Characterization and effects of process parameters on the mechanical, microstructural, and thermal behavior of PEEK in fused deposited modeling 3D printing

Polyether ether ketone (PEEK) is a high-performance thermoplastic polymer known for its exceptional mechanical strength, high thermal stability, and chemical resistance, making it suitable for aerospace, automotive, and biomedical applications. The aim of this study is to characterize and analyze the effects of process parameters on 3D Printed PEEK, using numerical modeling and experimental investigation. Finite element analysis (FEA) using ANSYS Workbench was applied to investigate molten PEEK flow through the nozzle and assess the influence of critical process parameters including printing temperature (380°C, 400°C, and 420°C), nozzle diameter (Ø0.4 mm), layer thicknesses (0.2 mm, 0.25 mm, and 0.3 mm), and filament feeding speeds (20 mm/s, 25 mm/s, and 30 mm/s). The simulation considered relevant boundary conditions and thermal-fluid material properties to replicate realistic flow behavior. The results demonstrated that nozzle diameter significantly affected pressure drop, while printing temperature and feeding speed influenced viscosity and temperature distribution within the nozzle. A smaller nozzle diameter increased pressure drop, while higher temperatures and feeding speeds improved molten PEEK flow behavior, positively impacting the quality of printed parts. Phase transformations during extrusion were also observed, from solid to vitreous and then to liquid as the temperature increased. These transitions were found to influence the bonding quality and uniformity of extruded layers. Experimental validation was performed on 3D-printed PEEK samples using the same set of process parameters. The simulation modeling was employed to select critical printing parameters and understand the flow behavior of PEEK prior to actual FDM printing. Mechanical testing showed that impact strength improved with increasing printing temperature, ranging from 44 KJ/m 2 at 380 °C to 50 KJ/m 2 at 420 °C, while achieving a UTS of 120 MPa and modulus of 4.6 GPa. Interaction effects indicated that lower printing speeds (20 mm/s) enhanced interlayer adhesion through prolonged thermal contact, especially with moderate layer thicknesses of 0.2–0.25 mm. Unlike previous studies, this work also investigated multiple properties, Mechanical properties, physical properties, including porosity and density, alongside thermal stability, crystallinity, and microstructure. The results demonstrate that careful optimization of printing parameters significantly improves the overall performance of 3D-printed PEEK. These findings provide comprehensive guidance for producing high-quality, mechanically robust PEEK components.