Optimization of FDM process parameters for achieving fluid-tight TPU elastomers in pressurized oil environments

Abstract

Achieving reliable fluid-tight sealing in pressurized fluid environments remains a significant challenge in Fused Deposition Modeling (FDM) due to layer-by-layer micro-porosity (the “FDM Factor”). This study establishes a systematic framework for optimizing the process parameters of Thermoplastic Polyurethane (TPU 95A) to maximize the structural and hermetic integrity of printed parts. Utilizing a 2 5–1 Fractional Factorial Design, we investigate the influence of nozzle temperature, print speed, layer height, infill density, and infill pattern on surface roughness (R a ), Shore hardness, and 20% compressive strength. Statistical analysis via ANOVA identifies “Interaction Dominance,” revealing that the Speed × Infill ( p = 0.005) and Temperature × Infill ( p = 0.015) interactions are more critical determinants of compressive performance than individual variables in isolation. A specialized slicing strategy employing high wall loops and randomized seam positions was validated to eliminate vertical “zipper effect” leak paths. While hydrostatic validation on dynamic and static geometries (U-cups and oil seals) demonstrates functional fluid-tight performance up to 50 bars, the long-term viscoelastic limitations, creep, and fatigue wear of printed TPU relative to conventional vulcanized Nitrile Rubber (NBR) are systematically discussed to define practical industrial boundaries. The findings provide a mathematically grounded framework for the digital warehousing of functional elastomeric components.