Fused filament fabrication (FFF) is one of the widely utilized kinds of 3D printers in various industrial, medical, and scientific applications. This is due to the low cost of the printer, ease of use, and the variety of inexpensive filaments they offer compared to other 3D printers. Polylactic acid (PLA) filament has become one of the most popular filaments in FFF 3D printers due to its low cost, simplicity of printing, environmental friendliness, and biodegradability. Small processing window, low mechanical properties, and poor thermal resistance have limited its use. To address this, PLA composites are used to improve their properties. On the other hand, process parameters affect the properties and quality of FFF 3D printed composite parts, and optimization of these parameters is important. Hence, this chapter investigated and optimized the effects of process parameters on the mechanical properties of FFF 3D printed samples. Pure PLA and PLA/Aluminum composites were the filaments utilized. Printing speed and raster angle were chosen as process input parameters. The experiments were designed using the Taguchi method, and statistical optimization was done using signal-to-noise ratio (SNR) analysis. The results demonstrated that the maximum tensile strength for PLA/Al composite samples is obtained at the printing speed of 20mm/s and a raster angle of -45/45°, while the maximum elongation-at-break is obtained at the printing speed of 20mm/s and a raster angle of -30/60°. Additionally, the examination of the SNR showed that the elongation-at- break was most affected by printing speed, while the tensile strength was most affected by the type of filament.
