Electrical properties of 3D printed continuous carbon fibre composites made using the FDM process

Abstract

Fused deposition modelling (FDM) is an additive manufacturing process for the 3D printing of continuous fibre-thermoplastic composite laminates. The electrical conductivity of continuous carbon fibre (CF)-nylon filaments and laminates printed with a Markforged MarkTwo® FDM machine is experimentally investigated. The axial electrical conductivity of single filaments measured before, during and following the FDM process reveal a large reduction (∼40%) due mostly to breakage of carbon fibres. The electrical conductivity of 3D printed laminates made by the layer-by-layer deposition of the single filaments were determined in the longitudinal, transverse and through-thickness directions, and compared to the electrical properties of a hot moulded composite with a near-equivalent carbon fibre content. The longitudinal conductivity of the 3D printed laminate was only ∼50% that of the hot moulded composite, and this was due mostly to fibre breakages caused by the FDM process. However, the transverse and through-thickness electrical conductivities of the 3D printed laminate were higher (∼13 times and ∼3 times, respectively) than the hot moulded composite due to higher fibre waviness causing increased fibre-to-fibre contact which aids the flow of electrical current in these two directions.