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Optimization of compression molding of stand-alone microlenses: Simulation and experimental results



Hot compression molding is a promising method to fabricate polymer stand-alone microlenses. A reliable theoretical as well as statistical analysis is required for the optimization of the process to minimize the residual stresses and to predict the amount of springback to achieve a better replication of the mold profile. This article in this context focuses on the finite element simulation (FES), optimization as well as experimental validation of hot compression molding of polymer stand-alone microlenses. Three steps such as molding, cooling, and demolding, under different molding parameters, were analyzed using ABAQUS/standard solver and the results were compared with experimental results. Compression test and compression relaxation test have been conducted at different temperatures and strain rates to characterize the rheological behavior of material. Two material models, linear viscoelastic and hyperelastic–viscoelastic models, were developed and used for compression test simulations. Hyperelastic–viscoelastic model is found to predict the material behavior in low strain rates better and, thus, is used for the simulation of actual lens compression molding. Good agreement is found between the FES-predicted curve and the lens profile molded at different molding temperatures. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers