ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 41, (2) 47 - 54 (1997)


STEPS TOWARDS RATIONAL MODELLING OF CERAMIC INJECTION MOLDING
 
Pabst Willi, Havrda Jiří, Gregorová Eva
 
Department of Glass and Ceramics, Institute of Chemical Technology Prague, Technická 5, 166 28 Prague

An attempt is made to set up the fundamentals for applying mathematical process modelling on the basis of rational thermomechanics to the forming process of oxide ceramic pastes plasticized by thermoplastic binders. Using a continuum description throughout we start with the local balance equations known from traditional continuum mechanics and mention the special status of the entropy inequality. Looking for a material model as simple as possible but as complex as needed, constitutive theory is used to deduce a simple fluid model (the generalized Newtonian liquid) with the help of constitutive principles, and for the one-dimensional case the Herschel-Bulkley model is suggested. In order to make the theory liable to experimental verification, idealizations are made concerning flow geometry. Boundary conditions are shortly discussed. Apart from delivering a rational framework for the modelling of ceramic injection molding, the methodological approach applied in this paper should be of value also for other widely used forming processes in ceramic technology, especially cold extrusion, extrusion at elevated temperature or hot extrusion.


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