Negative focal length: Because the cutting point of the fiber laser cutting machine is neither on the surface nor inside the workpiece, but is located above the cutting material, this method is also called negative focal length.

Generally, this focus is used because the thickness of the plate is relatively high. If the focus is not located in this way, it may cause insufficient oxygen delivered by the nozzle, resulting in a drop in cutting temperature and failure to cut the material. However, a significant disadvantage of this method is that the cutting surface is rough and not suitable for precision cutting.

Positive focal length: This method is called positive focal length, and it is generally used when the fiber laser cutting machine cuts stainless steel or aluminum steel plates and other materials, so that the cutting focus is located inside the workpiece.

The main disadvantage of this method is that the cutting range is relatively large, and this mode often requires a stronger cutting airflow, sufficient temperature, and longer cutting and perforation time. Therefore, it is only used when cutting hard materials such as stainless steel or aluminum.

Zero focal length: This mode is the most common focal position, also known as 0 focal length, and is often used to cut workpieces such as SPC/SPH/SS41. When using it, let the focus of the fiber laser cutting machine be close to the surface of the workpiece.

In this mode, due to the slight difference in the smoothness of the upper and lower surfaces of the workpiece, the cutting surface close to the focus is often smoother, and conversely, the cutting surface far from the focus is rougher. In actual use, it is often determined according to the different process requirements of the upper and lower surfaces.

In summary, when using the fiber laser cutting machine, we choose different focus modes according to the processing needs of different workpieces, which can give full play to the performance advantages of the fiber laser cutting machine and ensure the cutting effect.