Fraunhofer Institute for Production Technology IPTResearch project "EffiMaIR"
Manufacturing high-precision glass optics more efficiently with innovative machine technology and digitization
Complex glass optics are indispensable in many high-volume applications. They can be applied in cameras, sensor and automation solutions, semiconductor-based optoelectronics, laser technology and quantum technology. Demand is growing particularly strongly in the field of infrared optics, which are used, for example, in driver assistance systems and thermography.
German optics production cannot keep up with demand
Suppliers from Asia currently dominate the production of precision optics. The high demand cannot be met in Germany because local optics production is too slow, expensive and limited. In addition, the conventional method of manufacturing optics by grinding and polishing is associated with a high loss of valuable resources.
Precision molding: a promising process with potential for optimization
Precision Glass Molding (PGM) is an attractive alternative method for manufacturing precision glass optics. In this process, a heated glass blank is molded between two mold inserts. In contrast to conventional machining processes, PGM is resource-efficient and offers great potential for automation and process scaling. However, the isothermal heating process currently takes about 20 minutes and offers many opportunities to further increase efficiency.
Economical mass production of high-precision optics
In the "EffiMaIR" project, the Fraunhofer IPT and Vitrum Technologies GmbH are developing a new machine technology that will further increase competitiveness in the mass production of precision optics. The innovative technology optimizes temperature control, increases the degree of automation and introduces a process for external fine cooling of the optics. Production cycle time is reduced by approximately 50%, and the improved temperature control significantly reduces scrap rate and correction. Pollution emissions are reduced by 96% and costs by 54%.
The research team demonstrates the new technology using chalcogenide glass lenses. This glass, one of the most challenging types of glass, consists primarily of germanium, arsenic and selenium and is used in infrared applications. Chalcogenide glasses are formed at low temperatures in the range of 200 to 300°C and are very sensitive to temperature changes: Deviations as small as ±1°C result in measurable differences in material behavior.
New heating concept especially for infrared glass
Current forming processes use infrared lamps for radiant heating. However, these are inefficient for chalcogenide glass. The new concept is based on "hybrid forming", a combination of isothermal and non-isothermal process control. The research team combines infrared heat radiation with conduction and convection, which allows for more homogeneous temperature control. With this mix, the new process also takes into account the specific behavior of infrared glass.
The improved temperature homogeneity during the heating, forming and cooling phases increases the geometric accuracy of the optics. The new machine technology therefore promises no loss of shape accuracy despite shorter cycle times.
Algorithms and Simulations for Optimized Processes and Shorter Cycle Times
Process optimization requires accurate models and simulations that take into account all key parameters and help select the most advantageous strategies. To model heat transfer phenomena, the team relies on the use of artificial intelligence, specifically machine learning with limited memory. An algorithm that combines analytical rules and empirical data is integrated into the machine's control system.
The mechanical force that is progressively increased and applied to the lenses during the forming phase is modeled by the project team using FEM simulations. They also use these simulations to determine the maximum possible increase in force without glass breakage. The cooling phase is also redesigned using FEM simulations to remove the formed lenses from the mold inserts earlier and cool them in batches in a special chamber. This allows the molds to be reused more quickly and speeds up the next molding process.
Project partners
- Vitrum Technologies GmbH, Aachen (coordination)
- Fraunhofer Institute for Production Technology IPT
Project Management Agency
Project Management Jülich
Funding
The "EffiMaIR" project is funded by the European Union and the state of North Rhine-Westphalia as part of the ERDF/JTF program NRW 2021-2027.
Funding code: EFRE-20800221
