Investigation of hole morphology in 3D printed CFRP composites during femtosecond laser micro-drilling process

Producing micro holes in 3D printed continuous carbon fiber reinforced polyamide (CFRP) composite is crucial for reducing turbulence, decreasing fuel consumption, and improving the formability of composite panels. However, the anisotropic characteristics of CFRP composites provide significant challenges in the manufacturing of accurate micro-holes. This study employs a novel hybrid scanning technique to create micro holes in 3D printed CFRP composites utilizing femtosecond laser technology. The results show that while using laser power density of 458 kW/cm2, pulse repetition rate of 20 kHz, and scanning speed of 450 mm/s, the hybrid scanning approach substantially improves circularity and reduces taper angle. Furthermore, compared to circular and double ring approaches, the time needed to make holes is lowered by 44% and 12%, respectively. The selection of laser parameters and scanning methods has a direct impact on the development of thermal damage flaws on the hole wall surface. Circular and double-ring scanning methods have imperfections such as striations, fiber damage, uneven surfaces, recast layers, and fragments on the hole wall surface, however hybrid scanning methods are flawless.