Binder Injection Additive Manufacturing

This paper introduces binder injection additive manufacturing (AM), an emerging technology combining the advantages of material extrusion and binder jetting. Binder injection AM is demonstrated to be a versatile and capable manufacturing process. This paper details the basic theory underpinning binder injection AM, equipment modifications, nozzle-powder interactions, and process parameter investigations. A diverse array of powders and binders, including glass/PVA, cement/sodium silicate, sand/PVA, sawdust/pine resin, sawdust/epoxy, polystyrene/ABS slurry and sugar/sugar syrup were evaluated, with preliminary results indicating significant potential for the binder injection method in handling an expansive spectrum of powdered materials, especially low-cost and recycled powders. Print tests showcased the capability of this method to produce complex geometries quickly and accurately. The study presents the relationship between binder injection rates and printed track dimensions. Intersecting tool paths are explored and are found to be possible with this method. Post-processing methods for enhancing part strength are presented.  Finally, recommendations for future work are provided.