On the modelling of the specific energy consumption for the continuous fibre fabrication of composite materials

The use of composite materials is growing rapidly, although the manufacturing processes and the produced components require careful consideration from a life-cycle perspective. As a result of recent technological advances, the additive manufacturing (AM) of composites has attracted a great deal of industrial interest, but the environmental impact, compared to more traditional manufacturing routes, has not yet been fully explained. This research has focused on continuous fibre fabrication (CFF), a material extrusion (MEX) process that is capable of producing long-fibre-reinforced components. The energy requirements of CFF have been characterised experimentally by varying the deposition conditions (such as the process parameters, component geometries, reinforcing fibres, and matrix materials). A model, which separately considers the contributions of each deposited material, i.e., the reinforcing fibre or the matrix, to account for the different operating regimes of the system, has been proposed to quantify and estimate the printing energy and the specific energy consumption (SEC). Validation of the model has confirmed a satisfactory predictive capability. SEC values ranging from 17 to 23 kWh/kg (i.e., 161–218 MJ oil-equivalent per kg, where a primary-to-secondary energy conversion efficiency of 0.38 was assumed) have been obtained for fibre-reinforced components. The results suggest that CFF could be energy intensive with respect to high-productivity conventional manufacturing routes, but it could be competitive compared to low-volume processes.