How to adjust the focus of laser cutting machine?

1. Numerical control positioning method of laser focus
CNC positioning method: use a flat and smooth white cardboard, laid on the workbench, the laser cutting head is set above it, the height of the focusing mirror from the cardboard is about 10mm smaller than the focal length size of the focusing mirror, such as the focusing mirror focal length is 127mm, then the focusing mirror is set at about 117mm from the cardboard. The CNC system sets the cutting head to move every 10mm along the X axis or Y axis, and the Z axis rises 1mm each time it moves, and the distance of 20 continuous movements can be set. When each move is in place, a total of 20 holes are punched in 20 times, and the height of the Z-axis is increased by 20mm. Observing these 20 holes, it can be found that the diameter of the holes changes from large to small, and then from small to large bamboo slips. Find the spot with the smallest aperture is the focal point, and write that down. The distance between the cardboard and the lens when measured at this position is the actual laser beam focus position.

2. Inclined focus cautery
Inclined plane focus burning method: This method is shown as follows, the flat board is placed on the workbench at an Angle of about 10 degrees. The cutting head is set at point A, and the height size of the focusing mirror from point A is 20mm smaller than the focal length size of the focusing mirror. The CNC system sets the cutting head to move 230mm horizontally continuously along the X axis or Y axis, and the laser output 200W continuous laser when the moving head stops, the laser also stops. Now you can see the burn marks of a laser beam on the board that has narrowed from wide to narrow. Take the narrowest point of the trace as the focus position, record this point, and measure the distance between the board and the lens at this position is the actual laser beam focus position. 

3. Laser cutting direct cautery method
Direct burning method: This principle is to hold a flat board, immediately in the cutting table 85 degrees Angle, the cutting head raised to the focusing mirror from the surface of the table about 1.5 times the focus position. Open the laser gate, continuously output the 200W laser beam, and quickly move the board horizontally to the bottom of the focusing mirror, you can see that the surface of the board will have a burning trace before and after the laser beam focusing from wide to narrow, and from narrow to wide, this trace is very close to the change of the laser beam focusing process. Take the narrowest point of the trace as the focus position, record this point, and measure the distance between the board and the lens at this position is the actual laser beam focus position. Because this method requires manual operation, it is especially necessary to pay attention to safety so as not to cause human injury.