Shape transferability and microscopic deformation of molding dies in aspherical glass lens molding press

Glass molding press (GMP) experiments have been performed to fabricate aspherical glass lenses. Shape transferability of the GMP process was evaluated by examining the form accuracy and surface roughness of the molding dies and the molded lenses. Nanometric surface roughness and submicron level form accuracy have been confirmed on the resulting lenses. It was also found that the molding dies underwent microscopic deformation and topographical change, and the durability of the molding die was strongly dependent on their curvature radii. To clarify this effect, finite element analysis of glass deformation in the GMP process was conducted, and a strong location-dependence of material flow and stress/strain distribution in the molded lens were observed. Based on the simulation results and the experimental data, possible approaches to improve the service life of the molding dies were discussed.