Overview of laser cutting technology

  The laser beam is focused on a very small spot. The minimum diameter of the laser beam can be less than 0.1mm, so that the focal point can reach a high power density exceeding 106W / cm2. At this time, the heat of the beam input (converted from light energy) far exceeds the reflection, conduction, or diffusion part of the material, and the material is quickly heated to the vaporization humidity and evaporates to form holes. Along with the relatively linear movement of the beam and material, the cavity is continuously formed into narrow slit (such as 0.1mm or so). The cutting edge has little thermal influence and basically no work piece deformation. The auxiliary gas that is suitable for the cut material is also added during the cutting process. When steel is cut, oxygen is used as auxiliary gas and molten metal is used to produce exothermic chemical reaction oxidizing material, and at the same time helps to blow away the slag in the slotting. Cutting polypropylene one kind of plastics uses compressed air, cotton, paper and other flammable materials to cut inert gas. The auxiliary gas entering the nozzle can also cool the focusing lens, prevent the smoke from entering the lens seat and contaminate the lens and cause the lens to overheat.  

  The first Chinese name of the laser is called "laser" and "laet". It is the transliteration of its English name LASER. It is an acronym composed of the first letters of each word from the English Light Amplification by Stimulated Emission of Radiation. It means "stimulated emission of light amplification". The full name of the laser in English has fully expressed the main process of making lasers. The principle of laser was discovered by the famous American physicist, Einstein, as early as 1916. In 1964, according to Tsien Hsueshen, a famous scientist in China, the "light stimulated radiation" was renamed "laser". Laser application is very wide, mainly laser marking, laser welding, laser cutting, optical fiber communication, laser spectrum, laser ranging, laser radar, laser weapon, laser record, laser indicator, laser correction, laser cosmetology, laser scanning, laser mosquito killer and so on. 

  Most organic and inorganic materials can be cut by laser. In the heavy metal processing industry, many metal materials, no matter what kind of hardness it has, can be shaped without deformation. (the most advanced laser cutting system can cut the thickness of the industrial steel to be close to 20mm). Of course, for high reflectivity materials, such as gold, silver, copper, and aluminum alloy, they are also good conductors, so laser cutting is difficult and even cannot be cut. (some hard cutting materials can be cut by pulse wave laser beam. Because of the high peak power of pulse wave, the absorption coefficient of the material to the beam is instantaneous. The play is improved). Laser cutting has no burr, high wrinkle and high accuracy. It is superior to plasma cutting. For many mechanical and electrical industries, the modern laser cutting system can easily cut different shapes and sizes of the work piece (the work piece drawings can be modified). It is often preferable to the punching and molding process. Although it is slower than die, it has no mold consumption and no need to repair the mold. It also saves time to replace moulds thereby saving processing costs and reducing product costs, so it is economically more cost-effective in general.    

  On the other hand, laser cutting can also play the advantage of accuracy and reproducibility from how to adapt the die to the size and shape of work piece. As a prioritize tool for laminated dies, laser cutting costs are not expensive because of no need for advanced mold makers, so it can also significantly reduce the cost of mold manufacturing. The additional advantage of laser cutting die is that the cutting edge of the die will produce a shallow hardening layer (heat affected zone) to improve the wear resistance of the die. The non-contact characteristic of laser cutting brings the stress free advantage to the circular saw blade cutting forming, thereby improving the service life.   

  Laser cutting of commonly used engineering materials 

  1. Laser cutting of metal materials, although almost all metal materials have high reflectance on the infrared wave energy at room temperature, the light pumped ND:YAG laser and 10.6 mCO2 laser at the far infrared band are successfully applied to the laser cutting practice of many metals. 

  2. The laser cutting of a non-metallic material by laser cutting 10.6μm wavelengths is easily absorbed by non-metallic materials. The low thermal conductivity and low evaporation temperature make the absorbed beam almost the whole input material and vaporize at the spot irradiation, forming a starting hole and entering a virtuous cycle of the cutting process.