After determining which focal length lens to use, the relative position of the focus to the surface of the workpiece is especially important to ensure the quality of the cut. Since the power density is highest at the focus, in most cases, the focus position at the time of cutting is just right on the surface of the workpiece or slightly below the surface.

Therefore, ensuring a constant relative position of the focus and the workpiece throughout the cutting process is an important condition for obtaining a stable cutting quality. Sometimes the lens is heated due to poor cooling and causes a change in focal length, which requires us to adjust the focus position in time.

In most applications, the beam focus should be adjusted just below the nozzle. The distance between the laser cutter china nozzle and the workpiece surface is typically about 1.5 mm.

When the focus is in the best position, the slit is the smallest and the efficiency is the highest. The best cutting speed of the laser cutter china can get the best cutting result.