Drilling of recycled carbon fibre-reinforced polymer (rCFRP) composites: analysis of burrs and microstructure

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.