Currently, there is no industrial sorting process for separating fibre-containing material from waste streams. The aim of this study is therefore to identify carbon fibre reinforced plastic (CFRP) in different waste streams using an inductive heating method. For this purpose, a conveyor belt transports different material fractions under a coil, whereby the material is heated by induction, and reaches into the visual field of a thermal camera, whereby the heating behaviour of the different materials is determined and compared.
The visual effects of different material combinations at different conveyor belt speeds, different height distances between the inductor coil and the specimen, and different specimen sizes are investigated. The material fractions investigated include various semi-finished CF products such as scrims, fabrics and nonwovens, as well as their combination with a plastic matrix (CFRP with multiaxial fabric, unidirectional (UD)-reinforced CFRP, and a nonwoven made of recycled CF and thermoplastic matrix). The research scope of the study also includes the investigation of different material combinations of CFRP, glass fibre reinforced plastic (GFRP), CFRP-aluminium hybrids, steel and wood.
The results show that CFRP structures heat up by induction. However, the heating behaviour is strongly dependent on the material and structure of the test specimen examined. A differentiation between CFRP and materials not containing CFRP is unproblematically possible in all cases. This means that materials containing CFRP can potentially be sorted out from waste streams (both production and End-of-Life waste) coming from industries like aviation, wind or automotive, through the newly developed sorting process by means of inductive heating and thus fed into a high-quality recycling path.