Vaporization Cutting Principle in Laser Cutting

When a high power density laser irradiates the workpiece surface, the material is heated to the vaporization point in a very short time, and some of the material is converted into vapor to escape and form a slit. Its power density is generally 108 W/cm2, which is 10 times the energy required by laser melting and cutting mechanism. It shows the cutting methods adopted by most mailing materials and ceramics. The vaporization cutting mechanism can be described as follows:

1. When the laser beam irradiates the surface of the workpiece, the energy part of the beam is reflected and the remaining part is absorbed by the material. The reflectivity decreases with the surface heating.

2. The surface temperature of the workpiece rises rapidly to the boiling point temperature of the material, which is enough to avoid melting caused by heat conduction.

3. Steam escapes rapidly from the workpiece surface at near sound speed. Its accelerating force generates stress wave in the material, which blocks the power density to a certain extent. The reflection of stress wave in the material will lead to the fragmentation of brittle material. At the same time, it also increases the front pressure of politics and law and the vaporization temperature.

4. Steam carries away melting particles and washes them into holes. During the vaporization process, 60% of the materials are removed in the form of droplets.

5. When the power is greater than a certain value, a stress field similar to the point load is formed, and the stress wave is reflected inside the material.

6. If overheating occurs, the hot vapor from the hole will reflect and absorb the incident laser beam due to the high electron density. There is an optimum working density. For stainless steel, beyond this value, the vapor absorption blocks the increased power and the absorption wave begins to move away from the workpiece surface towards the beam direction.

7. For some locally permeable materials, heat is absorbed internally, boiling occurs in the front of evaporation, and material is removed by explosion under the surface.