Influence of process parameters on the occurrence of defects and dimensional properties of green part produced by material extrusion of highly filled polymer

Material extrusion (MEX) 3D printing of highly filled polymer has demonstrated great capabilities for prototyping or rapid manufacturing of metallic parts exhibiting complex shapes. However, only a few studies have quantitatively examined the dimensional properties of simple shape printed parts and virtually none has investigated the correlation between the printing parameters with their dimensional deviations. Using a high solid loading powder-binder feedstock, a study was conducted on the influence of printing parameters on both the internal defects and dimensional deviations. Microscopic observations were cross-referenced with coordinate measuring machine dimensional measurements to determine the best printing parameters (temperature = 85 degrees C, print speed = 25 mm/s, overlap ratio = 20%, layer height = 0.1 mm) producing no internal voids, while minimizing dimensional deviations in the 75 +/- 15 mu m range. The complex geometry printed using these parameters exhibited dimensional deviations similar to or smaller than those produced by metal injection molding (MIM).