Surface effects in powder based rapid prototyping

Abstract

An increasing number of emerging Rapid Prototyping and Manufacturing (RP&M) processes are powder-based. In recent years these processes have shifted from producing form parts from polymer powders to producing structural parts using metal and ceramic powders. The use of metal and ceramic powders increases the utility of these processes to industry. One of the problems associated with these RP&M processes, especially the powder based ones, is obtaining the required surface quality. A review of two powder-based processes with a special emphasis on surface quality is provided. This includes an analysis of the surface and core material of a part manufactured by the Freeform Powder Molding (FPM) rapid prototyping process as well as a part manufactured using a molded binder assisted feedstock method. An optical microscopy and SEM analysis of the parts manufactured with the FPM process as well as the parts molded with the binder assisted feedstock illustrates the capabilities and limitations of each approach. Density gradients, typically between the surface and core of the material are related to the powder characteristics as well as to the component shape definition techniques. Possible methods of improving the current surface quality of the FPM parts are also discussed.