Manufacturing Facilities at Glyndŵr University, St Asaph
Glyndŵr University, St Asaph is well-equipped with a range of facilities for both R&D and contract-manufacturing of precision optics. A variety of materials can be processed up to 1.6m square. Surfaces that can be handled are convex, concave, flat, spherical, aspheric or freeform. Capability exists for CNC milling in smaller sizes, including pocketing for light-weighting.
The core facility comprises three Zeeko CNC polishing machines:-
- Zeeko IRP1600 – capacity 1.6m x 1.6m, upgradeable with modification to 2m
- Zeeko IRP1200 – capacity 1.2m x 1.2m
- Zeeko IRP600 – capacity 600mm diameter, 600 x 350mm rectangle
These machines support spiral, adaptive-spiral, raster and pseudo-random tool-paths. Special algorithms have been developed for polishing to the extreme edge of a part. Processes available include pre-polishing of ground parts, corrective-polishing using metrology feed-back, and “grolishing”. This last comprises a family of bound and free abrasive processes intermediate between grinding and polishing, used to remove bulk material and smooth mid-spatials from CNC grinding.
The IRP1200 also supports fluid-jet polishing which can, for example, remove turning marks from diamond-turned surfaces.
Full aperture interferometry can be performed with the part in-situ on the IRP1200 and 1600 machines, both of which give a clear view of their respective test towers above.
|Main Production Hall
This general view looks towards the Zeeko IRP1600 under the 10m high Optical Test Tower at the rear, and the IRP1200 to the right. At the near left corner can be seen a mirror segment under its protective cover.
The area is air-conditioned, and is operated under the 5S quality assurance protocol.
|Zeeko IRP1200 CNC polishing machine
This machine can polish a wide range of surfaces up to 1.2m square, and is located under its own test-frame. A simultaneous phase interferometer is mounted at the top of the frame, used for in-situ measurements of components on the machine turntable. This avoids the need to de-mount and re-mount parts at every measurement cycle. The IRP600 CNC polishing machine can be seen in the background.
Zeeko IRP1600 under the Optical Test Tower
The IRP1600 and test tower are mounted on a floor reinforced by nine 7.5m deep pilings, and provide a stable and integrated polishing and interferometry facility. The machine is upgradeable to 2m capacity by retro-fitting longer encoders and ball-screws.
Simultaneous interferometry is used to freeze vibration. Dimensional metrology of the null test configuration is performed using a laser-tracker, mounted on the tower. The temperature-profile up the tower, together with the external and general lab temperatures, are automatically data-logged.
Computer-controlled Test Rig.
This is furnished with a standard Zeeko tool-spindle and is available for process trials on flat witness parts. Its purpose is predominantly to optimise slurries, pads, speeds and feeds, on new materials. The Test Rig is limited to simple raster tool-paths on flat parts. It is, however, particularly attractive for trials using bound or free diamond abrasives, in cases where it is required not to contaminate another machine. Abrasives can be delivered by hand, or using a digitally-controlled peristaltic pump system.
Fluid jet polishing on the Zeeko IRP1200
This technique uses a high-pressure jet of polishing slurry that directly removes
material from a surface by kinetic energy, and with no physical tool.
Fluid-jet is particularly powerful for removing diamond-turning marks, for addressing highly localised features (e.g. edges), or to polish areas that can’t easily be reached in any other way (e.g. insides of holes).
Bonnet polishing on the Zeeko IRP1200
A 50cm diameter parabolic mirror is being CNC polished for a major UK satellite provider.
The Zeeko machines are highly versatile in polishing a wide range of surface forms – from flat to off-axis aspheres and free-forms. The processes have been further developed within the national Facility.
This CNC precision grinder has a capacity of 500mm diameter, and is used for profiling parts before polishing on other machines such as the Zeeko machines.
The grinding machine is also used for machining of light-weighting rear pockets
Classical Optics Shop
This is furnished with classical motorised polishing spindles and other equipment. It provides a wide range of tasks, complementing the CNC machines, including:-