Multi-objective optimisation in vibration-assisted drilling of CFRP/Al stacks

In this work, carbon fibre reinforced plastic (CFRP) laminate and aluminium (Al7075T6) plates were bonded before undergoing single shot drilling on a vibration platform. The proposed vibration-assisted drilling in the electromechanical-driven system interacting with the cutting condition was shown to achieve outstanding results with regard to material removal, tool wear, hole quality and surface integrity. The statistical significance of individual operating parameters was determined using a main effects plot in conjunction with ANOVA. Multi-objective optimisation in MATLAB coding led to the following optimal combination of operating parameters: cutting speed (148/200 m/min), feed rate (0.08 mm/rev), and vibration frequency (55 Hz) with amplitude (0.005 mm). Surface roughness (CFRP: Ra 0.651 µm, Al: Ra 0.436 µm) was shown to have the least effect on the other seven performance criteria. Equal weighting amongst all objectives was sufficient to improve the overall accuracy (91.96%) in the optimisation. This multi-objective approach largely overcomes the single-objective limitations inherent in the conventional Taguchi method.