The effects of material extrusion (MEX) process parameters on dimensional aspects of polycaprolactone for coronary stent applications

Ensuring dimensional accuracy in material extrusion (MEX) polycaprolactone (PCL) stents is critical for clinical performance, yet published studies report inconsistent parameter effects. This work systematically evaluated four MEX process parameters—extrusion temperature (TE), material deposition speed (vD), extrusion multiplier (ME) and layer thickness (tL)—on strut width (wS), stent thickness (tS) and stent length (lS) across three representative geometries (Hybrid A, Hybrid C, Chevron B). Twenty-one parameter combinations were experimentally tested, with dimensional data measured by optical microscopy and subsequently analysed using ANOVA and response-surface modelling (RSM) to quantify main effects, interactions and optimise outcomes. Results showed that ME and TE dominated wS and lS deviations, tL most strongly influenced tS, while vD had only minor, geometry-dependent effects. Complex geometries with acute angles (Chevron B) amplified interaction effects and trade-offs between dimensions. RSM multi-factor optimisation combined with experiments identified compromise windows balancing wS, tS and lS (TE: 150–180 °C, vD: 30–50 mm/s, ME: 130–140%, tL: 0.2 mm). Stent geometry critically governs parameter sensitivity, indicating that robust MEX-based fabrication of PCL stents requires geometry-aware optimisation rather than universal approach.