Working Principle of Laser Cutting
Laser cutting is equipped with a laser generator that emits a high-energy laser beam. The laser beam will then be focused by a lens and form a very tiny high-energy spot. By focusing the light spot at the appropriate position, the material will absorb the energy of the laser and then evaporate, melt, ablate or reach the ignition point. Then the high-pressure auxiliary air (CO2, oxygen, nitrogen) blows away the waste slag. The laser head is driven by a program-controlled servo motor and moves along a predetermined route on the material to cut out workpieces of different shapes.
Categories of Laser Generators (Laser Sources)
Light can be divided into red light, orange light, yellow light, green light, etc. It can be absorbed or reflected by objects. Lasers are also very light. And lasers of different wavelengths have different characteristics. The gain medium of the laser generator is the medium that converts electricity into laser, which determines the wavelength, output power and application of the laser. The gain medium can be gaseous, liquid and solid.
1. The most typical gas laser is CO2 laser;
2. The most typical solid-state lasers include fiber lasers, YAG lasers, laser diodes, and ruby lasers;
3. Liquid lasers use liquids such as organic solvents as working media to generate lasers.
Different materials absorb lasers of different wavelengths. Therefore, the laser generator must be carefully selected. For the automotive industry, the most commonly used laser is the fiber laser.
Working mode of laser source
Laser sources usually have 3 working modes: continuous mode, modulation mode, and pulse mode.
In continuous mode, the output power of the laser is constant. This makes the heat entering the material more uniform, so it is suitable for high-speed cutting. This not only improves work efficiency, but also worsens the effect of the heat-affected zone.
In modulation mode, the output power of the laser is equal to the function of the cutting speed. It can keep the heat entering the material at a relatively low level by limiting the power at each point to avoid uneven cutting edges. Because its control is a bit complicated, the working efficiency is not high and it can only be used for a short time.
Pulse mode can be divided into ordinary pulse mode, super pulse mode, and super strong pulse mode. But their main difference is only the difference in intensity. Users can make a decision based on the characteristics of the material and the accuracy of the structure.
In summary, lasers usually work in continuous mode. But in order to obtain optimized cutting quality, for some materials, the feed speed needs to be adjusted, such as acceleration, deceleration and delay during turning. Therefore, in continuous mode, it is not enough to simply reduce the power. The laser power must be adjusted by changing the pulse.
Parameter setting laser cutting
According to different product requirements, it is necessary to constantly adjust the parameters under different working conditions to obtain the best parameters. The nominal positioning accuracy of laser cutting can reach 0.08mm, and the repeat positioning accuracy can reach 0.03mm. But in actual conditions, the minimum tolerance is ±0.05mm for the aperture and ±0.2mm for the hole position.
Different materials and different thicknesses require different melting energies. Therefore, the output power required by the laser is different. In production, factory owners need to strike a balance between production speed and quality, and choose the appropriate output power and cutting speed. Therefore, the cutting area can have appropriate energy and the material can be melted very effectively.