Analysis of wear of fused silica moulding using glassy carbon moulds

Optical components made of fused silica are in great demand due to the material’s exceptional properties: a broad transmission range from 185 nm to 2.5 μm, low coefficient of thermal expansion, low thermal conductivity and high radiation resistance. For the production of complex optical components in medium and large quantities, the technology of precision glass moulding is particularly suitable. Here, a glass blank is heated up to the moulding temperature and moulded into the desired shape by means of two moulding tools without any subsequent work. The production of the complex moulding tools is still costly in terms of labor and time but the efficiency of the process increases with the number of optical components made by using a pair of moulding tools. Hence, the wear of the moulding tools determines the efficiency of the process. In this paper, an experimental study and FE simulation are presented in order to investigate the wear of the glassy carbon moulding tools in moulding of fused silica. For the FE simulation, the viscoelasticity of fused silica and the friction coefficient between fused silica and glassy carbon were determined. The influence of the process parameters temperature and pressing force on the wear of moulding tools was analysed.