Process simulation and quality prediction for manufacturing of optical media
Abstract (Summary)A numerical simulation of the injection-compression molding process is developed with the capability of predicting product quality attributes including residual stress, birefringence, and warpage. A hybrid finite element/finite difference method is employed to calculate the temperature and pressure fields of the process with a non-isothermal compressible flow model. The process simulation is coupled with viscoelastic constitutive models to predict the flow and thermally induced residual stresses. A structural finite element analysis is formulated to predict the warpage of the disc due to asymmetric thermal stress and gravity after demolding. The flow and thermally induced birefringence of injection-compression molded optical media is predicted by applying a stress-optical rule to the flow and thermally induced stresses. The resulting model considers the contributions of flow and cooling induced molecular orientation, and the transient effect of thermal stress and pressure on the birefringence. The simulation is validated by compact-disc-recordable moldings with an optical grade polycarbonate under different processing conditions.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/2003