We determined the best candidate 3D printing material and infill geometry from this analysis, Essentium PLA Gray filament and “grid” infill, respectively, and printed standard surgical Army-Navy retractors to test the mechanical strength of PLA following annealing and autoclaving interventions, both independently and together. Standard and strength-optimized Army-Navy retractor designs created by Chen et al. in Autodesk® Fusion 360™ were used, obtained as STL files (Fig. 2a, b) [27]. The annealing intervention was submersion of the retractors in a 100 °C water-bath for 30 mins, and the autoclaving intervention was autoclaving the retractors for 45 mins at 134 °C and a pressure of 375 PSI.

Specified by Chen et al., the print settings for strength-optimized 3D printed PLA Army-Navy retractors were 30% infill, 3 perimeters, 0.25 in. thickness, 0.75 in. width, “triangles” infill geometry and reinforced joints, which optimizes retractor strength but does not aim to minimize deformation [27].

Standard retractors without intervention failed at 95 N +/− 2.4 N. Hot water-bath annealed retractors failed at 127.3 N +/− 10 N. Autoclave only retractors failed at 15.7 N +/− 1.4 N. Hot water-bath annealed then autoclaved retractors failed at 19.8 N +/− 3.1 N.

Strength-optimized retractors, after the annealing then autoclaving intervention, failed at 164.8N +/− 12.5 N (Fig. 5). For comparison, these retractions fail at 538.5 N +/− 24.9 N without intervention. Retractors displayed mild warping after hot water-bath annealing (Fig. 3).

Chen et al. “Identifying a commercially-available 3D printing process that minimizes model distortion after annealing and autoclaving and the effect of steam sterilization on mechanical  strength.” https://threedmedprint.biomedcentral.com/ Date Accessed: April 25, 2020

This research will definitely assist me with designing future models.