A Pneumatic Conveying Powder Delivery System For Continuously Heterogeneous
Material Deposition In Solid Freeform Fabrication
by
Shawn Fitzgerald
Jan Helge Bøhn, Chairman
Mechanical Engineering, Virginia Polytechnic Institute and State University
Abstract:
Great improvements are continuously being made in the solid freeform
fabrication (SFF) industry in terms of processes and materials. Fully
functional parts are being created directly with little, if any, finishing.
Parts are being directly fabricated with engineering materials such as ceramics
and metals. This thesis aims to facilitate a substantial advance in rapid
prototyping capabilities, namely that of fabricating parts with continuously
heterogeneous material compositions. Because SFF is an additive building
process, building parts layer-by-layer or even point-by-point, adjusting
material composition throughout the entire part, in all three dimensions, is
feasible. The use of fine powders as its build material provides the potential
for the Selective Laser Sintering (SLS), Three-Dimensional Printing (3DP), and
Freeform Powder Molding (FPM) processes to be altered to create continuously
heterogeneous material composition. The current roller distribution system
needs to be replaced with a new means of delivering the powder that facilitates
selective heterogeneous material compositions. This thesis explores a
dense-phase pneumatic conveying system that has the potential to deliver the
powder in a controlled manner and allow for adjustment of material composition
throughout the layer.