Exploring the Effects of Processing Parameters on the Flexural Performance of Polylactic Acid Fabricated through a Customized High Extrusion Rate Fused Filament Fabrication System

Fused filament fabrication (FFF) has recently been extended to large-format additive manufacturing (LFAM) systems, which offer substantial advantages for the highly efficient manufacturing of large parts and tools. The aim of this study was to extend the material feeding rate of an open-ended conventional FFF 3D printer, presenting an alternative to the screw extruder-based LFAM systems that are used to date. We investigated the effects of printing parameters, such as nozzle diameter, bead width, and in-plane printing infill direction, on the mechanical performance of processed polylactic acid (PLA) materials. We quantitatively evaluated the mechanical performance of PLA specimens through three-point bending tests. The experimental results demonstrated that the flexural strength and maximum deflection of the FFF specimens are highly sensitive to the parameters of interest, while the flexural stiffness remains stable regardless of variations in parameters. Compared to specimens produced by regular FFF 3D printers, those created using the modified system exhibit 10% increases in bending strength. The extrusion bead width plays a significant role in varying the bending properties of the printed specimens, with maximum differences exceeding 15%. Mesostructural analyses of the interlayer formations of the deposited beads indicated that the layer bead width has a more pronounced effect on the formation of interbead voids than the raster angle, resulting in a more noticeable reduction in mechanical properties.