In this work, two mathematical models for the simulation of the injection molding process were tested and their predictions were validated with experimental data. One of these models is based on the well-known "Hele-Shaw" approximation which, is commonly used by a considerable number of commercial packages. This method utilizes the fact that generally the flow is confined in a narrow gap in which out-of-plane flows may be ignored and, therefore, only a two-dimensional (2-D) solution of the flow field is necessary. One remarkable limitation of this approach is its impossibility of predicting the so-called "fountain flow". Furthermore, this model neglects the role of crystallization kinetics. On the other hand, the other model proposes a methodology that deals with fountain flow and crystallization. It is based on the so-called "2½-D" numerical simulation since it combines a 2-D flow analysis with a 3-D solution of the energy equation. First, a two-dimensional analysis in the gap-wise direction is performed in order to obtain fountain flow information. Then, in-plane two-dimensional flow solutions are coupled with three-dimensional energy results, which incorporate the heat generated by crystallization. Two different thermoplastics were investigated. Polyethylene was selected to characterize the crystalline behavior. Polystyrene was chosen as the amorphous material. In order to obtain insight of the overall injection molding cycle, pressure evolution in the cavity and in the nozzle was examined carefully. More accurate pressure results were computed when using the 2½-D model. This study thus puts in evidence the importance of including fountain flow and crystallization kinetics in the injection molding process.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.30248 |
| Date | January 2000 |
| Creators | Hernández Aguilar, José Ramón. |
| Contributors | Kamal, Musa R. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001746525, proquestno: MQ64224, Theses scanned by UMI/ProQuest. |
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