Title

Freeform Extrusion of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling

Abstract

A novel, solid freeform fabrication method has been developed for the manufacture of ceramic-based components in an environmentally friendly fashion. The method is based on the extrusion of ceramic slurries using water as the binding media. Aluminum oxide (Al2O3) is currently being used as the part material and solids loading as high as 60 vol. % has been achieved. This paper describes a novel manufacturing machine that has been developed for the extrusion of high solids loading ceramic slurries. A critical component of the machine is the deposition system, which consists of a syringe, a plunger, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and curve fitting techniques are utilized to construct the dynamic model. The results demonstrate that the ceramic extrusion process has a very slow dynamic response, as compared to other non-compressible fluids such as water. A substantial amount of variation exists in the ceramic extrusion process, most notably in the transient dynamics, and a constant ram velocity may either produce a relatively constant steadystate extrusion force or it may cause the extrusion force to steadily increase until the ram motor skips. The ceramic extrusion process is also subjected to significant disturbances such as air bubble release, which causes a dramatic decrease in the extrusion force, and nozzle clogging, which causes the extrusion force to slowly increase until the clog is released or the ram motor skips.

Department(s)

Mechanical and Aerospace Engineering

Second Department

Materials Science and Engineering

Sponsor(s)

Air Force Research Laboratory (Wright-Patterson Air Force Base, Ohio). Materials and Manufacturing Directorate
Air Force Research Laboratory (Wright-Patterson Air Force Base, Ohio)
United States. Air Force

Keywords and Phrases

Ceramic; Extrusion; Freeform

Library of Congress Subject Headings

Slurry

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2006 University of Texas Press, All rights reserved.


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