Machining holes in CFRP with laser “drilling + boring” hybrid technique

This paper presents a novel approach for machining carbon fiber reinforced polymer composite (CFRP), wherein a laser "drilling + boring" hybrid technique is employed. The method consists of initial high-energy pulsed laser drilling at high speeds, followed by subsequent low-energy short-pulsed laser trimming of the hole edges. A detailed examination was carried out on machining accuracy, taper angle, surface roughness, the heat affected zone (HAZ), microstructure, and mechanical properties of the CFRP samples machined with this technique. The findings revealed that the circular holes exhibit a machining accuracy of approximately 30 μm, accompanied by a taper angle measuring 0.37°. Moreover, the regions surrounding the holes display a smooth and pristine surface, devoid of burrs, fiber fractures and serrated textures. Notably, compared with laser rotary cutting method, the "drilling + boring" hybrid technique demonstrates enhancements in surface finish, HAZ control, and mechanical property of the machined holes.