Precision glass molding: towards a cost-efficient production of glass lenses using a multi-cavity approach

Precision glass molding of optical lenses is similar to plastic injection molding, although a few fundamental differences exist between the two. One of the major disadvantages of the glass molding process over injection molding is the cycle time. The cycle time required for an injection-molded plastic lens can be less than 30 seconds, whereas an equivalent glass-molded lens may take anywhere from 15 to 30 minutes. Apart from the longer process times, the higher temperatures required by the glass molding process reduce the tool's lifetime thereby increasing the production costs. This paper presents a new glass press mold tooling that utilizes a multi-cavity approach with interchangeable mold pairs, enabling the production of multiple lenses in a single molding cycle. Further, the molding process as well as the tooling are optimized to achieve uniform accuracy and optical quality of the glass lenses across the mold plate.