Optimization of Printing Parameters Using Taguchi Method to Improve the Quality of Parts Produced by Metal Binder Jetting

This work aims at improving the quality, meaning both dimensional accuracy and green density, of binder jetting products by the optimization of printing parameters. Cubes with a squared through hole were printed using AISI 316L stainless steel powder, varying four printing parameters: dark body (binder saturation), shell thickness, printhead, and powder spreading speed. Taguchi methodology was employed to design nine orthogonal experiments, permutating the four factors at three levels. The green density was measured by mass to volume ratio, and the dimensions of the printed parts were derived by coordinate measuring machine (CMM) measurements. Green density and dimensional accuracy were the response variables to be optimized. It was observed that green density varied in the interval (0.53 ÷ 0.57) of relative density; ANOVA (ANalysis Of VAriance) showed that the highest contribution to maximize green density (81%) is given by dark body. Concerning dimensional accuracy, the difference between measured and nominal dimensions, referred to nominal dimensions, varied between 0.53% and −1.01%. Dimensions parallel to binder injection direction (X) are mostly affected by shell thickness and dark body (35% and 55%, respectively). Printhead speed and powder application speed, instead, mostly affect dimensions parallel to powder spreading direction (Y) and dimensions aligned with building direction (Z)—printhead speed 56% for Y and 37% for Z, powder application speed 30% for Y and 24% for Z, respectively. A physical explanation is discussed, moreover linear regression models are proposed for optimizing parameters.