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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.

Since governments encourage sustainability, industries are making great efforts to reuse or recycle carbon fibre–reinforced polymer (CFRP) composites. Despite the promising early results concerning the material properties of recycled CFRP, there is no published knowledge available about their machinability. In this study, drilling-induced micro and macro-sized geometrical defects were analysed and compared in virgin and recycled CFRP. A total of 180 drilling experiments were carried out using uncoated solid carbide cutting tools. Six different CFRP composites were tested at different feeds. The burr characteristics and microstructure were analysed by optical and scanning electron microscopy. The analysis of variance (ANOVA) results suggest that the formation of drilling-induced burrs in CFRP reinforced by recycled chopped and nonwoven mats is less pronounced than in virgin CFRP. Micro- and macro-sized geometrical defects in both recycled and virgin milled CFRP were negligible. This study found no relevant objection to using recycled CFRP from the point of view of drilling-induced burrs and microstructure damage.

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