Viscosity Measurement by Cylindrical Compression for Numerical Modeling of Precision Lens Molding Process

Cylindrical compression tests were conducted on two different optical glass grades for determining the high‐temperature viscosity and elastic parameters. Numerical simulations of the compression tests and the precision lens molding process were performed by incorporating the data obtained from the compression tests using a commercial finite‐element method program. Excellent agreement between the viscosity data from the compression test and the beam bending test was obtained, and a good comparison between the measured and predicted deformation load results was also observed. Further issues that have emerged from this research that would be relevant to the ongoing research on the numerical modeling of the precision aspherical lens molding process include determination of high‐temperature elastic properties of glass (i.e. elastic and shear modulus) and friction characterization at the glass–mold interface.