Although almost all metal materials have high reflectance to the infrared wave energy at room temperature, the CO2 laser, which is in the far infrared 10.6um beam, has been successfully applied to the laser cutting practice of many metals. The initial absorptivity of metal to 10.6um laser beam is only 0.5%~10%. However, when a focused laser beam with a power density of more than 106w/cm2 reaches the metal surface, it can melt the surface rapidly within microsecond time. The absorption rate of most metals in molten state increases rapidly, generally increasing 60%~80%.
What are the common engineering materials for cutting metal laser cutting machines?
(1) Carbon steel. Modern laser cutting equipment can cut carbon steel plates with a maximum thickness of 20MM. The cutting seam of carbon steel can be controlled in a satisfactory width range by oxidizing and melting cutting mechanism, and the slit can be narrowed to about 0.1MM.
(2) Stainless steel. Laser cutting machine is an effective processing tool for manufacturing industry using stainless steel sheet as the main component. Under strict control of heat input in laser cutting process, the heat affected zone of trimming can be restricted to be very small. Therefore, it is very effective to maintain good corrosion resistance of such materials.
(3) Alloy steel. Most alloy structural steels and alloy tool steels can obtain good edge cutting quality by means of laser cutting machine. Even with some high strength materials, straight and sticky slag trimming can be obtained as long as the process parameters are properly controlled. However, for high speed tool steels and hot die steels containing tungsten, there will be erosion and slag sticking during laser cutting.
(4) Aluminum and alloy. Aluminum cutting is a melting and cutting mechanism. Auxiliary gas is used to blow away the molten products from the cutting area. The better quality of the tangent is usually obtained. For some aluminum alloys, it is necessary to prevent the occurrence of intergranular micro cracks on the surface of the slit.
(5) Copper and alloy. Pure copper (copper) can not be cut by CO2 laser beam because of its high reflectivity. Brass (copper alloy) uses higher laser power and auxiliary gas uses air or oxygen to cut thinner plates.
(6) Titanium and alloy. Pure titanium can be well coupled to focus the heat energy transferred by the laser beam. When the auxiliary gas is used in oxygen, the chemical reaction is intense and the cutting speed is fast. However, it is easy to form oxide layer on the side of the cut. In order to be safe, it is better to use air as auxiliary gas to ensure the quality of cutting. The laser cutting quality of titanium alloy commonly used in aircraft manufacturing industry is better. Although there is a little slag on the bottom of the slit, it is easy to remove.
(7) Nickel alloy. Nickel based alloys, also known as superalloys, have a wide variety of varieties. Most of them can be oxidized and melted.