Study on HAZ extension characteristics during laser ablation of CFRP based on dimensional analysis

Heat affected zone (HAZ) is one of the key factors in evaluating quality in laser processing of carbon fiber reinforced polymer (CFRP). To achieve a systematic and quantitative description of continuous wave (CW) and pulsed wave (PW) laser ablation of CFRP, dimensional analysis was applied to establish the HAZ extension models. The HAZ morphology and fracture microstructure were characterized, and the characteristics of the ablation plume and gas diffusion were observed. The HAZ extension models show good prediction effect on HAZ and the key dimensionless numbers that determine the HAZ are found. Relating the dimensionless numbers to the HAZ extension characteristics provides a quantitative optimization direction for avoiding excessive ablation. Differences in the heat accumulation process of CW laser and PW laser ablation are concluded, which lead to complex comprehensive effect among the parameters. The resulting differences in the effects of CW and PW laser parameters on the HAZ are comparatively studied. PW laser ablation under the parameters of high repetitive frequency and low scanning speed is found to exhibit the properties of CW laser in the HAZ extension characteristics including size and morphology.