Fraunhofer Institute for Production Technology IPTResearch project "CENTiMO"
Demand for complex yet low-cost glass optics is growing within the sectors of lighting technology, automotive engineering, and in the areas of renewable energy. However, European companies are continuously being confronted with the dual challenge arising from the trend towards increasingly complex geometries coupled with intense pressure on market prices.
Still, the state-of-the-art approach to manufacture complex shaped glass optics is not efficient enough to meet the requirements of mass production sufficiently. The process requires large amounts of energy and manual work which results in a very time-consuming and expensive process. Besides, a large amount of glass is wasted and the moulds only have a limited lifetime.
Therefore, the European SMEs are pulling for new technology developments enabling them to build up a new and improved process chain which allows for an efficient and economically viable glass optic replication.
The key to success in developing an efficient integrated production chain for complex optics is to mould optics directly from a gob of molten glass. This way, reheating of the glass, as it is currently necessary, is obsolete and saves large amounts of energy. Due to the precise cutting of glass gobs no subsequent mechanical processing is necessary and the amount of glass waste will be reduced to almost zero. Furthermore, this process can be fully automated which makes it fast and stable. In order to provide the SMEs with this efficient and economically viable production chain, extensive developments are necessary.
The project CENTiMO will start with a detailed analysis of melting, gobforming, and the moulding process. Based on this, the project partners will develop a suitable melting and gobforming process which is able to deliver gobs that can directly be moulded into glass optics. At the same time the glass moulding process will be developed. New mould materials will be evaluated in order to achieve the required quality and mould lifetime. Finally an evaluation and qualification of the developed processes will give decisive feedback for the improvement of the whole process chain.
Motivation
In the future there will be LEDs with even brighter light heads that can be used more flexible and individually. As a consequence of this trend optics have to withstand higher thermal loads. Polymer optics have a limited thermal resistance compared to glass optics and therefore only work to a limited extend. In comparison, glass offers some unique properties like an excellent heat and scratch resistance which leads to improved products. Therefore, glass is the material of choice for many future LED applications.
Technological trend toward glass optics
The demand for complex low-cost glass optical components is not only growing within the lighting market but also in many additional sectors like automotive engineering, renewable energy, and medical technology. Based on this strongly growing demand, the overall goal of the CENTiMO project is to develop a new process chain which allows for an efficient and economically viable glass optics replication.
The Technology
The overall technological goal of CENTiMO is to enable the cost effective manufacturing of complex glass lenses through blank moulding. In order to achieve the overall goal two main developments are necessary and will be worked on in this project.
Glass melting and gob forming
In order to enable the moulding of optical components directly from the melt a suitable glass melting and gob forming process is needed. LED optics usually require small glass optics combined with frequently changing glass types. Therefore, very flexible melting furnaces with capacities of up to two tonnes of glass per day are needed and will be developed within this project. On the other hand, forming of glass gobs from a melt is a very common technology, especially in the container glass industry (e.g. bottles, jars, drink ware, and bowls). However, the gob forming for small glass weights combined with high production speeds and optical quality, which is used for manufacturing of LED optics, is currently not available. The project partner Glass Service will perform extensive modelling work on glass melting and gob forming. The results will provide large insights into the process which are absolutely necessary in order to optimize the processes. Based on the simulation results optimized melting and gob forming equipment will be developed.
Glass moulding
The second core development of CENTiMO will be the moulding process. This development will focus on the evaluation of different mould materials and coatings. From the research point of view it will be investigated in detail which materials are suitable for the moulding process and which properties of the materials have positive or negative influence on the process result. Since the wear strongly depends on the glass material which is used, the different mould materials will be evaluated using different very common glass types. Together these developments will extend the lifetime of the moulds and increase the reachable form accuracy. In order to further increase the quality of the moulded LED optics, extensive FEM simulations will be performed to compensate for the high shrinkage of the glass during the moulding.
The entire RTD work accomplished within the project will be conducted based on the initial requirements analysis and demonstrator definition. This will ensure that the developments will be executed strictly application oriented considering the SMEs’ needs as well as the market needs represented by the end user Osram.
CENTiMO process chain compared to the state-of-the-art approach
Funding organization
European Commission
Project coordination
Fraunhofer Institute for Production Technology IPT
Dipl.-Ing. Dipl.-Wirt. Ing. Holger Kreilkamp
Steinbachstrasse 17
52074 Aachen
Germany
Project partner
The CENTiMO consortium consists of a multidisciplinary group of partners located all over Europe, having very different roles and dealing with different topics within the project.
- Fraunhofer Institute for Production Technology IPT
- Füller Glastechnologie Vertriebs GmbH
- Glass Service AS
- Industrial Analysis Limited IAL
- Officine S.L. srl.
- Osram GmbH