A unified finite element model for the injection molding process

• Published in: Computer methods in applied mechanics and engineering Vol. 178; no. 3; pp. 413 - 429
• Main Authors: Holm, Erik J., Langtangen, Hans Petter
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.1999; Elsevier
• Subjects: Computational methods in fluid dynamics; Exact sciences and technology; Finite element methods; Fluid dynamics; Free boundary problems; Front tracking; Fundamental areas of phenomenology (including applications); Hele–Shaw flow; Injection molding; Non-newtonian fluid flows; Non-Newtonian fluids; Physics; Injection molding; Free boundary problems; Non-Newtonian fluids; Finite element methods; Hele–Shaw flow; Front tracking; Gas liquid interface; Temperature distribution; Computational fluid dynamics; Refinement method; Digital simulation; Free boundary problem; Two dimensional flow; Finite element method; Hele Shaw cell; Mold filling; Polymers; Mesh generation; Heat transfer
• ISSN: 0045-7825; 1879-2138
• DOI: 10.1016/S0045-7825(99)00029-8

The paper presents a simulation model for the injection molding process. A 2D Hele–Shaw approximation is adopted for the polymer flow between two flat plates, whereas the moving polymer–air front is handled by a level-set-like method. The 3D heat equation is solved using finite elements in the flow plane, a spectral method in the perpendicular direction, and finite differences in time. A domain imbedding technique enables simplified treatment of complex mold geometries. Local mesh refinement is applied to improve the numerical accuracy in the vicinity of the polymer–air front. The main advantage of the model is that a common 2D finite element mesh can be used for all the equations. Using object-oriented programming, the compound simulator is efficiently implemented as an assembly of separate simulators for each partial differential equation (PDE) in the model. A case study regarding a simplified model problem, which contains the principal physical effects in the injection molding process, is discussed. We also present simulation results for a more engineering-oriented example concerning the filling of a mold for a computer keyboard.