3-D finite element model for gas-assisted injection molding Simulations and experiments
article
Although gas-assisted injection molding (GAIM) has been practiced in industry for more than a decade, the process is not completely understood, particularly with respect to the gas penetration mechanism. Consequently, mold design and process control are often governed by trial-and-error, and reliable information on the gas distribution and the final product properties can often only be obtained from experiments. To gain a better understanding of the gas-assisted injection molding process, we have developed a computational model for the GAIM process. This model has been set up to deal with (non-isothermal) three-dimensional flow, in order to correctly predict the gas distribution in GAIM products. It employs a pseudo-concentration method, in which the governing equations are solved on a fixed grid that covers the entire mold. Both the air downstream of the polymer front and the gas are represented by a fictitious fluid that does not contribute to the pressure drop in the mold. The model has been validated against both isothermal and non-isothermal gas injection experiments. In contrast to other models that have been reported in the literature, our model yields the gas penetration from the actual process physics (not from a presupposed gas distribution). Consequently, it is able to deal with the 3-D character of the process, as well as with primary (end of gas filling) and secondary (end of packing) gas penetration, including temperature effects and generalized Newtonian viscosity behavior.
Topics
TNO Identifier
953563
ISSN
00323888
Source
Polymer Engineering and Science, 41(3), pp. 449-465.
Publisher
Wiley
Pages
449-465
Files
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