Analysis of Quality Evaluation Criteria for Laser Cutting Machine Processing

A laser cutting machine system is generally composed of a laser generator, (external) beam transmission components, a worktable (machine tool), a microcomputer numerical control cabinet, a cooler, and a computer (hardware and software), etc. Cutting accuracy is the first factor in judging the quality of a CNC laser cutting machine.

In the laser cutting process of general materials, due to the relatively high cutting speed, the thermal deformation of the parts is very small. The dimensional accuracy of the cut parts mainly depends on the mechanical accuracy and control accuracy of the worktable of the laser cutting machine. In pulsed laser cutting processing, high-precision cutting devices and control technologies are adopted, and dimensional accuracy can reach the micrometer level.

So, what are the criteria for evaluating the processing quality of laser cutting machines?

There is still no unified international standard for the quality evaluation of laser cutting. The main basis for testing the quality of laser cutting is JIS and WES (Welding Specifications). There are standardization issues regarding laser cutting in CEN (European Organization for Standardization) and ISO (International Organization for Standardization). The ISO9000 series of quality assurance methods mainly provided by the EU have conducted research on laser cutting standards and standard sample regulations, etc. The contents include: classification of cutting quality grades, standards for setting samples and processing samples, optical systems, machine types of price samples and beam characteristics, etc.

The main principles for evaluating the quality of laser cutting processing

The laser cutting machine must cut smoothly without stripes or brittle fractures. The width of the slit is narrow and is related to the diameter of the laser beam spot. The perpendicularity of the cut seam is good and the heat-affected zone is small. There is no burning of material, no formation of a molten layer, and no large slag. The surface roughness of the cut, the magnitude of the surface roughness, is the key to measuring the surface quality of laser cutting. In addition, the state of the molten layer during the processing and the final formation directly affect the quality evaluation of laser cutting processing.

2. Standards for measuring the cutting quality of laser cutting machines

The standards for evaluating the cutting quality of a laser cutting machine include: surface roughness Rz of the cutting surface, size of slag hanging on the cut edge, verticality and slope u of the cut edge, fillet size r of the cutting edge, trailing amount n of the stripe, and flatness F. With the development of laser cutting technology, the application fields of laser cutting are becoming increasingly extensive, and the applicable materials are also growing. However, different materials have different properties, so the matters needing attention when using laser cutting also vary.

3. Factors Affecting the cutting Quality of laser cutting machines

The size of the laser condensation in the laser generator of the laser cutting machine. If the light spot is very small after aggregation, the cutting accuracy will be very high, and the gap after cutting will also be very small. This indicates that the precision of the laser cutting machine is extremely high and its quality is also very high. The precision of the worktable: If the precision of the worktable is very high, the cutting precision will also be improved accordingly. The laser beam condenses into a conical shape. The different materials being cut will also affect the precision of the laser cutting machine.

4. Influencing factors of surface roughness in laser cutting

The inherent parameters of the cutting system of the laser cutting machine, such as the spot mode and focal length, etc. Adjustable process parameters during the cutting process, such as power size, cutting speed, type and pressure of auxiliary gas, etc. The physical property parameters of the processed materials, such as the absorption rate of laser, melting point, viscosity coefficient of molten metal oxide, surface tension of metal oxide, etc. In addition, the thickness of the processed part also has a significant impact on the surface quality of laser cutting. Relatively speaking, the smaller the thickness of the metal workpiece, the higher the roughness grade of the cutting surface.