Influence of Geometry and Printing Parameters on the Dimensional and Geometrical Accuracy of 316L Binder Jetting Green Product

Metal Binder Jetting (MBJ) has a great potential for producing complex products in medium to large batches. However, challenges remain in achieving high dimensional and geometrical accuracy. This study investigates the influence of printing parameters and sample geometry on the accuracy of 316L stainless steel green products produced via MBJ. A Design of Experiments (DoE) approach was employed to study four factors at three levels. A Taguchi L9 orthogonal array was designed to evaluate the effects of printhead speed, binder saturation grade, blade speed, and shell thickness on dimensional and geometrical accuracy. Four different geometries were printed and then measured using a coordinate measuring machine (CMM) to assess the accuracy of external and internal dimensions, flatness, and parallelism. The results showed that dimensional accuracy was influenced by printing direction, feature size, and the feature type. External dimensions showed highest accuracy along the powder spreading direction (Y: 0.12% ± 0.21%), followed by building direction (Z: 0.25% ± 0.3%) and binder injection direction (X: 0.40% ± 0.2%). Significantly lower accuracy was found in internal features, showing a negative deviation (X: − 0.66% ± 0.32%; Y: − 0.41% ± 0.23%). Flatness and parallelism errors were found almost constant across experiments, with average values of 0.014 ± 0.008 and 0.024 ± 0.014, respectively. Parallelism appeared to be affected by geometry, specifically, increasing height-to-thickness ratios led to larger errors. Grey relational analysis identified printhead speed as the most critical parameter, followed by binder saturation grade, shell thickness, and blade speed in optimizing the accuracy of the printed parts. ANOVA analysis reveals that printhead has a statistical relevance showing a P-value of 0.029. This work provides novel insights into the printing factors affecting the quality of green parts produced by MBJ. This article helps in identifying the optimal printing parameters for binder jetting of SS 316L.