How to Avoid Metal Laser Cutting Occurs Over Burning?

When we cut metal materials by fiber laser cutting machine occurs over burning. What should I do?

We know Laser cutting focuses laser beam on the material surface to melt it, and at the same time, compressed gas collimated with the laser beam is used to blow away the molten material, while the laser beam is moving with the material relative to a certain trajectory to form a certain shape of cutting slot.

Below process is continuously repeated to achieve the purpose of fiber laser cutting metal.

1. Laser beam focus on materials

2. The materials absorb the laser power and melt imemiditly

3. The materials burning with oxygen and melt deeply

4. Melted materials was blower out by oxygen pressure

The causes affecting over burning as below:

1. Material surface. Carbon steel exposed to air will oxidize and form oxide skin or oxide film on the surface. The thickness of this layer/film is uneven or the film is not tightly attached to the plate, which will lead to uneven absorption of laser by the plate and unstable heat generation.This affects the second step of the above cutting process.

Before cutting, try to choose the surface with good surface state facing up.
2. Heat accumulation. Good cutting state should be that the heat generated by laser irradiation on the material and the heat generated by oxidation combustion can be effectively dissipated, and cooling is effectively carried out. If cooling is insufficient, it may cause burning.
When processing trajectory involves multiple small shapes, heat will continuously accumulate with the cutting process, which is easy to cause burning when cutting to the later part.

To solve this problem, it is better to scatter the processing pattern as much as possible, so as to effectively scatter heat.
3. Sharp corners burning. Carbon steel exposed to air will oxidize and form oxide skin or oxide film on the surface. This layer/film thickness is uneven or the film is not tightly attached to the plate, which will lead to uneven absorption of laser by the plate and unstable heat generation. This affects the second step of the above cutting process.

Before cutting, try to choose the surface with good surface state facing up.
The occurrence of burning at sharp corners is usually caused by heat accumulation because the temperature at this angle has already risen to a very high level when the laser beam passes through it.

If the speed of laser beam is greater than the heat conduction speed, burning can be effectively avoided.