Laser cutting of metal materials
Almost all metal materials have high reflectivity to infrared ray at room temperature. For example, the CO2 laser absorption of 10.6 pum is only 0.5%~10%. However, when the focused beam with the power density exceeding 106W/cm2 shines on the metal surface, the surface will start to melt in a few microseconds. The absorptivity of most molten metals will rise sharply, generally up to 60%~80%. Therefore, CO2 lasers have been successfully used in many metal cutting practices.
The maximum thickness of carbon steel plate that can be cut by modern laser cutting system has exceeded 20mm. The oxygen assisted melting cutting method is used to cut carbon steel plates. The cut can be controlled within a satisfactory width, and the cut on thin steel plates can be narrowed to about 0.1mm. Laser cutting is an effective processing method for stainless steel plate. The heat affected zone can be controlled in a small range, so as to maintain its corrosion resistance. Most alloy structural steels and alloy tool steels can obtain good trimming quality by laser cutting.
Aluminum and aluminum alloy cannot be cut by oxygen melting, but must be cut by melting mechanism. Aluminum laser cutting needs high power density to overcome its high reflectivity to 10.6um wavelength laser. The YAG laser beam with a wavelength of 1.06um can greatly improve the cutting quality and speed of aluminum laser cutting due to its high absorption.
Titanium and titanium alloys commonly used in the aviation industry use oxygen as the auxiliary gas. The chemical reaction is violent and the cutting speed is fast, but it is easy to form an oxide layer on the cutting edge, or even cause over burning. It is safer to use inert gas as auxiliary gas to ensure cutting quality.
Most nickel base alloys can also be cut with oxygen flux. The reflectivity of copper and copper alloys is too high to cut with 10.6pm CO2 laser.
Laser cutting of non-metallic materials
10.6um CO2 laser beam is easily absorbed by non-metallic materials. Its low reflectivity and evaporation temperature make almost all the absorbed light energy enter the interior of the material, and cause evaporation to form holes in an instant, entering a virtuous circle in the cutting process. Plastic, rubber, wood, paper products, leather, natural fabrics and other organic materials can be cut by laser. However, the thickness of wood shall be limited. The thickness of wood board shall be less than 75mm, and the thickness of laminate and particle board shall be about 25mm. In inorganic materials, quartz and ceramics can be cut by laser, and the latter is suitable for controlling fracture cutting, and high power is not allowed. Glass and stone are generally not suitable for laser cutting.
Other materials that are difficult to be machined by conventional methods, such as composite materials and cemented carbides, can be cut by laser, but reasonable cutting mechanism and process parameters must be selected through experiments.
Source: Shanghai Panyun Technology
