Characterizing Binder-Powder Interaction in Binder Jetting Additive Manufacturing Via Sessile Drop Goniometry

Understanding the binder-powder interaction and primitive formation is critical to advancing the binder jetting Additive Manufacturing process and improving the accuracy, precision, and mechanical properties of the printed parts. In this work, the authors propose an experimental approach based on sessile drop goniometry on a powder substrate to characterize the binder wetting powder process. As a binder drop penetrates into a prepared powder substrate, the dynamic contact angle formed in powder pores is calculated based on the measured binder penetration time, and the binder penetration depth is measured from the binder-powder granule retrieved from the powder substrate. Coupled with models of capillary flow, the technique provides a fundamental understanding of the binder-powder interaction that determines the material compatibility and printing parameters in binder jetting. Enabled by this gained understanding, it was determined that suspending nanoparticles in a binder could increase the capillary-driven penetration depth, which was then reduced by the further increase of the nanoparticle solid loading and resultant binder viscosity.