Study of Nd:YAG laser micro-drilling machinability and parametric optimization of graphite/Epoxy and carbon black/Epoxy nanocomposites

Accurate estimation of the influence of process parameters on the drilled hole quality is imperative for reducing the defects like the taper and the microstructural changes around the holes are frequently encountered during the processing of advanced composite materials involving the laser drilling operations. In this work, the Nd:YAG laser micro-drilling of graphite powder (GP)/Epoxy and carbon black (CB)/Epoxy nanocomposites is performed. The impact of lamp current, cutting speed, assisted air pressure, pulse frequency, and band width on the hole quality attributes, specifically the heat affected zone (HAZ), taper and rate of material removal (RMR) are investigated. The experimentations are planned as per Taguchi's standardized design and contemporary meta-heuristic accelerated particle swarm optimization (APSO) algorithm and the Whale optimization algorithm (WOA) have been utilized to define optimum controllable process parameters. The assortment of the acquired optimum conditions are justified by performing confirmatory tests. GP/Epoxy composites outperform CB/Epoxy composites in terms of hole quality. For single-objective optimization, improvements in taper, HAZ, and RMR for GP/Epoxy and CB/Epoxy nanocomposites are (14.47%, 10.54%, and 16.86%) and (14.64%, 12.72%, and 24.90%), respectively. In multi-performance optimization, WOA exhibits the least error compared to actual values and leads to improved taper (32.64%, 1.29%) and HAZ (10.58%, 10.09%) in GP/Epoxy and CB/Epoxy nanocomposites.