A Novel Assessment of the Thermo-Mechanical Behavior of Chemically Bonded 3D-Printed Sand Cores

Thermal and mechanical stability of sand cores is crucial for the success of castings, as the cores must resist the thermo-mechanical load of molten metal until its solidification, while maintaining the required dimensional and geometrical accuracy. Although sand 3D printing with binder jetting technology is a highly effective method for manufacturing sand cores, there is still no clear understanding in the literature of how printing configurations affect the thermo-mechanical behavior of the cores. To this aim, this work investigates the printing homogeneity of an industrial binder jetting machine under different configurations (part orientation and position in the building box) using data obtained from hot distortion test (HDT). From HDT curves, important curve features were extracted and analyzed; some of them showed statistical correlations, indicating that a single feature is not sufficient for comparing HDT curves. The analysis revealed a sensible difference in the thermo-mechanical behavior of the 3D-printed cores with the printing directions. In particular, the cores printed along the build direction exhibited both a statistical reduction of the breakage time and an increase of maximum deflection. Conversely, the HDT response of the cores across the different locations inside the printer building box revealed a much less significant difference. This method supports the optimization of the 3D printing process design, toward the improvement of the printability of highly complex core geometries.