Rheological design

Using the rheological design, the molds should be dimensioned so that the shear rate in the gate is less than 15,000 1/s, in the sprue less than 5,000 1/s, and in the mold cavity less than 1,000 1/s. In the cavity itself, wall thickness variations, bottlenecks, flow obstructions, sharp corners, the last-filled regions of the mold cavity, and structured surfaces are particularly exposed to wear. 

Studart AR, Zhong W, Pandolfelli VC. Rheological design of zero-cement self-flow castables. Am Ceram Soc Bull 1999 78(5) 65-72. 

O.S. Caneiro, J.M. Nbbrega, F.T. Pinho. Conputer aided rheological design of extrusion dies for profiles. Jomnal of Materials Processing Technology, 2001, 114 75-86. 

For a properly designed and operated cyclone, the sharpness iadex is constant, typically 0.6. The cut size and apparent bypass are a function of the cyclone geometry, the volumetric feed rate, the material relative density, the feed soflds concentration, and the slurry rheology. The relationship for a standard cyclone geometry, where if is the cylinder diameter ia cm and inlet area = 0.05 vortex finder diameter = 0.35 ... 

Compound processibiUty is a key factor in the optimiza tion of new polychloroprene types. As a result, commercial compounds can be mixed, shaped, and cured by virtually all the methods used in the mbber industry. A typical polychloroprene compound includes a variety of additives designed to improve compound rheology, cure rate, and vulcanizate properties. 

For fast-setthug slurries, ensuring conveyance is usually the key design issue while pressure drop is somewhat less important. For nonsettling slurries conveyance is not an issue, because the particles do not separate from the liquid. Here, viscous and rheological behavior, which control pressure drop, take on critical importance. 

Both wet and dry extrusion techniques are available, and both are strongly influenced by the friclional properties of the particulate phase and wall. In the case of wet extrusion, rheological properties of the liquid phase are equally important. See Pietsch [Size Enlargement by Agglomeration, John Wiley Sons Ltd., Chichester, 346 (1992)] and Benbow et al. [Chem. Eng. Sci., 422,2151 (1987)] for a review of design procedures for dry and wet extrusion, respectively. 

Real polymers require more elaborate systems of springs and dash-pots to describe them. This approach of polymer rheology can be developed to provide criteria for design with structural polymers. At present, this is rarely done instead, graphical data (showing the creep extension after time t at stress a and temperature T) are used to provide an estimate of the likely deformation during the life of the structure. 

Design formulas for plastics engineers , Natti S. Rao Hanser Gardner Pubis (1991) ISBN 1569900841. The formulas in this book are classified for specific areas, including rheology, thermodynamic properties, heat transfer, plastic and part type. 

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