Evaluation of Mechanical, Thermal, Rheological, and Biocompatibility Properties of Additively Manufactured Metal‐Reinforced Biocomposites Optimized by Reinforcement Ratios and Printing Parameters

ABSTRACT Polylactic acid (PLA) is a biodegradable thermoplastic widely used in biomedical devices; however, its inherent brittleness and poor impact resistance restrict its use in mechanically demanding environments. This study investigates the mechanical, thermal, microstructural, and in vitro cytocompatibility performance of fused deposition modeling (FDM)‐printed PLA/316L stainless steel (SS) biocomposites (3–15 wt%). Composite filaments were produced by melt compounding and printed using a Taguchi‐based experimental design to assess the combined effects of reinforcement content and key FDM parameters, including raster orientation, nozzle temperature, and printing speed. Mechanical performance was evaluated through tensile, compressive, and Charpy impact testing, supported by microstructural and thermal characterization. A multi‐response Taguchi–Gray Relational Analysis (GRA) was employed to identify optimal processing conditions. Under optimal conditions (15 wt% SS, 0° raster), tensile and compressive strengths reached 94 MPa and 102 MPa, respectively, alongside a significant improvement in impact energy absorption. Thermal analyses confirmed stability within the FDM processing window, while microstructural observations revealed a transition from homogeneous particle dispersion to agglomeration‐driven defects at higher SS contents. Indirect cytotoxicity assessment following ISO 10993‐5 guidelines using L929 fibroblasts demonstrated no acute cytotoxic response for any composite formulation after 72 h of extract exposure. Overall, the findings demonstrate that SS reinforcement, combined with controlled FDM parameters, yields PLA composites with substantially improved mechanical properties while maintaining short‐term cytocompatibility, thereby supporting patient‐specific, non‐load‐bearing biomedical applications.