Optimizing FDM Printing Parameters to Reduce Deformation in Annealed HTPLA Patient-Specific Instruments

Computer-Aided Design (CAD) and Additive Manufacturing (AM), particularly Fused Deposition Modelling (FDM) with PLA, are increasingly used in medicine for cost-effective production of sterilizable patient-specific instruments (PSIs). This study investigates which printing parameters most influence deformation after annealing, a key pre-sterilization step, to identify optimal 3D printing settings that minimize geometric distortion. Experiments were conducted using 24 factorial design to evaluate the effects of raft thickness, infill orientation, first-layer pattern, and cooling fan speed on three-dimensional deformation and deformation on plane A, parallel to the printing plane, and plane B, longitudinal to the specimen, then projected in a 23 design with replicates. Lower fan speed (25%) and a 45° infill orientation minimized overall deformation, while a 90° orientation reduced distortion on Plane A. Results varied across planes, likely due to the anisotropic nature of FDM parts. Despite limitations, this study provides a first insight into deformation behavior in larger PSIs and supports future optimization efforts.