Coating systems for precision glass molding tools

For the production of optical components with complex or micro geometries, the most suitable technology to replace grinding and polishing is precision glass molding. In this single-step replicative process, heated glass blanks are molded into complex optical components using ultra-precise forming tools. In practice the molds have a short lifetime, which can be attributed to the great thermal and mechanical stresses and to the chemical interactions between the hot glass and the mold surface. In order to increase the lifetime, protective coatings must be applied on the molds. As a result of the unique stress profile, the standard Ti, Al or Cr-based coatings widely used for cutting tools are inappropriate for this application. Instead, Pt-based coatings are preferred.