The distance between the focal point and the surface of the board is 2-3mm above the board; The cutting head adopts a lens focal length of 7.5 inches.

General laser cutting machines cannot cut holes smaller than the thickness of the plate, as energy accumulates in the cross-sectional layer of the plate, making it difficult for waste materials to fall off.

The relationship between laser cutting focal length and thickness: This depends on the cutting material, as explained below:

1. Negative focal length (the cutting focus is located on the cutting material) is mainly used when cutting thick metal plates. Negative focal length cutting of thick plates requires a large cutting amplitude, which leads to insufficient oxygen delivery to the nozzle, resulting in a decrease in cutting temperature. The cutting surface is relatively rough and not suitable for high-precision precision cutting.

2. 0 focal length (the cutting focus is located on the surface of the cutting material) is usually a focus positioning method suitable for cutting materials such as SS41, SPH, SPC, etc. The focus of zero focal length cutting is close to the surface of the workpiece. Due to the different smoothness of the cutting surface, the upper surface is relatively smooth during cutting, while the lower surface appears relatively rough. This method of cutting focus positioning needs to be determined based on the actual process requirements of the upper and lower surfaces.

3. Internal negative focal length (the cutting focus is located inside the cutting material) is usually applied to fiber laser cutting machines in cutting materials such as aluminum, aluminum alloys, and stainless steel. According to the principle of focus, the surface is cut with a relatively large cutting amplitude relative to the cutting point on the workpiece surface. In this mode, using a fiber laser cutting machine produces a larger airflow, higher temperature, and slightly longer cutting time for perforation. So this cutting method is mainly used in cutting materials with high hardness such as aluminum or stainless steel.