The time- and temperature-dependent constitutive equation of an amorphous polymer was needed for the subsequent finite element analysis so that the residual stress and warpage of a polymer plate, including viscoelastic and phase transformation effects, could be simulated.
Figure 12 compares the predicted warpage using the cooling-plane assumption (uniform temperatures at the part/mold interfaces) to the cooling-channel assumption (uniform temperatures at the cooling channels), with the same temperature differential (60 [degrees] C top, 50 [degrees] C bottom).
Product warpage caused by inappropriate mold design and/or processing conditions is a recurrent problem during the injection molding of thermoplastic materials.
This study also uses the optimal process condition suggested by Taguchi's method as the input layer of the trained BPANN, and compares the shrinkage and warpage predicted by its output layer with the predicted value of Taguchi's method.
The predicted results by the trained base-line network in determining the shrinkage and warpage of training pairs and testing pairs are shown in Fig.
rel] of x-direction shrinkage, y-direction shrinkage and z-direction warpage is 9.
Perhaps of more use to engineers than the accurate prediction of warpage is the ability to discover methods of reducing warpage through changes in processing conditions and part design.
One basic requirement of the research was to mold parts that would easily show warpage while remaining representative of commercial applications.
The third geometry, a channel with a rib on the back edge, and the fourth, a channel with a third wall, both show the effects of structural support on warpage and illustrate the trade-off between stiffness and shrinkage.
A similar approach has been used by Erzurumlu and Ozcelik  to investigate the minimization of the warpage and sink index of molded thermoplastic parts.
Hence, the aim of this study is to investigate the effects of injection-molding parameters during the post-filling stage (packing pressure, packing time, mold temperature, and cooling time) and to determine the optimal selection of parameters for three different types of lignocellulosic polymer composite materials with respect to in-cavity residual stresses, volumetric shrinkage, and warpage properties.
Measurement of In-Cavity Residual Stresses, Volumetric Shrinkage, and Warpage