Glass is an indispensable material for numerous components in electronics, the semiconductor industry and sensor technology because it is light, scratch-resistant, temperature-resistant and very stable. With a thickness of only a few millimeters, such thin glass is the preferred material for high-quality automotive interiors, such as center consoles, rearview mirrors, door elements and speedometer units. In more than 50 percent of all thin-glass components for the automotive industry, the glass surfaces are functionalized by introducing extremely fine structures. These modifications are diverse: they range from improved, pleasant haptics to water-repellent and reflection-reducing surface properties.
Two main processes are currently used to structure the surface of thin glass. The most common method in industrial practice is chemical structuring. This achieves good results but uses extremely environmentally harmful etching agents such as hydrofluoric acid. The second method is replicative molding: the structures are inserted into the glass surface under very high process temperatures using a molding tool, while the glass is simultaneously brought into its final shape. Replicative molding also provides very good results, but the manufacturing costs as well as the consumption of raw materials and energy are clearly too high to be economically attractive and ecologically sustainable. For example, the wear on the molding tool is so high that it usually has to be replaced with a new one after about every tenth mold produced.
The aim of the research project "EffF3D – Efficient functionalization of 3D-molded thin glass" is to develop an energy- and resource-saving process chain to mass produce complexly molded and functionalized thin glass. The approach is based on two technological pillars: upstream structuring of the glass blanks by laser structuring and subsequent non-isothermal glass forming.
Compared to conventional manufacturing routes, the new process chain will reduce energy consumption and CO2 emissions by over 60 percent in each case. The use of environmentally harmful chemicals can be completely eliminated. The project team is also aiming to significantly reduce production costs: The new method is expected to be around 50 percent cheaper than conventional processes.
In the first phase of the project, the researchers will be working on how to sustainably and economically functionalize thin glass blanks using a laser. The upstream laser structuring process not only eliminates the need for chemicals, it also extends the lifetime of the forming tool by a factor of around ten, according to well-founded calculations. The team's goal is to provide the blanks with haptic, hydrophobic and optical functions of different size scales reproducibly at area rates of up to 1500 cm2/min.
Surface texturing with conventional laser systems is highly accurate, but too slow for mass production. To significantly reduce the time, the team is working with project partner LPKF SolarQuipment GmbH on developing a new tool system that consists of an ultrashort pulse laser with pulse durations of less than 10 picoseconds and ultrafast scanning systems known as polygon scanners. The use of polygon scanners massively accelerates structuring, but it only allows two-dimensional surfaces to be processed. For this reason, the structures are already introduced into the plain, two-dimensional surface of the glass blank before it is formed.
Since the structures are distorted during forming, the project partner ModuleWorks is developing a digital model to compensate for these distortions. To this end, the project team is implementing an FEM simulation of the glass's behavior while it is being formed. The compensation model serves as basis for the path planning of the laser system.
In the next step, the semi-finished, structured glass will be formed into the desired shape by the project partner Vitrum Technologies together with the partners FLABEG Automotive and Saint-Gobain Sekurit Deutschland under industrial conditions using non-isothermal forming. The aim is to achieve a cycle time of less than 100 seconds per glass component with structural distortions of only a few micrometers. Since pre-structured components have never been formed in this way before, one of the tasks in this stage of the project is to find out the ideal process temperature in order to form the glass in the best possible way without damaging the structures.
The team uses selected sensor technology to record process data to obtain as much information as possible about the forming process and make it as transparent as possible. The formed components are then characterized metrologically. In the event of deviations, the structural quality is optimized with the simulation model and further experimental tests.
Finally, the Fraunhofer IPT will analyze the entire process chain using detailed life cycle assessments based on numerous ecological criteria. The team will compare the calculated key figures with those of conventional process chains; in addition, it will also compare the manufacturing costs of the new process chain with those of conventional series production chains.
Upon completion of the project, the team will have developed a prototype laser system and an extension of a thin-glass forming system for use under realistic production conditions. In further research projects, the process chain will be adapted and further developed for numerous applications in consumer electronics, household electronics and medical technology.
The research project "EffF3D – Efficient functionalization of 3D-formed thin glass" is funded by the German Federal Ministry of Economics and Climate Protection (BMWK) within the 7th Energy Research Program of the German Federal Government.
Funding code: 03EN4035A
Project Management Jülich – Research Center Jülich