Laser cutting is to focus the laser beam on the material surface with a focusing mirror to melt the material, at the same time, use compressed gas coaxial with the laser beam to blow away the melted material, and make the laser beam and the material move relative along a certain trajectory, thus forming a certain shape of slit.
Causes affecting overburn
1. Material surface
Carbon steel will oxidize when exposed to air and produce scale or oxide film on the surface. If the thickness of this film/skin is uneven or the film/skin is not lifted close to the plate, the laser absorption of the plate will be uneven, and the heat generated will be unstable. This affects the ② step of the above cutting. Before cutting, try to place it with the good surface facing up.
2. Heat accumulation
A good cutting state should be: the heat generated by laser irradiation of materials and the heat generated by oxidation combustion can effectively diffuse to the surrounding, and can be effectively cooled. If the cooling is not sufficient, it may cause overburn.
When the machining path involves multiple small shapes, the heat will accumulate continuously with the cutting process, and it is easy to overburn when cutting to the second half.The solution is to disperse the processing graphics as much as possible, so that the heat can be effectively dispersed.
3. Burn at sharp corners
Carbon steel will oxidize when exposed to air and produce scale or oxide film on the surface. If the thickness of this film/skin is uneven or the film/skin is not lifted close to the plate, the laser absorption of the plate will be uneven, and the heat generated will be unstable. This affects the ② step of the above cutting. Before cutting, try to place it with the good surface facing up.
The overburn at the sharp corner is usually caused by heat accumulation, specifically because the temperature at the sharp corner has risen to a very high level when the laser passes by. If the forward speed of the laser beam is greater than the heat transfer speed, it can effectively avoid overburn.
How to solve over burning?
In general, the heat conduction speed during overburning is 2m/min. When the cutting speed is greater than 2m/min, melting loss will not occur. Therefore, the use of high-power laser cutting can effectively prevent over burning.
Source: Guanghui Laser
