Process parameter influence on geometric accuracy of Nylon 12 parts manufactured by FFF

Purpose This study aims to analyze the influence of extrusion temperature, printing speed and layer thickness on dimensional accuracy, geometric deviations and surface roughness of Nylon 12 parts fabricated via fused filament fabrication (FFF). Understanding these effects is key to optimizing the process for precision engineering and biofabrication applications. Design/methodology/approach Hollow cylindrical specimens were printed under varying conditions: extrusion temperature (240°C–270°C), printing speed (40–60 mm/s) and layer thickness (0.1–0.3 mm). Dimensional deviations, roundness, circular runout, cylindricity, straightness and surface roughness were analyzed. Response surface methodology (RSM) was applied to develop predictive models, while gray relational analysis (GRA) was used to optimize process parameters. Findings Higher layer thickness and extrusion temperature increased surface roughness, while higher printing speeds worsened roundness and cylindricity but improved straightness and circular run-out. The optimal parameters identified by GRA were 40 mm/s speed, 0.1 mm layer thickness and 255 °C extrusion temperature. Originality/value This study systematically evaluates geometric deviations in Nylon 12 parts fabricated via FFF, an area with limited prior research. The combined use of RSM and GRA provides a robust approach to minimize geometric errors and enhance print quality, benefiting industries requiring high-precision polymer components, such as aerospace, biomedical engineering and mechanical manufacturing.