Multi response optimization for compressive strength, porosity and dimensional accuracy of binder jetting 3D printed ceramic bone scaffolds

Additively manufactured bone scaffolds have been gaining attention of researchers for past couple of years. Besides biocompatibility, bone scaffolds are expected to exhibit a good combination of porosity, mechanical strength and dimensional accuracy for success of the bone tissue engineering. This paper presents a multi objective optimization for additively manufactured ceramic porous bone scaffold prototypes using hybrid Taguchi based Grey relational analysis approach. Five process parameters namely, layer thickness (LT), build orientation (BO), build position (BP), binder saturation (BS) and delay time (DT) of binder jetting 3D printing process have been optimized for three response parameters, namely compressive strength (CS), measured porosity (MP) and dimensional accuracy (DA) of fabricated porous scaffolds. Initially, experiments are designed and performed as per the Taguchi's L27 orthogonal array and signal-to-noise (S/N) ratios for all the experiments have been calculated. Then Grey relational grades (GRGs) of S/N ratios are computed. Main effect plots for means and S/N ratios of GRGs reveals LT1, BO1, BP2, DT1 and BS2 as optimum levels of process parameters for CS, MP and DA. Analysis of variance of GRGs suggests that BO (40.42%) the most, LT (29.81%) the second most and DT (5.19%) the least significant parameter in affecting the response parameters. The value of GRG at optimum levels of the parameters have been predicted using the mean GRG model and liner regression model. Finally, a confirmation test is performed and result has been compared with the predicted values. A deviation of 3.93% (mean GRG model) and 3.89% (regression model) have been observed between experimental and predicted values of GRGs.