Influence of Raster Orientation and Feeding Rate on the Mechanical Properties of Short Carbon Fiber-Reinforced Polyamide Printed by Fused-Filament Fabrication

Fused-filament fabrication (FFF) is an extremely popular additive manufacturing process due to its affordability, relative ease to operate, and wide range of possible materials. It is also notorious for the hundreds of different process variables, which often are overlooked in favor of parameters considered to be more relevant for mechanical performance, such as printing and bed temperatures, printing speed, and layer height. Thus, this study is aimed at evaluating some of the less frequently studied process variables, namely raster orientation angles (and their stacking sequence) and feeding rate. Based on this, the influence of these variables on the tensile and flexural properties of short carbon fiber-reinforced polyamide printed by FFF was assessed. The study concluded that stacking layers with raster angles of 0°/90° and +30°/-30° resulted in the best trade-off between tensile and bending properties, with the former reaching ultimate tensile and flexural strengths of 111 ± 1 and 137 ± 5 MPa, respectively. The study also found that there was no increase in part density or mechanical properties when the volumetric flow was increased up to 120% of the intended road volume. Therefore, the hypothesis that an increase in flow rate would result in less inter-road gaps could not be confirmed with the current setup.