Cranfield has BoX to grind

CranfieldUniversity has launched an ultra precision large optics grinder that could significantly reduce the time taken to produce mirrors for telescopes.

Cranfield designed and developed the BoX (Big OptiX) machine in response to the significant increase in the number of large mirror segments required for the next generation of extra large telescope (ELT’s), such as the James Webb Space Telescope, which will replace the Hubble Telescope at the end of the decade.

Pat McKeown, OBE, FREng Professor Emeritus at Cranfield unveiled the machine at the MACH2006 exhibition this week.

Current manufacturing technologies for producing 1-2 metre ultra precision mirrors have processing times of hundreds of hours, meaning the time it takes to process a single ELT would be hundreds of years. Cranfield’s BoX machine radically reduces the processing time for these mirrors to hours as opposed to days.

Professor Paul Shore, Head of Cranfield’s Ultra Precision Engineering Centre, said, “Our goal was to engineer a machine with very high dynamic loop stiffness that would enable ultra precise large free-form optics to be rapidly ground with serial production capability, minimal sub-surface damage, all at minimum cost. We have achieved this whilst retaining high precision design principles. The BoX machine is a great achievement for both Cranfield and for the UK manufacturing industry.”

The new machine is a simple box shape, allowing cost effectiveness whether scaling up or down. The first machine permits parts up to two metres in diameter to be ground, with plans in place to develop the machine to provide a rapid and economic solution for grinding large off-axis aspherical and free-form optical components for industry. The joint UK Research Councils Basic Technologies Programme funded the project with additional support from the McKeown Foundation for Precision Engineering and Nanotechnology.

Cranfield said it aims to re-establish the importance of UK manufacturing capability in the field of ultra precision technology with the BoX. Many of the machine’s parts are produced in the UK and the concept has now been patented by CranfieldUniversity.