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06/02/2007 Direct pressing of optical lenses CERATIZIT takes part in the EU project ’Production 4µ’

What do digital cameras, mobile phone cameras, night vision devices, the automotive industry and medical systems have in common? They all need an optical surface: a lens. In the framework of the EU project ’Production 4µ’ CERATIZIT helps Original Equipment Manufacturers (OEMs) of glass lenses to reduce costs. Rather than manual processing in various steps, time-saving moulding technology is applied using precision blank presses.

For the high-quality lenses requested by producers of information and communication technology even today frequently glass rods are first produced and subsequently sawn into pieces. On their way to becoming a finished lens the singular glass pieces then have to be ground and polished, which represents a time-consuming and costly procedure.

CERATIZIT contributes to the EU project ’Production 4µ’ with carbide tools for precision blank pressing, which are able to directly mould glass lenses. In this procedure glass preforms called ’gobs’ are put into upper and lower forms (pressing stamps) which are made of carbide and heated up to 700°C in inert gas. In this manner the glass becomes tough and can be formed. The profile of the lens is now transferred to the glass by the carbide tool or pressing stamp. After cooling down the lens is ready for use without any further operations. This saves time and money.

Nano metal for maximum requirements
Dr. Michael Dröschel, development engineer for industrial wear parts at the CERATIZIT Reutte site says: “One of the reasons for the development of such a procedure is the continuously growing demand for high-quality glass lenses on the part of the information and communication technology sector. Some time ago for example mobile phone cameras had a very low resolution. The requirements regarding the optical lens used were not very high so that a plastic lens was sufficient. As glass is characterised by excellent optical properties and the geometries are becoming increasingly complex, the originally used plastic in optical precision components is being replaced more and more by glass. Only in this way is it possible to attain the higher resolution of the images requested by end-users.“

In order to be able to apply the moulding procedure the carbide has to meet maximum requirements. “The microstructure of the carbide has to be homogeneous in the entire component. “To guarantee the optical standards for precision blank moulding (roughness <1nm = 1/1,000,000 mm), we apply nano carbide grades with grain sizes <0.2 µm. The challenge: despite the high temperatures up to 700 °C corrosion of the carbide with the glass must not occur,” explains Dröschel. CERATIZIT delivers the carbide tools in preground condition to the customer.

EU project ’Production 4µ’
Since May 2006 CERATIZIT has taken part in the EU project ‘Production 4µ’. The project title stands for ’Production technologies for micro systems’ and refers to a four-year European research project with the participation of a total of 20 key companies. The goal of the project is to establish a manufacturing procedure for the bulk production of glassmicro-products in Europe. Furthermore, an additional improvement in product planning and the possibility of application in other micro-structure applications or other materials is aimed at later on. In this context the standardisation of the new procedures is important.

“We firmly believe that the procedures will be well-established in the European market as innovative key-technologies once research is concluded,” says the carbide expert Dröschel underlining his optimistic view of the future.