Q: How does the fiber laser cutting machine produce the slit slope when processing thick metal plates?

A: When processing thick metal plates, as the thickness of the workpiece increases, the processing accuracy of the fiber laser cutting machine becomes lower, the slit becomes larger, and the verticality of the slit also decreases, showing a slope. The slit slope of metal fiber laser cutting machines is mainly affected by two aspects: the focal length and focal position of the processing lens.

The slit width will vary due to the focusing characteristics of the laser beam on the surface of the processing material and the setting accuracy of the focus.

The effect of the processing lens distance on the slope

The figure shows the relationship between the focal distance of the processing lens and the slope. The data shown are: the upper width (U), bottom width (L), and slope (T) of the slit when processing under CW conditions and pulse conditions.

The shorter the focal distance of the lens, the smaller the diameter of the focal point, and the smaller the upper slit width and slope.

The focal position is the distance from the laser focus to the workpiece surface, which directly affects the roughness of the cut surface, the slope and width of the cut seam, and the adhesion of the molten residue.

The influence of the focal position on the slope size

The figure shows the relationship between the focal position and the slope. The focal position Z is z=o when it is on the surface of the processed material. The moving distance (h) is expressed in millimeters (mm), with positive (+) upward and negative (-) downward. When the focal position is set on the surface of the processed material (z=0), the upper cut seam width and slope are both minimum; the slope will increase when the focal position moves up or down.

The principle of this slope expansion is shown in the figure. When the focal position deviates from the material surface, the diameter of the beam irradiated to the material surface will expand, the melting range will also increase accordingly, and the slope will increase accordingly.