On Porosity and Flexural Strength of FDM Parts Printed using Short Carbon Fiber Reinforced Polyamide 6 Filament

Fused deposition modeling (FDM) has several advantages, including design freedom, part customization, and ease of realizing complex geometries. However, there exist some challenges with the process; these include but are not limited to porosity, anisotropy, roughness, and material compatibility. This study is focussed on the additive manufacturing of polymer composites (short carbon fiber reinforced polyamide 6) through the process of FDM. Such 3D-printed parts are very lightweight and possess superior mechanical properties, which makes them a potential candidate for applications where a high strength-to-weight ratio is desired. The combination of FDM parameters, namely nozzle temperature, layer height, and flow rate, are studied in this work. The effect of variation in these parameters on the porosity and flexural strength is recorded following the Taguchi design of experiments. In calculating porosity, the weight difference between the printed part and the CAD part is used. For the flexural test, the standard three-point bending test is performed. The optimal combination of parametric settings is observed to be the same for minimum porosity and maximum flexural strength. Moreover, the flow rate is identified as a significant parameter for FDM printing of the composite material under study. The prints obtained at a raster angle 0˚/90˚ and on-edge orientation are observed to have better flexural strength than the prints at a raster angle ±45˚ and flat orientation.