Comparative study of geometric properties of unreinforced PLA and PLA-Graphene composite materials applied to additive manufacturing using FFF technology

In recent years, significant advancements in Fused Filament Fabrication (FFF) have enabled this technology to become one of the most leading techniques of Additive Manufacturing (AM) for the production of functional products. The poor mechanical properties of manufactured parts have traditionally imposed considerable limitations on use of FFF processes. These shortcomings have been overcome using new advanced filaments with nanoparticle reinforced components, short-length and continuous fibres, and other composite material processing technologies. Polymers reinforced with graphene nanoplatelets (GNP) have been an effective solution for improving electrical, thermal, and mechanical properties. However, the geometric properties of functional products manufactured with GNP reinforced polymers have not been analysed in spite of being crucial for the manufacture, assembly, and service life of functional products. The aim of this study was to compare an improved PLA polymer (PLA-3D) with a GNP reinforced PLA composite (PLA-Graphene) by analysing the geometric properties of dimensional accuracy, flatness error, surface texture, and surface roughness. The effect of the 3D printing parameters - build orientation (Bo), layer thickness (Lt), and feed rate (Fr) - on the geometric properties of two PLA-based filaments were evaluated. The results showed dimensional accuracy was mainly affected by the build orientation, where an increase in the layer area on the X-Y plane showing the highest dimensional deviation owing to the longer displacements of the extruder accumulating positioning errors. The dimensional accuracy along the Z-axis was not affected by any of the printing parameters nor the accumulation of layers, with results close to nominal ones. The flatness error and surface roughness were strongly conditioned by building orientation, with the best results obtained in the flat orientation. Neither of the compared materials showed significant variations between them in geometric properties, with similar results in the tested printing conditions.