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Molded geometry and viscoelastic behavior of film insert molded parts
Author(s) -
Kim Seong Yun,
Kim Sung Ho,
Oh Hwa Jin,
Lee Seung Hwan,
Baek Soo Jin,
Youn Jae Ryoun,
Lee Sung Hee,
Kim SunWoo
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.29121
Subject(s) - materials science , composite material , shrinkage , ultimate tensile strength , viscoelasticity , annealing (glass) , residual stress , finite element method , creep , deformation (meteorology) , stress relaxation , thermal , structural engineering , physics , meteorology , engineering
Virgin injection‐molded tensile specimens without any inserted film and four kinds of film insert molded (FIM) tensile specimens were prepared. They were annealed at 80°C to investigate the effect of residual stresses and thermal shrinkage of the inserted film on thermal deformation of tensile specimens. The FIM specimens with the unannealed film were bent after ejection in such a way that the film side was protruded and the warpage was reversed gradually during annealing and the film side was intruded. Warpage of the FIM specimen with the film annealed at 80°C for 20 days was not reversed during annealing. Processing of the FIM specimens have been modeled numerically to predict thermoviscoelastic deformation of the part and to understand the warpage reversal phenomenon (WRP). Nonisothermal three‐dimensional flow analysis was carried out for filling, packing, and cooling stages. The flow analysis results were transported to a finite element stress analysis program for prediction of deformation of the FIM part. The WRP was caused by the combined effect of thermal shrinkage of the inserted film and relaxation of residual stresses in the FIM specimen during annealing. It is expected that this study will contribute towards the improvement of the FIM product quality and prevention of large viscoelastic deformation of the molded part. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009