This study investigates the influence of selective laser sintering (SLS) process parameters, laser power, scan spacing, and build orientation on the mechanical behavior of polymer parts manufactured from polyamide (PA12), glass-filled polyamide (PA12-GF), and polypropylene (PP). The purpose of this paper is to evaluate how these parameters affect tensile properties, including strength and elongation, as well as flexural stress under bending conditions. To address this objective, tensile specimens were designed according to ASTM D638 standards, while modified geometries were used for three-point bending tests. Samples were fabricated using controlled variations in laser power and scan spacing at two build orientations (0° and 90°). Mechanical characterization was performed through tensile and three-point bending tests to obtain stress–strain and flexural stress–strain behavior for each material and processing condition. The results show that laser power and scan spacing jointly control energy density, significantly affecting part densification, porosity, tensile strength, elongation, and flexural stress. Higher laser power combined with appropriate scan spacing improved particle fusion, resulting in increased strength and flexural performance, while excessive energy input led to thermal defects and reduced performance. Build orientation also had a significant impact, with 0° specimens exhibiting higher tensile strength, elongation, and flexural stress compared to 90° specimens due to stronger in-plane bonding relative to interlayer adhesion. Based on these findings, it is concluded that the mechanical performance of SLS-produced parts is governed by the combined effects of process parameters and anisotropic behavior, requiring careful optimization to achieve reliable and high-quality components. It is recommended that future work expand the range of process parameters, improve control of powder reuse, include additional mechanical and microstructural characterization, and investigate a broader range of materials and processing methods for comparison.
