Photonics West 2017: Smart systems and production processes for large-scale optics manufacturing

Glass Molding: Cost-efficient large-scale production of high-precision optics

According to a study undertaken by the management consultants McKinsey, LED lighting will account for approx. 70 percent of the lighting market by the year 2020. The requirement for complex header optics which direct the light is projected to increase in tandem with the number of LEDs.

Glass optics come into their own wherever particularly high levels of resistance to extreme temperatures and UV radiation are required. The non-isothermal glass molding technique permits these to be manufactured in one single manufacturing step: a pre-portioned glass blank is heated to temperatures of up to 900 °C in a special heating furnace then formed under high pressure within only a few seconds. The short process times along with the fact that no further steps are required for finishing makes this process ideal for large-scale manufacture.

The aim of the ongoing research and development work at the Fraunhofer IPT is to increase the dimensional accuracy of the optics manufactured in non-isothermal glass molding operations. As part of this development, forming tools made of new ceramic materials with particularly long service life are used in manufacturing processes, which have been specially adapted for these tools.

Additional work currently underway at the Fraunhofer IPT focuses on the manufacture of extremely small glass optics, only a few millimeters in diameter. The tools used were high-precision molding tools whose dimensions were calculated by the researchers in Aachen using a specially developed FEM simulation module.

Tools for high-volume infrared optics production

Infrared optics are currently used predominantly in relatively high-end technical equipment and facilities: night vision systems allow drivers to see people and animals even in low light conditions at night. Thermal imagers help building owners and surveyors to detect leaks and cold bridges in buildings.

Until now, infrared optics have been manufactured in grinding and polishing operations or in machining operations which are comparatively expensive. Precision glass molding, in which a preform is shaped in a press under direct influence of heat, can reduce the costs since larger numbers of optical components are formed to specification in one single process step.

The Fraunhofer IPT is scrutinizing and testing all of the main elements involved in precision molding infrared optics from chalcogenide glass – starting with the question as to how the high precision, aluminum alloy can be machined using monocrystalline diamonds. Within a research project, the engineers in Aachen are also developing special wear resistant coatings, which significantly prolong tool life. A simulation model, developed specially for forming chalcogenide glass, permits forming processes to be designed with enormous precision. Even before the very first pressing trial, all of the process parameters can be determined, thereby slashing both the outlay otherwise required for process development and the amount of scrap generated.

Smart Wearables: Digitization of manufacturing processes help to increase product quality

Looking inside the “black box” of the machine is just one more component of the new concepts with which the researchers from Fraunhofer IPT are currently optimizing the mass production of optical lenses. To be able to benefit from the digital information from all process steps, they have developed independent, web-based software. This software runs on standard devices such as laptops, smartphones and smart glasses, and requires no installation. All users – from developers to quality control inspectors – have access to a shared process database.

For the first time, this process can now be followed on a tablet PC, where a simulation shows in real time how the blank conforms to the shape of the tools that are pressing it and how the lens then slowly cools. At the same time, diagrams supply information about where the various forces are acting and how the temperature changes. First studies show how data can be used to optimize the whole manufacturing process – from simulating the process, making molds and coating tools to shaping parts and quality testing the finished optics. Next, the Fraunhofer researchers want to use real-time analysis of process data to ensure that the required quality is achieved and set up an automatic alarm system for when deviations arise.

Contact

Fraunhofer Institute for Production Technology IPT
Holger Kreilkamp
Steinbachstrasse 17
52074 Aachen
Germany
Phone +49 241 8904 -454
holger.kreilkamp@ipt.fraunhofer.de
www.ipt.fraunhofer.de

This press release and a printable photo are also available on the Internet under
www.ipt.fraunhofer.de/en/Press/Pressreleases/20170130_large-scale-optics-manufacturing.html

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