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Prediction of process‐induced warpage in injection molded thermoplastics
Author(s) -
Akay M.,
Ozden S.,
Tansey Tony
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10579
Subject(s) - materials science , mold , composite material , deflection (physics) , molding (decorative) , heat deflection temperature , residual stress , curing (chemistry) , finite element method , thermal , transfer molding , temperature gradient , core (optical fiber) , structural engineering , izod impact strength test , ultimate tensile strength , physics , quantum mechanics , meteorology , optics , engineering
The main cause of warpage in injection moldings is the imbalance of the thermal residual stresses that are caused by a non‐uniform temperature distribution through the thickness of the moldings resulting from variation in cross sections, part geometries, and temperature difference between the mold surfaces. As the hot plastic melt is injected into the relatively cooler mold, a temperature gradient develops between the core of the molding and its surfaces, determining the magnitude of the residual stresses and warpage deflection. The relationship between the temperature difference of the two halves of the mold and warpage for a flat plate was measured and predicted by use of a finite element software package. The development of warpage in a 3D component (L‐shaped bracket) was also measured, and the results were compared with computer predictions.