Statistical modelling and optimization of nanosecond Nd:YAG Q-switched laser scarfing of carbon fiber reinforced polymer

This paper explores the effects of laser scarfing on a CFRP tape consisting of unidirectional carbon fiber with a layup of [(45/0/-45/90)4] sym with a total laminate dimension of 5.952 mm. The laser system used in the experimental investigations consisted of a nanosecond Nd: YAG laser source with an average maximum power of 20 W in a pulsed mode. The material was a with a total laminate of 5.952 mm. The laser process aims to investigate the surface modification by laser ablation. In more details, the effects of scanning speed (550 - 650 mm/s) and frequency (23 - 27 kHz) for three different scanning strategies on the scarfing depth, specimen dimensions (in x and y direction) and surface conditions were studied by full factorial experimental plan. By scarfing, the fibers were either oxidized, partially stripped, stripped and excessively stripped. After the statistical analysis, the best results in terms of surface conditions were achieved with the x-parallel laser scanning strategy, where the presence of excessively stripped fibers was not noticed. The mixed-hatching (MH) mode was the strategy that produced the worst results for the scarfing depth, which can negatively affect the ablation rate, even if it turns out to be the most stable strategy. The best results in terms of scarfing depth and x-y dimensions were achieved with MH mode, and with a scanning speed of 600 mm/s and a frequency of 27 kHz.