1. Vaporization cutting
  & nbsp; In the process of laser vaporization cutting, the rate at which the surface temperature of the material rises to the boiling point temperature is so fast that it can avoid melting caused by thermal conduction. As a result, some of the material vaporizes into steam and disappears, while others are blown away as ejecta from the bottom of the cutting seam by the auxiliary gas flow. In this case, a very high laser power is required. To prevent material vapor from condensing onto the slit wall, the thickness of the material must not exceed the diameter of the laser beam significantly. This processing is therefore only suitable for applications where it is necessary to avoid the exclusion of molten materials. This processing is actually only used in a small application area of iron-based alloys.
  & nbsp; This processing cannot be used for materials such as wood and certain ceramics that are not in a molten state and therefore are unlikely to allow the material vapor to re condense. Additionally, these materials typically require thicker incisions. In laser vaporization cutting, the optimal beam focusing depends on the material thickness and beam quality. The laser power and gasification heat have only a certain impact on the optimal focal point position. When the thickness of the board is constant, the maximum cutting speed is inversely proportional to the gasification temperature of the material. The required laser power density should be greater than 108W/cm2 and depends on the material, cutting depth, and beam focal position. Given a constant thickness of the sheet, assuming sufficient laser power, the maximum cutting speed is limited by the gas jet velocity.
2. Melting cutting
  & nbsp; In laser melting cutting, the workpiece is locally melted and the melted material is sprayed out by air flow. Because the transfer of materials only occurs in their liquid state, this process is called laser melting cutting.
  & nbsp; The laser beam combined with high-purity inert cutting gas promotes the melted material to leave the cutting seam, while the gas itself does not participate in cutting. Laser melting cutting can achieve higher cutting speeds than gasification cutting. The energy required for gasification is usually higher than the energy required to melt the material. In laser melting cutting, the laser beam is only partially absorbed. The maximum cutting speed increases with the increase of laser power, and decreases almost inversely proportional with the increase of plate thickness and material melting temperature. Under a constant laser power, the limiting factor is the air pressure at the slit and the thermal conductivity of the material. Laser melting cutting can obtain non oxidizing cuts for iron materials and titanium metals. The laser power density that produces melting but not gasification is between 104W/cm2 and 105 W/cm2 for steel materials.
3. Oxidation melting cutting (laser flame cutting)
  & nbsp; Melting cutting generally uses inert gases. If oxygen or other active gases are used instead, the material is ignited under the irradiation of a laser beam, and a violent chemical reaction occurs with oxygen to produce another heat source, which further heats the material, known as oxidation melting cutting.
  & nbsp; Due to this effect, for structural steel of the same thickness, the cutting rate obtained using this method is higher than that of melting cutting. On the other hand, this method may result in poorer incision quality compared to melt cutting. In fact, it will generate wider cuts, noticeable roughness, increased heat affected zone, and poorer edge quality. Laser flame cutting is not good for processing precision models and sharp corners (there is a risk of burning off sharp corners). Pulse mode lasers can be used to limit thermal effects, and the power of the laser determines the cutting speed. Under a constant laser power, the limiting factors are the supply of oxygen and the thermal conductivity of the material.
4. Control fracture cutting
  & nbsp; For brittle materials that are prone to thermal damage, high-speed and controllable cutting through laser beam heating is called controlled fracture cutting. The main content of this cutting process is to heat a small area of brittle material with a laser beam, causing a large thermal gradient and severe mechanical deformation in that area, resulting in the formation of cracks in the material. As long as a balanced heating gradient is maintained, the laser beam can guide cracks to occur in any desired direction.