A design framework for multi-thermal optimization of ULTEM 1010 using open-source FDM: unlocking its additive manufacturing potential

• Developed a thermal design optimization framework of ULTEM 1010 for open-source FDM. • Independently optimized printing, DAS, and post-process heat treatment temperatures. • Improved UCSs by about 3.7% and interlayer adhesion through multi-thermal tuning. • Outperformed or matched industrial FDM in strength across all building orientations. • Demonstrated a low-cost, scalable method for high-performance polymer printing. Polyetherimide (ULTEM 1010) is a high-performance thermoplastic polymer widely used in aerospace, transportation, and biomedical engineering due to its excellent thermal and mechanical properties. However, its integration into fused deposition modeling (FDM) remains challenging due to poor interlayer adhesion, anisotropy, and thermal processing constraints. This study presents a multi-thermal process design framework to enhance the mechanical performance of ULTEM 1010 parts fabricated using an open-source FDM platform equipped with a direct annealing system (DAS). By systematically optimizing three thermal parameters, printing temperature, DAS temperature, and post-process heat treatment, we achieved significant improvements in interlayer bonding, porosity control and mechanical performance. The optimized parts (375 °C printing, 300 °C DAS, 225 °C heat treatment) demonstrated mechanical properties comparable to or exceeding those fabricated on industrial systems. Compression and tensile testing across multiple build orientations, supported by fractographic analysis, confirmed enhanced intralayer and interlayer fusion and reduced air gap content. These findings establish key structure–property-process relationships and demonstrate that thermally tuned open-source systems can deliver engineering-grade part quality. The proposed framework provides a scalable and cost-effective strategy for tailoring interlayer architecture in the additive manufacturing of high-performance polymers.