Reducing the taper and the heat-affected zone of CFRP plate by Micro fluid assisted laser induced plasma micro-drilling

Abstract

Carbon Fiber Reinforced Plastics (CFRP) with superior mechanical properties are widely used in aerospace, automotive, and medical fields. The characteristics of CFRP with anisotropy and inhomogeneous result in poor machining performances by conventional drilling techniques. Laser drilling is a non-contact high precision machining technique without tool wear but leads to a large heat-affected zone (HAZ) and taper. Although underwater laser drilling could reduce thermal damage on CFRP surface, bubbles produced in the machining process severely affect the machining stability and surface quality. In this study, a micro fluid-assisted laser-induced plasma drilling (MFA-LIPMD) method was proposed to relieve the negative effect of bubbles as well as reduce the taper and HAZ. A comprehensive analysis of hole surface quality, HAZ, taper, and mechanical properties was conducted, and MFA-LIPMD performed more advantages over laser in the air (LIA) and laser-induced plasma drilling (LIPMD). It was found that the taper of micro-holes was reduced by 42.8%–51.78%, and the thermal damage rate of micro holes processed by the MFA-LIPMD process was reduced by 65.3%–68.1% compared with the LIPMD process, and the maximum tensile load of samples was increased by about 7.68%. Therefore, MFA-LIPMD has great potential for machining high-quality micro holes of CFRP plates.