Experimental optimization of support material manufacturing for ULTEM components via FFF

Fused Filament Fabrication (FFF) is a key additive manufacturing method used to produce complex polymer geometries, offering broad design flexibility, efficient material use, and the ability to create intricate features that cannot be achieved through subtractive processes. Among high-performance engineering thermoplastics, polyetherimide-based blends like ULTEM 9085 are widely used in aerospace and automotive industries because of their strong strength-to-weight ratio, thermal stability, and built-in flame resistance. Yet, FFF processing of ULTEM presents demanding manufacturing challenges, especially when structural overhangs call for support structures. Problems such as poor support removal, localized surface damage, dimensional distortion, and deposition irregularities can seriously affect the functional reliability and mechanical properties of the printed parts. This study offers a detailed experimental analysis focused on improving support structure configurations for ULTEM 9085 components using a single-nozzle material extrusion setup. First, a consistent baseline deposition profile covering nozzle motion, volumetric flow rates, and thermal parameters (nozzle, substrate, and build-chamber temperatures) was defined to minimize process-related variation. A fractional factorial Design of Experiments (DOE) approach was then used to assess the main and combined effects of four essential support factors: support pattern, infill density, interface layer presence, and vertical separation distance (Z-gap). The printed samples were examined both quantitatively and qualitatively for visual surface finish, dimensional precision, ease of support removal, mechanical removal behavior, and dimensional consistency. Statistical analysis indicated that support pattern and Z-gap have the strongest influence on surface formation and support detachment. Furthermore, empirical tensile testing combined with macro-mechanical finite element analysis in ANSYS.