Design of a Micro-Hopper Array for Multi-Material Powder Deposition

We present a concept for creating patterned beds of multi-material powder particles using an array of small-scale hoppers. Using this technique, we propose that to place fine particles of multiple fluidized powders discretely in a thin layer as opposed to depositing an entire powder layer of uniform composition using a roller device or doctor blade. Processing and consolidation of multiple, patterned powders can enable fabrication of composite objects with spatially varying structural and multifunctional characteristics. Although theory on the design of small-scale hoppers is lacking, our design for a hopper, its valving, and its particle delivery system are guided by background theory for large hoppers. A hopper array configuration is proposed, and a calculation for deposition time is presented. Delivery of powder was achieved on a prototype hopper. Experimentally measured mass flow rates were used to justify the use of this hopper with SLS and to guide further design improvements.