Some common methods for reducing the thermal effects of laser marking machines include:
1. Optimizing laser beam focus
Optimizing the focus of the laser beam can make the energy more concentrated, causing the material to vaporize rather than burn.
Specifically, this can be achieved by using lenses with shorter focal lengths and larger expanding mirrors to compress the divergence angle.
2. Use of lasers with lower M2 values
2. Use of lasers with lower values of M2, which refers to the beam quality factor. When using a CO2 RF tube, it may be found that imported tubes have better marking effects than domestic ones, which tends to result in darkening or yellowing due to laser erosion.
Therefore, lasers with lower M2 values should be selected to obtain better beam quality.
3. Using lasers with shorter wavelengths
Using lasers with shorter wavelengths can reduce thermal impact and damage to surrounding materials when marking materials such as PP and PE.
For example, using a 9.3um laser instead of a 10.6um laser can produce better processing effects.
4. Using lasers with narrower pulse widths
Using lasers with narrower pulse widths can also reduce thermal effects. For example, using a conventional 1064nm nanosecond laser it is almost impossible to process glass due to the large thermal effect, causing the glass to crack or have jagged edges.
However, using a 1064nm picosecond laser can significantly reduce the thermal effect, combined with the Bessel cutting head, it can cut glass very well.
5. Reducing the frequency of the PWM signal
Reducing the frequency of the PWM signal can indirectly increase the peak power of the laser, which can cause the material to vaporize instead of burning. Naturally, this requires matching an appropriate dialing speed.
6. Material pre-processing before marking
Pre-processing the material before marking, such as spraying oxidant or using chemicals, can make it easier to mark the surface of the material with the laser, thereby reducing thermal effects.
7. Adjusting the marking power and speed of the laser marking machine
Properly adjusting the power and marking speed of the laser marking machine can reduce the loss of laser energy in the material, thereby reducing thermal effects.
8. Using high-quality optical lenses
The use of high-quality optical lenses such as field mirrors, vibrating mirror reflection mirror lenses, collimating lenses and expansion lenses can increase their transparency to the laser, thereby reducing thermal effects caused by energy loss due to to laser damage to optical lenses.
9. The lens coating must match the wavelength of the laser.
For example, some customers use a 9.3um laser, but buy ordinary 10.6um lenses to save costs. This type of coating reduces the transmission rate of the lens by more than 1% for a 9.3um laser, meaning that more than 1% of the energy is lost in the lens, producing thermal effects.
