High-power continuous wave (CW) infrared (IR) lasers (kilowatt power level) can process carbon fiber reinforced composite materials at higher speeds, but leave an unacceptably large amount of heat-affected zone on the material. On the other hand, ultrafast laser pointer can bring a low heat-affected zone, but usually the processing speed of the material will be relatively slow.
Therefore, the challenge is to find a laser source and process that can achieve a good balance of speed and quality. Pulsed nanosecond lasers have good processing speed and quality, and the wavelength often has a significant impact on the final result. In particular, strong absorption at ultraviolet (UV) wavelengths enables high-quality processing.
Spectra-Physics’ high-power UV laser and TimeShift pulse shaping technology are very suitable for the ablation, cutting and drilling of carbon fiber reinforced composite materials without damaging the fibers, while achieving high speed and quality.
In order to demonstrate the capabilities of UV lasers, we processed a carbon fiber reinforced composite sheet based on polyacrylonitrile (PAN) with a thickness of 250μm. We used different pulse widths, powers, repetition rates, and scan speeds. We also tested the performance of pulse train processing performed by the technology. We compared the cutting speed and heat-affected zone (in this case, the average length of the fiber exposed along the cutting path) in various situations.
The results show that this green laser pointer can achieve good processing speed and quality. Using 2ns pulse can get the smallest heat-affected zone ~15μm. This is an average value obtained under multiple processing conditions, and in some cases the heat-affected zone is actually zero. Pulse train processing is very advantageous, it can increase the cutting speed by 20-50% under the same average power. Through additional process development and optimization, this laser can now cut 250μm thick carbon fiber reinforced composite sheets at a speed of 70mm/s, while the heat-affected zone is less than 15μm.