Development and experimental evaluation of a research-oriented precision glass molding apparatus for micro-optical structure replication

Precision glass molding (PGM) is a near-net-shape process for fabricating high-precision glass optical components, whose replication accuracy depends on coupled thermal, force, displacement, and pressure-holding conditions. To support process-parameter optimization and micro-optical structure replication, an open-architecture, research-oriented molding apparatus was designed, constructed, and evaluated. The compact system integrates short-wave infrared heating, independently regulated upper and lower thermal zones, vacuum/nitrogen atmosphere control, water-cooled seal protection, and force/displacement feedback. Thermal stability tests showed that under a 600 °C holding condition, the deviations of the upper and lower mold-base temperatures from the set temperature eventually converged to within 7 °C, while the two mold bases temperature difference was reduced to within ±1 °C during the stable stage. Both mold bases were maintained above 700 °C for more than 600 s in the ultimate heating test. Mechanically, the apparatus separates chamber actuation from molding loading. A 400 mm electric vertical linear guide opens, closes, and seals the vacuum heating chamber, whereas the lower loading shaft provides a 48 mm loading travel. Micro-displacement control tests showed a minimum return positioning error of 1.226 μm over a 200 μm total travel. Force feedback is provided by an external 5 kN pressure sensor with 0.05% full-scale accuracy, while the actual force-tracking behavior was shown to depend on target force and pressure-holding regulation speed rather than on a single universal control-accuracy value. Finally, an As2Se3 chalcogenide glass molding experiment was conducted, confirming that the apparatus can serve as an open research-oriented platform for PGM process studies.