Optimisation of the Friability Property of Sand Moulds Produced by the Binder Jetting Process

Unlike traditional sand moulding techniques, the binder jetting process is based on layer-by-layer manufacturing, which significantly influences the cohesion of sand grains and the final friability of the sand moulds. The latter property is critical as it is responsible for the presence of sand inclusions in the final casting and thus the mechanical properties. The friability property of 3D printing has not been systematically investigated and reported upon in metal casting and foundry literature. This study assesses the friability of three-dimensional AFS sand test specimens produced using the binder jetting process. In addition, the study attempts to model and optimise the friability property using the central composite design, a response surface methodology in Design-Expert,^® to optimise two critical parameters of the binder jetting printer including the grain size and printhead speed to minimise the friability property of sand moulds. The experiment revealed that the quadratic and cubic models of optimisation are the best fit for the correlation. The lowest values of the friability were achieved when the AFS value is closer to 55 in the quadratic model and between 57 and 55 AFS in the cubic model while the ideal value of the printhead speed is above 0.29 mm/s for both models.