Some common ways to reduce the thermal effects of laser marking machines include:
1, Optimize the focus of the laser beam, can make the energy more concentrated, so that the processed material gasification, rather than produce the phenomenon of ablation. Specifically: first: you can use a shorter focal length of the lens, and second: use a little larger multiplier beam expanding lens to compress the divergence angle.
2, The use of M2 coefficient lower laser, that is, the beam quality is better laser. M2 coefficient is the beam quality factor, we use CO2 RF tube, will find that the imported RF tube marking effect is good, while the domestic RF tube or glass tube marking effect is bad, there will be black or yellow and other phenomena of laser ablation. So we need to try to choose a lower M2 coefficient of the laser, that is, the beam quality is better.
3, The use of shorter wavelength lasers, let's say some people want to mark PP, PE materials, if you use 9.3um laser versus 10.6um laser, you can cut the thermal impact on the surrounding materials and damage, processing results are better.
4, The use of narrower pulse width laser: let's say we use the conventional nanosecond level of 1064nm laser, to process the glass is almost difficult to realize, because the thermal effect is too large, the glass is easy to break or the edge is not smooth. But if we use a picosecond 1064nm laser, you can significantly reduce the thermal effect, combined with the Bessel cutting head, you can cut the glass very well.
5, Reduce the frequency of the PWM signal, reduce the frequency will indirectly raise the peak power of the laser, the peak power is high, this time marking will make the object vaporization, rather than ablation. Of course, this time you need to match the appropriate marking speed.
6, Pre-treatment of materials before marking, such as spraying oxidizers or the use of chemical agents, so that the material surface is easier to laser marking, thereby reducing the thermal effect.
7, Appropriate adjustment of the laser marking machine power and marking speed, reduce the loss of laser on the material, thus reducing the thermal effect.
8, The use of higher-quality field mirrors, galvanometer reflector lenses, combining mirrors, beam expanding mirrors and other optical lenses, so that its laser transmission rate to enhance, thereby reducing the thermal effect of the lens due to the loss of laser light in the optical lens.
9, The use of lens coating must be consistent with the wavelength of the laser, let's say some customers use the laser is 9.3um laser, but they are in the purchase of field lenses, beam expanding mirror, in order to save money, the purchase of an ordinary 10.6um laser with the field lens, beam expanding mirror, but this coating of the lens, the laser's transmittance of 9.3um will be small more than 1%, that is, there is more than 1% of the Energy loss within the lens, these energies will produce thermal effects within the lens, making the lens hot.
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