Additive manufacturing of high density carbon fibre reinforced polymer composites

Additive manufacturing (AM) of carbon fibre reinforced thermoplastic composites can offer advantages over traditional carbon fibre manufacturing through improved design freedom and reduction in production time and cost. However, the carbon fibre composites produced using current state-of-the-art AM approaches generally possess high porosity (18–25 %) compared to those produced by conventional manufacturing (1 %). An approach known as composite fibre additive manufacturing (CFAM) is presented, involving selectively printing a binder and polymer powder onto discontinuous carbon fibre sheets, which are then compressed, heated and post-processed to form net shape components. The results demonstrate a correlation between compaction pressure applied and porosity/fibre volume fraction within components. Composite components were produced containing porosity of 1.5 % and fibre volume content of 15 % with 97 MPa tensile strength and 8.9 GPa elastic modulus, presenting a new approach for production of discontinuous carbon fibre reinforced polymer parts with mechanical properties exceeding those of state-of-the-art AM.