The Main Process Of Laser Cutting Machine

1. Vaporization cutting
During the laser gasification cutting process, the surface temperature of the material rises to the boiling point temperature so fast that it is enough to avoid melting caused by heat conduction, so part of the material is vaporized into steam and disappears, and part of the material is ejected from the bottom of the slit by the auxiliary gas The flow blows away. Very high laser powers are required in this case.
To prevent material vapor from condensing on the kerf walls, the thickness of the material must not greatly exceed the diameter of the laser beam. This process is therefore only suitable for applications where a discharge of molten material has to be avoided. This machining is practically only used in small areas of use for iron-based alloys.
This process cannot be used for materials, such as wood and certain ceramics, which do not have a molten state and are therefore less likely to allow the material vapor to recondense. Additionally, these materials typically achieve thicker cuts. In laser vapor cutting, optimal beam focusing depends on material thickness and beam quality. Laser power and heat of vaporization have only a certain influence on the optimal focus position. When the thickness of the plate is constant, the maximum cutting speed is inversely proportional to the gasification temperature of the material. The required laser power density is greater than 108W/cm2 and depends on the material, cutting depth and beam focus position. In the case of a certain thickness of the plate, assuming that there is sufficient laser power, the maximum cutting speed is limited by the speed of the gas jet.
2. Melting cutting
In laser fusion cutting, the workpiece is partially melted and the molten material is ejected by means of airflow. Because the transfer of the material occurs only in its liquid state, the process is called laser fusion cutting.
The laser beam coupled with high-purity inert cutting gas drives the molten material out of the kerf, but the gas itself does not participate in the cutting. Laser fusion cutting can achieve higher cutting speed than gasification cutting. The energy required for gasification is generally higher than that required to melt the material. In laser fusion cutting, the laser beam is only partially absorbed. The maximum cutting speed increases with the increase of laser power, and decreases almost inversely proportional to the increase of sheet thickness and material melting temperature. In the case of a certain laser power, the limiting factor is the air pressure at the kerf and the thermal conductivity of the material. Laser melting cutting can obtain oxidation-free cuts for iron materials and titanium metals. The laser power density that produces melting but less than gasification is between 104W/cm2 and 105W/cm2 for steel materials.
3. Oxidation melting cutting (laser flame cutting)
Fusion cutting generally uses inert gas. If it is replaced by oxygen or other active gas, the material is ignited under the irradiation of the laser beam, and a violent chemical reaction occurs with oxygen to generate another heat source, which further heats the material, which is called oxidation melting cutting. .
Due to this effect, higher cutting rates can be obtained with this method than with fusion cutting for the same thickness of structural steel. On the other hand, this method may have poorer cut quality than fusion cutting. It actually produces wider kerfs, noticeable roughness, increased heat-affected zone, and poorer edge quality. Laser flame cutting is bad for precision models and sharp corners (danger of burning off sharp corners). Lasers in pulsed mode can be used to limit thermal effects, and the power of the laser determines the cutting speed. In the case of a certain laser power, the limiting factors are the supply of oxygen and the thermal conductivity of the material.
4. Control fracture cutting
For brittle materials that are easily damaged by heat, high-speed and controllable cutting is performed by laser beam heating, which is called controlled fracture cutting. The main content of this cutting process is that the laser beam heats a small area of brittle material, causing a large thermal gradient and severe mechanical deformation in this area, resulting in the formation of cracks in the material. As long as a uniform heating gradient is maintained, the laser beam can direct cracks in any desired direction.