Calculation of the temperature field in injection molding

Abstract

The numerical simulation of nonisothermal effects during the filling stage of injection molding is investigated here. Generalized Newtonian fluid flows are simulated within thin cavities of arbitrary shape. The numerical scheme is based on a hybrid spatial discretization: classical low-order Lagrangian interpolants are used in the midsurface directions, while full polynomials constitute the approximation in the gapwise direction. Discrete equations are obtained by use of the Galerkin finite element method combined with a collocation procedure. Special attention is devoted to the influence of the fountain flow (occurring at the front) on the temperature field. A correct writing of the front thermal boundary condition is derived in agreement with the Hele-Shaw simplified form of the equations. Some illustrative results are presented.

Fiber orientation in simple injection moldings. Part I: Theory and numerical methods

“…For temperature at the flow front we use the treatment of Dupret and Vanderschuren (22). The column of nodes at the flow front translates with the front speed ufront.…”

Elastic flow-front fingering instability in flowing polymer solutions

“…Finally, we wish to mention that most of the numerical modeling studies in injection molding are based on the lubrication approximation to formulate the mold filling problems (see, e.g., Williams and Lord 1975;Hieber and Shen 1980;Dupret and Vanderschuren 1988;Chiang et al 1991;Dupret et al 1999), although a number of recent papers use a fully three-dimensional approach (see, e.g., Pichelin and Coupez 1999;Ilinca and He´tu 2001;Michaeli et al 2001) to address specific problems that need to solve the full Navier-Stokes equations. Nevertheless, all published theoretical studies and simulations are far from predicting flow-front finger-like instabilities described in this study due to the lack of physics in the models used.…”

Isothermal and non‐isothermal crystallization kinetics of polyethylene terephthalate: Mathematical modeling and experimental measurement

“…The structure of spherulites principally consists of chain-folded lamellae radiating from the nucleus as schematically drawn in Rg. 1 and can be regarded as a more or less organized arrangements of crystallites embedded in an amorphous mass. Therefore, a crystallized polymer is in reality semicrystalline, while the maximum degree of crystallinity can reach between 20% and 80%, de-Isothermal and Non-Isothermal C ystallization Kinetics of PET pending on the type of polymer and the crystallization conditions.…”