Compared with traditional oxyacetylene, plasma and other cutting processes, laser cutting has the advantages of fast cutting speed, narrow kerf, small Heat-affected zone, good perpendicularity of kerf edge, smooth kerf, and many kinds of materials that can be cut by laser. Laser cutting technology has been widely applied in fields such as automobiles, machinery, electricity, hardware, and electrical appliances.

Several key technologies of laser cutting machines are integrated technologies of light, machinery, and electricity. The parameters of the laser beam, the performance and accuracy of the machine and CNC system in the laser cutting machine directly affect the efficiency and quality of laser cutting. Cutting accuracy is the first factor in determining the quality of CNC laser cutting machines.

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So, what are the factors that affect the cutting quality of laser cutting machines?

Analysis of factors affecting the cutting quality of laser cutting machines:

The factors that affect the cutting quality of a laser cutting machine include cutting speed, focus position, auxiliary gas, laser output power, and workpiece characteristics. The following will be analyzed in detail.

1. One of the factors affecting the cutting quality of laser cutting machines: laser output power

A laser cutting machine generates energy from a continuous wave output laser beam, and the size and mode selection of the laser power will have an impact on the cutting quality. In practical operation, it is usually adjusted to a higher power to meet the requirements of cutting thicker materials. At this point, the beam mode (the distribution of beam energy in the cross-section) becomes more important. Under conditions of less than high power, a higher power density is obtained at the focal point and better cutting quality is achieved. During the entire effective working life of the laser, the modes are not consistent. The condition of optical components, subtle changes in the gas mixture during laser operation, and flow fluctuations can all affect the mode mechanism.

2. The second factor affecting the cutting quality of laser cutting machines: focus position adjustment

The relative position between the focus and the workpiece surface is particularly important for ensuring cutting quality. In most cases, the focus position during cutting is just on the surface of the workpiece, or slightly below the surface. Ensuring a constant relative position between the focus and the workpiece is an important condition for achieving stable cutting quality throughout the entire cutting process. When the focus is in a better position, the cutting seam is smaller and the efficiency is higher. A better cutting speed can achieve better cutting results. In most applications, the beam focus is adjusted to just below the nozzle. The distance between the nozzle and the surface of the workpiece is generally about 1.5mm.

After focusing the laser beam, the size of the spot is proportional to the focal length of the lens. After focusing the beam through a short focal length lens, the size of the spot is very small, and the power density at the focal point is high, which is beneficial for material cutting; The disadvantage is that the focal depth is very short and the adjustment margin is small, making it more suitable for high-speed cutting of thin materials. Long focal length lenses have a wide focal depth and sufficient power density, making them suitable for cutting thick workpieces.

3. The third factor affecting the cutting quality of laser cutting machines: cutting speed

The cutting speed of the material is directly proportional to the laser power density, that is, increasing the power density can improve the cutting speed. The cutting speed is inversely proportional to the density (specific gravity) and thickness of the material being cut. When other parameters remain unchanged, the factors that increase cutting speed are: increasing power (within a certain range, such as 500-2 000W); Improve the beam mode (such as from high-order mode to low-order mode until TEM00); Reduce the size of the focusing spot (such as using a short focal length lens for focusing); Cutting materials with low initial evaporation energy (such as plastic, organic glass, etc.); Cutting low-density materials (such as white pine); Cut thin materials.

4. The fourth factor affecting the cutting quality of laser cutting machines: auxiliary gas pressure

The use of laser cutting machines for cutting materials requires the use of auxiliary gases, and the magnitude of gas pressure is an extremely important factor. The auxiliary gas is coaxially sprayed with the laser beam to protect the lens from contamination and blow away the slag at the bottom of the cutting area. For non-metallic materials and some metallic materials, use compressed air or inert gas to treat melted and evaporated materials, while suppressing excessive combustion in the cutting area.

For most metal laser cutting, active gas (as long as O2) is used to form oxidation exothermic reaction with hot metal. This additional heat can increase the cutting speed by 1/3~1/2. When high-speed cutting thin materials, high gas pressure is required to prevent slag sticking on the back of the incision (hot slag sticking to the workpiece can also damage the cutting edge). When the material thickness increases or the cutting speed is slow, the gas pressure should be appropriately reduced. In order to prevent the plastic cutting edge from frosting, it is also better to cut at a lower gas pressure.