Multi-objective Optimization for Porosity and Strength of Selective Laser Sintered Porous Scaffolds Useful in Bone Tissue Engineering

Additively manufactured bone scaffolds have garnered significant attention from researchers in recent years. For successful bone tissue engineering, these scaffolds must demonstrate not only biocompatibility but also an optimal balance of porosity and mechanical strength. This paper explores a multi-objective optimization approach for selective laser sintered polyamide porous bone scaffolds, employing a hybrid Taguchi-based Grey relational analysis method. In this study, five process parameters: layer thickness (LT), build chamber temperature (BCT), build orientation (BO), build position (BP), and powder refresh rate (PRR) were optimized to enhance four response parameters, namely measured porosity (MP), compressive strength (CS), tensile strength (TS), and impact strength (IS) of the porous scaffolds. Experiments were designed using Taguchi's L18 orthogonal array and performed on EOSP395 SLS machine. The signal-to-noise (S/N) ratios were calculated for each experiment, and the Grey relational grades (GRGs) based on these S/N ratios were then computed. The main effect plot of GRG means identified LT1 (120 mu m), BCT2 (175 degrees C), BO1 (0 degrees), BP2 (M), and PRR3 (50%) as the optimal levels for MP, CS, TS, and IS. The analysis of variance of GRGs indicated that LT is the most significant parameter (40%), followed by PRR (33%) and BCT (24%). The result of the confirmation test was compared with the predicted results, revealing deviations of 1.75% for the mean GRG model and 1.64% for the regression model. An absolute improvement of 28% was observed in process performance by comparing GRGs at initial and optimal levels of the parameters.