Judging the cutting quality of a laser cutting machine is the most direct and best way to determine the performance of laser cutting equipment. Here are nine criteria for judgment.
1. Surface Roughness. Laser cutting creates vertical grooves on the cut surface. The depth of these grooves determines the surface roughness; shallower grooves result in a smoother cut. Roughness affects not only the appearance of the edges but also the frictional properties. In most cases, it is necessary to minimize roughness, so shallower grooves lead to higher cutting quality.
2. Perpendicularity. For sheet metal exceeding 10mm in thickness, the perpendicularity of the cutting edge is crucial. As the laser beam moves away from the focal point, it diverges, causing the cut to widen towards the top or bottom depending on the focal point's location. The more percentile the cutting edge deviates from the vertical line (by a few millimeters), the higher the cut quality.
3. Cutting Width. Generally, the kerf width does not affect the cutting quality. It only has a significant impact when forming particularly precise contours within the part, as the cutting width determines the minimum inner diameter of the contour. As the sheet metal thickness increases, the cutting width also increases. Therefore, to ensure the same high precision, regardless of the kerf width, the workpiece's processing area within the laser cutting machine should remain constant.
4. Texture. When cutting thick plates at high speed, molten metal does not appear in the cut below the vertical laser beam; instead, it is ejected from behind the laser beam. As a result, curved textures are formed at the cutting edge, closely following the moving laser beam. To correct this problem, reducing the feed rate at the end of the cutting process can greatly eliminate the formation of textures.
5. Burrs. The formation of burrs is a very important factor that determines the quality of laser cutting. Because the removal of burrs requires additional work, the severity and quantity of burrs can be directly used to judge the quality of the cut.
6. Material Deposition. Before the laser cutting machine begins melting and perforating, it first applies a layer of special oil-containing liquid to the workpiece surface. During the cutting process, due to vaporization and the different materials involved, the customer blows away the cut with air, but even if the air is blown upwards or downwards, it will still leave a deposit on the surface.
7. Dents and corrosion. Dents and corrosion have an adverse effect on the surface of the cut edges, affecting the appearance. They occur in cutting errors that should generally be avoided.
8. Heat-Affected Zone (HAZ). During laser cutting, the area near the cut is heated. Simultaneously, the metal's structure changes. For example, some metals undergo hardening. The HAZ refers to the depth of the region where the internal structure has changed.
9. Deformation. If cutting causes the part to heat up rapidly, it will deform. This is especially important in precision machining, where contours and connecting pieces are often only a few tenths of a millimeter wide. Controlling laser power and using short laser pulses can reduce part heating and prevent deformation.
