A drilling case study in polymer composites reinforced by virgin and recycled carbon fibres (CFRP and rCFRP) to analyse thrust force and torque

A great deal of attention is currently paid to recycling or reusing carbon fibres, as it improves sustainability and the lifetime of carbon products. The applicability of recycled carbon fibre–reinforced polymer (rCFRP) composite materials is supported by the results of material scientists; however, the machinability of rCFRPs has not been analysed yet. The machinability of virgin and rCFRPs was compared by analysing cutting force and torque in drilling. Six different CFRPs (virgin and recycled CFRPs with different reinforcing structures) were drilled at three feed levels using two different solid carbide cutting tools. The cutting force and torque were measured with a KISTLER 9257BA dynamometer, processed, and analysed by fast Fourier transformation (FFT) and analysis of variance (ANOVA). The experimental results proved at a significance level of 0.05 that the recycled/virgin status of the applied CFRPs significantly influences both the thrust force and drilling torque of each CFRP. Furthermore, the cutting force and torque are higher in rCFRPs than in virgin CFRPs at each reinforcing structure. The present study suggests spreading rCFRP applications, as there are no essential barriers against them from the point of view of drilling force and torque.