Thermal Effects of High-frequency Femtosecond Laser Processing of CFRP

Laser selective quantitative removal of CFRP represents a key technology for structural repair in the aerospace industry. However, the huge difference in properties between carbon fiber and epoxy resin in CFRP makes laser processing very challenging, and thermal damage has always been the main obstacle to the widespread application of CFRP laser processing. In order to study the influence of femtosecond laser processing parameters on the machining quality of CFRP, theoretical analysis and experimental verification were carried out by single factor experimental method. The influence of laser energy density, scanning speed and scanning direction on the ablation rate and the width of heat affected zone were analyzed, and the high-precision selective quantitative removal process of femtosecond laser on CFRP was investigated. The results show that when the process parameters are chosen to be θ = 90°, pulse width of 290 fs, power of 7 W, frequency of 100 kHz, scanning speed of 300 mm/s, and scanning spacing of 60～80 µm, the overall ablation surface quality is superior, and the accuracy (roughness) can be as high as 10 µm, and the heat-affected zone (HAZ) on the surface of the removed area is about 33.9 µm.