The development of freeze-form extrusion fabrication (FEF) process to fabricate three-dimensional (3D) ceramic parts with use of sacrificial material to build support sections during the fabrication process is presented in this paper. FEF is an environmentally friendly, additive manufacturing (AM) process that builds 3D parts in a freezing environment layer-by-layer by computer controlled extrusion and deposition of aqueous colloidal pastes based on computer-aided design (CAD) models. Methyl cellulose was identified as the support material, and alumina was used as the main material in this study. After characterizing the dynamics of extruding alumina and methyl cellulose pastes, a general tracking controller (GTC) was developed and applied to control the extrusion force in depositing both alumina and methyl cellulose pastes. The controller was able to reduce the time constant of the closed-loop system by more than 65% in comparison to the open-loop control system. Freeze-drying was used to remove the water content after the part has been built. The support material was then removed in the binder burnout process. Finally, sintering was done to densify the ceramic part. The fabrication of a cube-shaped part with a square hole in each side that requires depositing the sacrificial material during the FEF process was demonstrated.
Development of Freeze-Form Extrusion Fabrication With Use of Sacrificial Material
Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received April 15, 2014; final manuscript received September 4, 2014; published online October 24, 2014. Assoc. Editor: Darrell Wallace.
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Leu, M. C., and Garcia, D. A. (October 24, 2014). "Development of Freeze-Form Extrusion Fabrication With Use of Sacrificial Material." ASME. J. Manuf. Sci. Eng. December 2014; 136(6): 061014. https://doi.org/10.1115/1.4028542
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