The quality of laser cutting processing refers to the accuracy of cutting dimensions and the quality of the cutting surface. The quality of the cutting surface is generally measured by the following four indicators: the width of the incision and the surface roughness of the incision; the width of the heat-affected zone; the corrugation of the incision section ; Whether there is slag on the cut section or on the lower surface. The main factors affecting the surface quality of laser cutting are as follows:
1. For cutting laser, the laser should have high beam quality. Laser cutting is a process based on thermal effects. In order to obtain high power density and fine incision, the diameter of the focused spot should be small. At the same time, in order to ensure the consistency of quality when cutting in different directions, the laser beam should have good rotational symmetry around the optical axis. and circular polarization, as well as high emission direction stability, to ensure that the focused spot position is stable and unchanged. Modern lasers should also feature fast switching between continuous and high-repetition outputs to ensure high-quality cuts of complex contours.
2. The thickness of the focusing lens and the sheet, the focal length of the lens is selected according to the thickness of the material to be cut, taking into account the diameter of the focusing spot and the depth of focus, the material is thick, and the focal length should be large, otherwise, the focal length should be small. The position of the focusing spot should be close to the surface of the workpiece, and generally the focus should fall on the upper surface of the plate about 1/3 of the thickness of the plate.
3. Air flow and nozzle, the air flow in the laser cutting machine has the function of blowing off the molten material, protecting the focusing lens and even providing part of the cutting energy. Gas pressure and flow are important factors affecting the cutting quality. If the pressure is too low, the molten material at the incision cannot be blown away; if the pressure is too high, it is easy to form eddy currents on the surface of the workpiece, which weakens the effect of the airflow to remove the molten material. Practice has proved that nozzles with different structures will also have different effects on cutting.
4. The cutting speed of laser cutting outsourcing processing depends on the power density of the laser and the thermophysical properties and thickness of the material to be cut. Under certain cutting conditions, there is a reasonable cutting speed range. If the cutting speed is too high, the incision will not be cleaned completely, or even cut through. If the cutting speed is too low, the material will be over-burned, and the width of the incision and the heat-affected zone will be large.
5. Cutting trajectory, for the cutting of complex contours or parts with inflection points, due to the change of acceleration, it is easy to overheat and melt at the inflection point to form a slump, so a reasonable cutting trajectory is one of the effective ways to avoid this phenomenon.