Aluminium mirror polishing: No longer a challenge

Kemet International has revolutionised the process of aluminium mirror polishing with the launch of their Kemox SF slurry, which has quickly proven to be the ideal solution for achieving a flawless finish before superfinishing. This breakthrough was recognised by Professor David Walker, a renowned expert in Ultra Precision Surfaces at Huddersfield University, during the polishing of a 480mm diameter aluminium mirror for the LOCUS project.

The LOCUS project is a proposed space mission designed to observe the Earth's atmosphere at grazing incidence. This method allows for longer path lengths to measure pollutant chemical species with high precision. The project is based on an off-axis Cassegrain telescope design, intended for cryogenic operation in both the Terahertz (microwave) and near-infrared regions, which requires a highly polished, precision surface for optimal performance.

The mirror’s fabrication began with CNC milling, creating an off-axis parabolic surface. It was then pre-lapped to achieve a uniform grey surface. However, when a range of polishing slurries were tested, none could produce the necessary uniform polished finish. Many of the slurries tested crystallised too quickly, leading to clogging in the dispenser system and causing delays in the process.

Kemet International stepped in to address these issues by providing their Kemox SF slurry, specifically designed for aluminium polishing. This innovative slurry not only delivered a smooth, uniform polished surface but also significantly reduced the polishing time. Importantly, Kemox SF also solved the problem of slurry crystallisation, ensuring a smooth, uninterrupted polishing process.

After the initial mirror polishing was complete, the mirror underwent a superfinishing process using Kemet’s COL-KNC non-crystallising colloidal slurry. This advanced slurry allowed for the final surface texture to reach an impressive 6nm, meeting the rigorous requirements of the LOCUS project.

From initial consultation with Kemet to delivering a fully finished mirror took only two weeks, showcasing the efficiency and expertise that Kemet brings to the field of precision surface finishing.

If you believe your project could benefit from Kemet’s 80 years of expertise in precision surface technology, get in touch with their team today. Tel: +44 (0) 1622 755287 or sales@kemet.co.uk

With Kemet’s advanced polishing solutions, even the most challenging aluminium surfaces can now be flawlessly mirror-polished with ease.

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