Tailin Fan

Three-Dimensional Printing: The Physics and Implications of Additive Manufacturing

Abstract Three Dimensional Printing is a process for creating parts directly from a computer model. 3D Printing builds parts in layers by spreading a layer of powder and then selectively joining the powder in the layer by ink-jet printing of a binder material. After all layers are printed, the layer loose of powder is removed to reveal the finished part. Application areas include ceramic molds for metal castings, directly printed parts for end-use and for use as tooling, ceramic preforms for metal matrix composites, structural ceramic parts, and others. 3D Printing is a member of a group of layer manufacturing techniques which have the primary distinguishing feature of creating parts by the controlled addition (rather than subtraction) of material. The primitive building element in 3D Printing is a spherical ensemble of powder particles held together by one droplet of binder. Ballistic effects are important in the formation of primitives due to kinetic energy associated with the incoming droplet. Stitching together of droplets forms surfaces and hence determines surface finish. Vertical dimensional control is determined in pan by the compression of powder layers by subsequently applied powder. These physical mechanisms help to determine the dimensional control and surface finish of 3D Printed parts.

Three Dimensional Printing: Surface Finish and Microstructure of Rapid Prototyped Components

Three Dimensional Printing is a process for rapid prototyping of functional components. Thin layers of powder are bound in selected areas by ink-jet printing of a liquid binder. Layers are added sequentially until a three dimensional part is completed. The unbound powder is then removed. The raster scan pattern and layering used in forming has an observable effect on the surface finish and microstructure of the part, as does the chemistry of the particular materials system used. Important phenomena include ballistic interaction of the jet with the powder bed and wicking of the binder. Process parameters such as layer height, flow rate, and powder density were studied. Microstructural examination of the printed components is also reported.