Graphene-coating on silicon wafer can prevent adhesion between silicon and glass in precision glass compression molding. The main goal of this research is to evaluate the graphene/glass interface friction coefficient, which dictates the flow behavior of glass and the durability of the silicon mold. In this research, barrel compression tests using BK7 glass were conducted at different molding temperatures. The purpose of the tests was to obtain the glass cylinder's axial displacement history and the final dimensions after pressing, both of which were decided by the friction coefficient. First, the friction coefficients were estimated by the empirical equations. Then, finite element analysis was implemented to simulate the friction behavior in the pressing stage. The roles of friction coefficient, molding temperature, and applied force were discussed separately. By comparing the experimental and numerical simulation results, both the axial displacement history plots and friction calibration curves show that the best matching friction coefficient is between 0.20 and 0.25 in the temperature range of 660–700 °C. Furthermore, the specific friction coefficient values in the same temperature range were calculated using linear interpolation of the friction calibration curves, and showed good agreement with the results from the empirical equation. This study also demonstrated that the friction in the graphene/glass interface has no direct correlation with test temperature. In summary, this study revealed graphene coating's extraordinary low and stable friction behavior at high molding temperatures.

The compression molding of precision glass lens is a near net-shape forming process for optical components fabrication. The final profile curve accuracy is one of the most crucial criterions for evaluating the quality of the molded lens. In this research, our purpose was focused on the evaluation of the molded lens curve deviation. By incorporating stress relaxation and structural relaxation model of glass, numerical simulations of the whole molding process for fabricating a planoconvex lens were conducted by utilizing the commercial software msc Marc. The relationship of the three variables, i.e., the lens curve deviation, the mold curve deviation, the gap between the lens and the lower mold, was discussed and the evolution plots with time of the three variables were obtained. Details of the thermal boundary conditions were discussed by considering the contact heat transfer behavior. Then the essentiality of a small gap between the molds and the molded lens after releasing the upper mold was demonstrated. In details, the sensitivity analysis of the processing parameters was conducted, such as the releasing temperature, the cooling rate in the annealing and fast cooling stage, respectively, and the magnitude of the hold-up force. The results showed that the glass lens curve deviation was not sensitive to the choices of the releasing temperature and the cooling rate. What's more, the results indicated that the curve deviation decreased with the hold-up force increasing. Finally, with all the details considered, the final simulation results were presented accurately with good reason.