Fabrication of highly dense parts with complex geometry by paste-extrusion-based solid freeform fabrication processes requires a precise control of the extrusion flow rate to dispense material on demand, which is often referred as Extrusion-On-Demand (EOD). The extrusion process for aqueous ceramic pastes is complex and difficult to control due to their non-Newtonian behavior, compressibility and inhomogeneity. In this study, three methods of EOD (based on ram extruder, needle valve, and auger valve) are introduced and investigated for the extrusion of high solids loading (i.e., > 50%, volumetric) aqueous alumina paste. Optimal extrusion process parameters for these methods are determined through printing tests and analysis. The extrusion performance in terms of extrusion start and stop accuracy, as well as flow rate consistency, is compared and analyzed for the three methods. Advantages and disadvantages of these three methods are also discussed.
W. Li et al., "Methods of Extrusion on Demand for High Solids Loading Ceramic Paste in Freeform Extrusion Fabrication," Proceedings of the 26th Annual International Solid Freeform Fabrication Symposium (2015, Austin, TX), pp. 332-345, University of Texas at Austin, Aug 2015.
26th Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference, SFF 2015 (2015: Aug. 10-12, Austin, TX)
Mechanical and Aerospace Engineering
Intelligent Systems Center
Keywords and Phrases
Additives; Alumina; Aluminum oxide; Fabrication; Non Newtonian flow; Process control, Complex geometries; Extrusion process; Freeform fabrication; High solids loadings; Non-Newtonian behaviors; Paste extrusions; Precise control; Tests and analysis, Extrusion
Article - Conference proceedings
12 Aug 2015