Investigation of CFRP laser milling using a 30 W Q-switched Yb:YAG fiber laser: Effect of process parameters on removal mechanisms and HAZ formation

A study on laser machining of Carbon Fibre Reinforced Polymer (CFRP) is presented. Experimental tests were carried out on a 4 mm thick CFRP sheet, using a Q-switched 30 W Yb:YAG fiber laser. The aim of the paper is to detect which process parameters and how they affect the laser beam–material interaction, and to explain the effect of the process parameters on the removal mechanisms and HAZ formation. The process parameters examined were: the laser beam scan speed, the pulse frequency, the number of repetitions of the geometric pattern, the distance between two consecutive scan lines and the scanning strategy. The ANalysis Of VAriance (ANOVA) was applied to a two-level factorial design, specifically developed for this aim. Experimental results showed the presence of different interaction mechanisms such as: ablation, matrix burning and mechanical effect. The damage mechanisms and the influence of the process parameters on the HAZ extent are discussed too.