Influence of Particle Size Distribution in Metal Binder Jetting - Effects on the Properties of Green and Sintered Parts

In binder jetting, parts are build layer-by-layer in a powder bed by locally printing an organic binder. After curing the binder, the green parts are cleaned of the loose powder. A combined furnace process removes the binder and fuses the particles together. The microstructure of a sintered part depends on powder properties, green part density and sintering parameters. The influence of the particle size distribution (PSD) on the sintering behaviour is widely known. With decreasing particle size, the sintering activity increases. This enables a reduction of the sintering temperature and reduces the distortion potential. Finer powders have higher capillary forces and tend to agglomerate, which affects packing density and flowability. This paper takes a closer look at the influence of PSD and layer thickness on density and dimensional accuracy of the green parts. The effects on shrinkage behaviour and sintering density of binder-jetted parts are also shown.