Research Papers

Extrusion Process Modeling for Aqueous-Based Ceramic Pastes—Part 1: Constitutive Model

[+] Author and Article Information
Mingyang Li

e-mail: ml89c@mst.edu

Lie Tang

e-mail: lietangmst@gmail.com

Robert G. Landers

e-mail: landersr@mst.edu

Ming C. Leu

e-mail: mleu@mst.edu
Department of Mechanical and
Aerospace Engineering,
Missouri University of Science and Technology,
Rolla, MO 65409

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received February 9, 2013; final manuscript received June 25, 2013; published online September 11, 2013. Assoc. Editor: Donggang Yao.

J. Manuf. Sci. Eng 135(5), 051008 (Sep 11, 2013) (7 pages) Paper No: MANU-13-1056; doi: 10.1115/1.4025014 History: Received February 09, 2013; Revised June 25, 2013

The extrusion process for aqueous-based ceramic pastes is complex due to the non-Newtonian behavior of these pastes. In this study, the extrusion process is modeled by characterizing the ceramic paste viscosity using a modified Herschel–Bulkley model. The steady-state relationship between plunger velocity and extrusion force is built based on this viscosity model and the Navier–Stokes equations. The influence of air, which may be trapped in the paste during the paste preparation and loading processes, is also examined as it significantly affects the dynamic response of the extrusion force. Combining these effects with the steady-state extrusion model, a constitutive law for the extrusion process of aqueous-based ceramic pastes is created. Because of the compressibility introduced by the trapped air, the dynamic response of the extrusion force is described by a first-order nonlinear equation when plunger velocity is taken as an input. It is shown that the extrusion response time depends on the amount of air in the extruder and the magnitude of the extrusion force. Air bubble release, a phenomenon that causes the extrusion force to suddenly drop due to the change of paste volume in the nozzle, is analyzed based on the developed constitutive model.

Copyright © 2013 by ASME
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Grahic Jump Location
Fig. 1

Schematic of a volume of compressible air in an incompressible paste flowing in a pipe

Grahic Jump Location
Fig. 2

Schematic of a layer of compressible material above incompressible paste

Grahic Jump Location
Fig. 3

Air bubble release schematic representation




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