13.4x1.0/(1.27x60)=0.176 yuan /m3, according to the actual consumption of 0.5m3 gas per minute, laser cutting machine works 8 hours a day, then the daily cost saved by air cutting compared with nitrogen cutting is: (1.75 0.176) x8x60x0. 5 = $378. If the laser cutting machine works for 300 days a year, the gas cost can be saved for a year: 378x300=113,400 yuan. Therefore, using compressed air instead of nitrogen cutting is very economical and practical.

In recent years, domestic laser cutting machine technology has a breakthrough development, and toward the direction of high power, high precision, large area. Under the background of Intelligent manufacturing in China, the industrial field has shown a trend of transformation from traditional processing to high-end manufacturing. The market size of Laser cutting in China will always maintain a trend of rapid development, which will bring great market growth space for laser air compressor.

How to choose a good laser cutting special screw air compressor is very important, for improving efficiency, cost saving is very important.