RT Journal Article T1 Process parameter influence on geometric accuracy of Nylon 12 parts manufactured by FFF. A1 Martín-Béjar, Sergio A1 Bañón-García, Fermín A1 López Fernández, José Andrés A1 Bermudo-Gamboa, Carolina K1 Impresión 3D K1 Nailon - Fabricación AB PurposeThis 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/approachHollow 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.FindingsHigher 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/valueThis 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. PB Emerald YR 2025 FD 2025-11-04 LK https://hdl.handle.net/10630/46375 UL https://hdl.handle.net/10630/46375 LA eng NO Martín-Béjar S, Bañón García F, López-Fernández JAA, Bermudo Gamboa C (2026), "Process parameter influence on geometric accuracy of Nylon 12 parts manufactured by FFF". Rapid Prototyping Journal, Vol. 32 No. 1 pp. 123–141, doi: https://doi.org/10.1108/RPJ-03-2025-0101 NO https://openpolicyfinder.jisc.ac.uk/publication/2982?from=single_hit DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 5 may 2026