Effect of Printing Parameters on Mechanical Strength and Surface Roughness of Material Extrusion-Printed PLA Fabricated Using a Customized 3D Printer

Material Extrusion (MEX) has emerged as one of the most prevalent techniques in additive manufacturing; however, the mechanical performance and surface quality of the fabricated components are strongly influenced by the selected processing parameters. This study systematically investigates the effect of nozzle temperature, layer height, infill density, printing speed, wall thickness and raster angle on the tensile strength and surface roughness of polylactic acid (PLA) partsfabricated using a custom-built single-extruder 3D printer. A full factorial design with two levels and two replications was implemented, and analysis of variance (ANOVA) was applied to identify statisticallysignificant effects. Results revealed that layer height and raster angle are the dominant factors affecting surface roughness, while infill density, layer height, and nozzle temperature most strongly determine tensile strength. Best combination was achieved with a nozzle temperature of 220 °C, layer height of 0.1 mm, infill density of 100%, printing speed of 70 mm/s, wall thickness of 1.2 mm, and raster angle of 0°. The proposed process improves both durability and surface quality, which in turn enhances reliability and broadens the applicability of PLA components in industrial manufacturing as well as in cost-effective rapid prototyping.