Multi-response optimisation of machining parameters during candlestick drilling composite material using membership function and Taguchi method

In this study, the effectiveness of the proposed approach is demonstrated through combined both membership function (MF) and Taguchi method to optimise the machining parameters with multiple performance characteristics in drilling carbon fibre–reinforced plastic (CFRP) by the candlestick drill bits. The MF with multiple performance characteristics (delamination factor and surface roughness) indicate that the feed rate and the spindle speed are the most important factors in drilling CFRP laminates. Confirmation results show that the optimal process parameters in drilling the CFRP laminates can be determined effectively, the delamination factor is decreased from 1.152 to 1.137 (mm/mm), and the surface roughness is decreased from 0.75 to 0.52 (Ra), respectively, leading to a multiple performance characteristics in drilling qualities through combined both MF and Taguchi method.