PRELIMINARY INVESTIGATIONS ON THE DEPOSITION OF FINE POWDERS THROUGH MINIATURE HOPPER-NOZZLES APPLIED TO MULTI-MATERIAL SOLID FREEFORM FABRICATION

摘要

A concept for multi-material solid freeform fabrication is proposed to enable the fabrication of heterogeneous components. This concept features nozzles designed for depositing thin layers of multiple patterned materials followed by selective laser sintering for consolidation to desired densities. Although prior work on the design of small-scale nozzles for powder delivery is lacking, our design is guided by background theory for particle flow through hoppers. Experimental guidelines for the delivery of powders with particle sizes in the 10-125μm range through hopper-nozzle orifices with diameters in the 0.5-2mm range are presented. This is a preliminary investigation of particle flow behavior necessary for continuous mass flow rates under gravity, low gas pressure-assisted flow, and vibration-assisted flow conditions. As proof of concept, several patterned beds of single and multiple materials were deposited on an X-Y table. A simple model to predict the linewidth of lines deposited by gravity flow is presented.