Relationship between metal cutting process and light spot！

Light spot and metal cutting processLaser cutting uses a focused high-power density laser beam to irradiate metal materials. The irradiated metal materials quickly melt, vaporize, ablate or reach the ignition point, and then use the high-speed airflow coaxial with the beam to blow away the molten material, thereby cutting the workpiece. However, when the thickness of the laser cutting plate is large, such as more than 5mm, the beam will be reflected multiple times at the front and side of the slit, and because the inclination angle of the bottom of the slit increases, the absorption of the laser at the bottom reflection point also increases, which can easily cause local overheating in the middle and lower part of the front of the slit.

Taking the cutting section of thick plate carbon steel as an example, the cutting section can be divided into three areas:

Top layer: the area where the beam directly penetrates, showing fine and vertical stripes;

Middle layer: shelf-like area, most of the beam is absorbed by the material in this area;

Bottom layer: flushing area, the overheated molten material flows out of the slit from this area, and takes away more molten material.

Due to the multiple reflections of the laser in the middle layer of the slit, local overheating will eventually lead to rough cutting sections and even defects similar to bullet holes. For carbon steel cutting, defects are generally generated in the middle layer.

The cutting ability of the laser is closely related to the laser energy distribution. Common forms of laser energy distribution include Gaussian, flat top, and the latest ring. The low energy density at the center of the ring spot can reduce bullet hole-like cutting defects and improve the thick plate cutting ability (including cutting speed and cutting quality). At the same time, on this basis, the use of a 50μm fiber core diameter can improve the cutting ability of thin plates. Therefore, by optimizing the laser energy distribution, the cutting ability of metal thin plates and thick plates can be greatly improved.

Better cutting quality of thick plate carbon steel Cutting of thick carbon steel plates has always been a difficult point in the application of fiber lasers in cutting. There are many factors that affect carbon steel cutting. In addition to gas purity, cutting head collimation and focusing characteristics, nozzle type, etc., the energy distribution of the laser beam focal plane spot also has an important influence. After optimizing the spot energy distribution, the cutting section quality of carbon steel plates with a thickness of 20mm and above has been greatly improved.

Related product links

CO2 Laser Cutting Machine