This article first appeared in MWP Advanced Manufacturing on 26th June 2012
ELE Advanced Technologies, which specialises in applying non-conventional machining techniques to the production of industrial gas turbine components used in aircraft and power generation, has invested £2m in an automated VIPER grinding cell at its Colne factory.
The equipment is devoted to high-efficiency machining of complex fir-tree root forms and shroud end features on nickel alloy turbine blades, compressor blades and guide vanes. Customers include Rolls-Royce, Avio, Pratt & Whitney, Siemens and Alstom.
Peter Calderbank, operations director at ELE, said: ‘We have traditionally used conventional creep feed grinders to manufacture industrial gas turbine components. While this method is efficient for large-volume production, the market is increasingly demanding smaller batches, delivered just-in-time. This means that we need to introduce more flexible, rapid changeover technology to bring down manufacturing costs for shorter runs, hence our investment in VIPER [very impressive performance extreme removal] grinding. Set-ups are quicker and completed off-line, lead times are shorter, the amount of work-in-progress is less and tooling costs are lower, leading to much more economical machining of high accuracy features in exotic alloys.’
The automated process at ELE is based on a Makino 5-axis A99e machining centre configured for creep-feed grinding using small, profiled wheels exchanged from the tool magazine. The turnkey cell includes equipment for continuously dressing the grinding wheels, an Erowa palletised workholding system and a Fanuc 6-axis robot for exchanging fixtured components automatically.
More features can be ground in a single set-up on a VIPER machine than on a conventional creep feed grinder, saving refixturing time and promoting higher accuracy and repeatability. Typically, conventional grinding of root and shroud features on a nickel alloy casting requires four separate operations on CNC grinders, plus there is a significant amount of handling time. The same component can be completed on the Makino A99 in two operations and speed of manufacture is increased further by the higher metal-removal rate.
Another useful benefit of VIPER grinding on a machining centre is that other tools can be brought into use from the same magazine that houses the grinding wheels. So, for example, if additional metalcutting operations such as milling and drilling are required, these may be completed in the same cycle without manual intervention.