Mori Seiki in nuclear power station component machining strategy development effort

The Nuclear AMRC was set up in response to the planned construction of new nuclear power stations in the UK and draws on the expertise of the University of Manchester's Dalton Nuclear Institute, the University of Sheffield's Advanced Manufacturing Research Centre, as well as all its industrial partners, which include Mori Seiki together with Areva, Westinghouse, Rolls-Royce, Sheffield Forgemasters, and Tata Steel. The facility aims to raise the contribution of UK companies to the new power station projects from around 50% of their value to 80%. "Each new power station will be equivalent in scale to the 2012 Olympic games, so the potential boost for UK manufacturing will be considerable," explains Stuart Dawson, machining group manager at the Nuclear AMRC. "Furthermore, once we have the expertise in this country, we will be able to bid for nuclear plants constructed elsewhere in the world. The potential is huge China, for example, has plans to build around 80 nuclear power stations." The Nuclear AMRC is installing a Mori Seiki NT6600 mill-turn centre, similar to the machine already operating at the AMRC next door, with the machine supporting research and development into the manufacturing of machined components. "Parts used within the nuclear industry are far larger and heavier than those used in aerospace," Mr Dawson adds. "Shafts can have a length to diameter ratio of 150 to 1 and can be up to 7 m long. This presents some very complex problems associated with the size of the component from the whirling and the out of balance forces encountered during turning and milling operations. "We have been working closely with Mori Seiki to develop a strategy to machine these types of components. Once we have the machine installed, we will produce a methodology which is reliable, repeatable and simple to use, to obtain consistent and high quality results at the push of a button and without human intervention. "AREVA's and Westinghouse's new power stations will be built to standardised designs so, once these are finalised, there will be a requirement for fairly large batches of components. Therefore, time and effort spent in optimising production methods will be well rewarded, making the research and development work we are doing here an important part of producing high quality products and of delivering projects on time." The NT6600 machine will have a spindle bore diameter of 180 mm, three CNC operated travelling steadies, a travelling sub-spindle, bar feed, and a capacity to accommodate 7 m long parts. The machining strategy involves feeding the material through the spindle to allow for over long parts, and machining only short unsupported lengths. As each section is completed, automatic probing will check for accuracy before the bar is fed forward for the next part of the job. The travelling steadies will support the remainder of the component as machining progresses. The NT6600 mill-turn centre has very powerful milling capabilities, enabling the Nuclear AMRC to realistically produce components in one operation, which would have previously required several separate milling and turning operations. Not only does this save a considerable amount of manufacturing time, but accuracy is far better, as resetting operations are eliminated. "We evaluated two or three options for this process, and came down in favour of Mori Seiki's proposal," Mr Dawson reveals. "Its model for service and support has been exemplary, as has the level of engagement provided by its employees. Its track record with the AMRC was a major factor in our decision, and Mori Seiki gets top marks for its ongoing involvement from its regional offices, which are located 200 metres away on the Advanced Manufacturing Park." The work being done on the NT6600 is just one of the projects in which Mori Seiki is involved. The company is also supplying a NMV5000 vertical machining centre for research into the production of smaller parts, such as pump bodies up to 300 kg in weight. Steve Finn, vice president sales for Mori Seiki (UK) adds: "We are absolutely committed to the regeneration of UK industry and are proud to support the Nuclear AMRC. The opportunity provided by the construction of new nuclear power stations within the UK offers a window for growth which will generate employment for years to come and put British companies at the forefront in the renaissance of the nuclear industry."