Experimental study of the maximum resolution and packing density achievable in sintered and non-sintered binder-jet 3d printed steel microchannels

Developing high-resolution 3D printed metallic microchannels is a challenge especially when there is an essential need for high packing density of the primary metal. While high packing density could be achieved by heating the structure to the sintering temperature, some heat sensitive applications require other strategies to improve the packing density of primary metal. In this study the goal is to develop microchannels with high green (bound) or pack densities on the scale of 100-300 microns which have a robust mechanical structure. Binder-jet 3D printing is an additive manufacturing process in which droplets of binder are deposited via inkjet into a bed of powder. By repeatedly spreading thin layers of powder and depositing binder into the appropriate 2D profiles, complex 3D objects can be created one layer at time. Microchannels with features on the order of 500 microns were fabricated via binder jetting of steel powder and then sintered and/or infiltrated with a secondary material. The droplet volume of the inkjetdeposited binder was varied along with the print orientation. The resolution of the process, the subsequent features sizes of the microchannels, and the overall microchannel quality were studied as a function of droplet volume, orientation, and infiltration level.