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.

Meeting Name

26th Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference, SFF 2015 (2015: Aug. 10-12, Austin, TX)


Mechanical and Aerospace Engineering

Research Center/Lab(s)

Intelligent Systems Center


The authors gratefully acknowledge the financial supports by the National Energy Technology Laboratory of the Department of Energy under the contract DE-FE0012272, and the Intelligent Systems Center at the Missouri University of Science and Technology.

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

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type




Publication Date

12 Aug 2015

Included in

Manufacturing Commons