The power density at the focal point of the laser can be as high as 107W/cm2 to 40,000W/cm2, and the temperature can be as high as 10,000°C. It is an ideal cutting heat source, can make any hard materials such as ceramics, cemented carbide, diamond, etc., will be instantaneous local melting and evaporation. And through the strong shock wave generated by the eruption. Therefore, we can utilize lasers for cutting and other processing of various materials.And now let’s unveil the superior effects of laser cutting on ceramics.
1.Principle of Laser Cutting
Laser cutting system uses a focused high power density laser beam to irradiate the workpiece. So that the irradiated place of the material immediately melt, vaporization, ablation or reach the ignition point. At the same time borrow and beam coaxial high-speed airflow to blow away the molten material, thus realizing the workpiece cut a thermal cutting method. (High-speed gas flow : that is, with a certain pressure of the auxiliary gas, commonly used gases such as N2, O2, air. Its main role is: in melting cutting, relying on the pressure of the blowing gas to blow away the liquid metal to form a cut. In oxygen cutting, gas and cutting metal reaction exothermic to provide part of the cutting energy, while relying on the gas to blow away the reactants).
2.Pros of Laser Cutting
- Good cutting quality: due to the laser’s small spot, high energy density, cutting speed and fast, so can get good cutting quality.
- Narrow slit: laser cutting slit is generally 0.10 ~ 0.20mm, saving material.
- Good verticality of the cutting edge: the cutting surface is smooth and burr-free, and the surface roughness is generally controlled at Ra:12.5 or more.
- Heat-affected zone is small: laser processing laser slit fine, fast, concentrated energy, so the heat transferred to the cut material is small, caused by the deformation of the material is also very small, in some occasions, the width of the heat-affected zone in the following 0.05mm.
- Can cut a variety of materials: can cut both metal materials and can cut a variety of non-metallic materials.
- Cutting torch and other non-contact with the workpiece: no tool wear problems, easy to realize unmanned automatic control, improve cutting efficiency.
- Good cutting environment: there is no strong radiation, noise and environmental pollution during cutting, creating a good workplace for the operator’s health.
3.Features of Ceramic Materials
Ceramics is currently the fastest growing inorganic non-metallic materials, it is by a variety of metals with oxygen, nitrogen or carbon and other synthetic. It has the advantages of high hardness, oxidation resistance, wear resistance, high temperature resistance, corrosion resistance, low coefficient of friction, small coefficient of thermal expansion and light density, etc. It is a good material for mechanical parts and cutting blades.
However, it almost does not show plastic deformation at room temperature, the processing surface is easy to produce cracks, corners are easy to collapse, these cracks left on the surface will lead to the reduction of its physical properties; at the same time, because of the hard and brittle material, the processing of the tool wear and tear is serious, the material removal rate is low, affecting the machining efficiency, and therefore want to use the general method of ceramic materials processed into a precise geometry, high dimensional accuracy and form precision, low surface roughness and high precision, low surface roughness. Therefore, it is very difficult to machine ceramic materials into parts with precise geometry, high dimensional and positional accuracy, and low surface roughness by general methods.
4.Cutting Features of Ceramics Are Perfectly Matched to the Laser
(1) High absorption of laser light
Even the longer wavelength of the CO2 laser, ceramic absorption rate is much higher than the general metal. Such as Aluminum Oxide (Al2O3) ceramic absorption rate of about 85%, Zirconium Oxide (Zr O2) is up to 90% or so, Silicon Nitride (Si3N4) and Silicon Carbide (Si C) ceramics absorption rate is also more than 40%, if the surface of the ceramic is rougher, the absorption rate is further increased, are in more than 90%.
(2)Decomposition and sublimation by high temperature irradiation
Such as Silicon Nitride (Si3N4) and Silicon Carbide (Si C) ceramics in the high temperature heating with decomposition and sublimation properties. Therefore, once irradiated by a high energy density laser beam, localized decomposition and sublimation will occur, helping to improve the efficiency of laser cutting machine processing.
