How to adjust the laser focus?

1. Cutting the focus on the surface of the workpiece

This method called 0 focal length. It is commonly use in SPC, SPH, SS41 and other workpiece cutting. When used, the focus of the cutting machine selected close to the surface of the workpiece. In this mode, the smoothness of the upper and lower surfaces of the workpiece is different. The near-focus cutting surface is relatively smooth, while the lower surface away from the cutting focus appears rough. This mode should based on the process requirements of the upper and lower surfaces in the actual application.

2, the cutting focus is inside the workpiece

This method is also called positive focal length. When the workpiece is stainless steel or aluminum steel. The pattern of cutting points inside the workpiece often use. However, one disadvantage of this method is that the cutting surface is larger than the cutting point on the surface of the workpiece. It  due to the focus principle. At the same time, the cutting airflow required in this mode is large. The temperature is sufficient, and the cutting perforation time is slightly longer. Therefore, when the material of the workpiece is mainly stainless steel or aluminum.

3, cutting focus on the workpiece

This approach refer to as the negative focal length because the cutting point is not locat on the surface of the cutting material nor inside the cutting material, but rather above the cutting material. This method mainly uses materials with high cutting thickness. The reason why this way of focus on the top of the cutting material is mainly because the thick plate needs a large cutting width, otherwise the oxygen deliver by the nozzle is very likely to cause insufficientness and the cutting temperature is lowered. One disadvantage of this approach, however, is that the cut surface is rough and not very useful for high precision cuts.

How to focus the laser cutting head?

1. Printing method: the cutting head moves from top to bottom, and the laser beam printed on the plastic plate, and the minimum diameter of the printing is the focus.

2. Slanting plate method: use a plastic plate placed at an angle to the vertical axis to pull it horizontally, and find the minimum point of the laser beam as the focus.

3, blue spark method: remove the nozzle, blow the air, the pulse laser on the stainless steel plate, so that the cutting head moves from top to bottom, until the blue spark is the focus. Through the summary analysis of the Daikin laser, in general, the focus position of the laser cutting machine should be on the surface of the workpiece or slightly lower, but different material requirements are different. When cutting carbon steel, the cutting quality is better when the focus is on the surface of the sheet. The focus should be better at about 1/2 of the thickness of the sheet.