Laser cutting of common engineering materials
1、Laser cutting of metal materials
Although almost all metal materials have high reflectivity to infrared energy at room temperature, the CO2 laser emitting a 10.6um beam in the far-infrared band is successfully applied to many metal laser cutting processing practices. The initial absorption rate of metal to the 10.6um laser beam is only O. 5% to 10%, but when the power density exceeds 106 ohms, the focused laser beam of cnl2 irradiates the metal surface, but it can quickly melt the surface in microseconds. The absorption rate of most metals in the molten state rises sharply, generally by 60% to 80%.
Modern laser cutting processing systems can cut carbon steel plates with a maximum thickness of up to 20 mm. The cutting seam of carbon steel can be controlled within a satisfactory width by using the oxidation melting cutting mechanism, and the cutting seam for thin plates can be as narrow as about 0.1 mm.
Laser cutting is an effective processing tool for the manufacturing industry that uses stainless steel sheet as the main component. Under strict control of the heat input in the laser cutting process, the heat-affected zone of the trimming can be restricted from becoming very small, thereby effectively maintaining the good corrosion resistance of this type of material.
Most alloy structural steels and alloy tool steels can be used to obtain good trimming quality by laser cutting. Even for some high-strength materials, as long as the process parameters are properly controlled, straight, non-sticky slag cutting edges can be obtained. However, for tungsten-containing high-speed tool steel and hot mold steel, there will be erosion and slag sticking during laser cutting.
（4）Aluminum and alloys
Aluminum cutting is a melting cutting processing mechanism, and the auxiliary gas used is mainly used to blow away the molten product from the cutting area, and usually a better cut surface quality can be obtained. For some aluminum alloys, attention should be paid to prevent the occurrence of micro-cracks between the surface of the slit.
（5）Copper and alloys
Pure copper (red copper) basically cannot be cut with a CO2 laser beam due to its high reflectivity. Brass (copper alloy) uses a higher laser power, and the auxiliary gas uses air or oxygen, which can cut thinner plates.
（6）Titanium and alloys
Pure titanium can well couple the heat energy converted by the focused laser beam. When the auxiliary gas is oxygen, the chemical reaction is fierce, and the cutting speed is faster, but it is easy to form an oxide layer on the cutting edge, and it can cause overburn if you are not careful. For the sake of safety, it is better to use air as the auxiliary gas to ensure the cutting quality.
The laser cutting quality of titanium alloy commonly used in the aircraft industry is good. Although there will be a little sticky slag at the bottom of the cutting seam, it is easy to remove.
Nickel-based alloys are also called super alloys, and there are many varieties. Most of them can be oxidized fusion cutting.
2、Laser cutting of non-metallic materials
The C02 laser beam with a wavelength of 10.6um is easily absorbed by non-metallic materials. The poor thermal conductivity and low evaporation temperature make the absorbed beam almost the entire interior of the input material, and it vaporizes instantly at the spot where it is irradiated, forming a starting hole and entering the cutting The virtuous circle of the process.
Organic materials that can be laser cut include: plastic (polymer), rubber, wood, paper products, leather, etc.
Inorganic materials that can be cut by laser include: quartz, glass, ceramics, stone, etc.
New lightweight reinforced fiber polymer composites are difficult to process by conventional methods. Using the characteristics of laser non-contact processing, the laminated sheet before curing can be cut and trimmed at a high speed, and the length of the laminated sheet can be cut and trimmed at a high speed. Under the heating of the laser beam, the edge of the sheet is fused to avoid the generation of fiber debris. For thick workpieces that are fully cured, especially boron fiber and carbon fiber composite materials, attention should be paid to the laser cutting process to prevent carbonization, delamination and thermal damage from the trimming. Just like plastic cutting, the waste gas needs to be removed in time during the cutting process of synthetic materials. There is also a type of composite material, which is simply composed of two materials with different properties. In order to obtain better cutting quality, the general principle of laser cutting is to first cut the side with better cutting properties.
Conclusion: As the earliest and most extensive application of laser technology, laser cutting processing has developed particularly rapidly at home and abroad in recent years. However, the current laser cutting field is not very extensive. In the future, laser cutting technology will develop towards high-speed and high-precision cutting. The cutting thickness will gradually increase, and it will develop from the light industry sheet to the heavy industry.