Density variation in binder jetting 3D-printed and sintered Ti-6Al-4V

Abstract

Binder jet printing is one additive manufacturing technique utilized in today’s industry that uses an adhesive to bind powders together selectively in a bed. Post-printing processes are necessary for binder jet printed parts to increase key properties in materials such as density, but the full effects of this post-processing are not yet well understood. This study aims to enhance the understanding of how the process of sintering can affect the density evolution of a Ti-6Al-4 V binder jet printed part. Results show that the density is lower at the edges of the part and higher in regions of significant topological curvature, likely due to variations originating from the printing process that are propagated. These printing process effects can be due to binder- or powder-related occurrences, which are described in relation to the obtained results. Binder effects include high-velocity impact, particle disruption, and excessive spreading. Powder effects include printhead and recoater speed, satellite particles, and changing pressure throughout the powder bed. These factors affected the coordination number of particles in the green part, and caused sintering to progress more slowly in certain areas.