Optimization of Dimensional Accuracy and Surface Roughness of Fused Filament Fabrication Printed Hip Implants

Rapid investment casting is a casting process in which the sacrificial patterns are fabricated using additive manufacturing techniques. The surface quality and accuracy of the rapid investment cast geometries are dependent on the surface roughness and dimensional characteristics of the printed patterns. This study aims to investigate the effect of printing parameters on the dimensional accuracy and surface roughness of fused filament fabrication printed patterns. A small-scale prosthetic biomedical implant for total hip replacement was selected as a benchmark model due to its practical significance. Taguchi’s design of experiments was used with an L18 orthogonal array as an optimization technique. ANOVA, and the interaction plots were applied to analyze the effects of the process parameters on the printed patterns. The main results indicate that the most significant printing parameter affecting surface roughness is build angle, followed by layer thickness. The optimum parameters that minimize the surface roughness are 0.1 mm layer thickness, 0 build angle, 100% infill density, nozzle temperature of 21 °C, and extrusion speed of 40 mm/s. As for dimensional accuracy, the optimum printing parameters are 0.1 mm layer thickness, 0 build angle, 50% infill density, nozzle temperature of $200^{\circ}\mathrm{C}$, and extrusion speed of 50 mm/s.