New casting technology aids submarine propulsion
Cti has built a world-wide reputation with users and suppliers of castings by providing practical support which benefits both parties. It is now well-established that the operational resources within Cti can improve competitiveness with little or no risk and at lower cost than would otherwise be possible. Meighs Ltd., a leading UK supplier of specialist alloys and castings, foresaw the available opportunities at a very early stage, and the close, proactive relationship with Cti that has existed for many years reflects the vision and foresight of their management. Activities such as:
- Training of key managers, and latterly 2 modern apprentices;
- Development of technical skills, for example, in the pouring of super-duplex stainless steel;
- Validation of simulation software to justify its procurement for high-integrity naval valves and fittings;
- Evaluation and implementation of CNC patternmaking for ‘reverse engineering’ of naval valves, fittings, strainer bodies, etc;
- Analysis of new market opportunities, in wave power, for example;
all bear testimony to the company’s endeavour and willingness to adapt to change and to adopt new technology.
For security reasons the Astute-class submarine is shown here as an artists impression (by kind permission of BAE Systems)
Meighs’ role in a project to develop the propulsor for the Astute-class submarine underlines their progressive culture. Based on aero-engine technology, the development by Rolls-Royce of the Astute propulsor for prime contractor BAE Systems required concurrent engineering to be deployed throughout the supply chain to meet a programme of design, project management and delivery that was reduced from 42 months to 27. Meighs recognised that Cti had a capability in its Patternless® Process to assist them, as a consequence of their involvement in the European ‘Craft’ project that developed the technology. Ideal for producing prototypes, one-offs or small volumes of castings, the Patternless® Process produces sand moulds by directly machining blocks of sand, rather than a pattern – the manufacture of which is both costly and time-consuming. In this case the technology was used by Cti to produce moulds for prototype propulsor stators and rotors. The moulds were shipped to Meighs and poured in a nickel-aluminium-bronze alloy using methods developed by Meighs which exploited their capabilities with process modelling (simulation) software. By this means, it was possible to compress optimisation of the design and manufacturing process and to verify the complete manufacturing strategy along the supply chain.
Sand mould for propulsor stator being machined using the Patternless® technology
As John Fowler, Marine Materials Specialist in Rolls-Royce Marine attests: “the time from CAD model to prototypes was 6 weeks using the Patternless® Process, whereas our experience teaches that it would have been 6 months by the traditional route”.
Data captured during the prototyping phase, especially on contractions, enabled Cti to manufacture the production tooling on its large-scale machining systems in a shorter time-frame and with greater confidence that the production castings would be precisely to form. The pattern and mould pouring technique required customised moulding boxes which were also designed and manufactured by Cti. This resulted in a reduction in machining stock of 60%, an immense benefit to Meighs as they were supplying the stators and rotors fully machined and tested.
Meighs Ltd is based in Stoke-on-Trent and employs 60 people. Its Chairman and owner, John Halliday, says: “This was a big order for us, and I have no doubt that, even if we had won it alone, we would not have performed as well as we did had there not been such a great relationship between our people and Cti’s. The order secured 12 jobs. Mind you, it cost us £300k in time and money to get it – and we spent more than £50,000 with Cti – so it was a big risk but it has shown the benefit and the high level of functionality that can be achieved by working in an integrated team. Cti has done a lot of work on fixed-pitch and controllable-pitch nickel-aluminium-bronze propellers and shown that the Patternless® Process offers huge benefits, particularly for naval propellers. We are exploring with them the opportunity of setting up a UK-based consortium to deliver propellers – and other nickel-aluminium-bronze castings – to the MOD supply chain using this technology. There has to be a strong case for such strategic components to be sourced in the UK. The resources available at Cti – especially their capital facilities – are immensely valuable to UK companies. We have been able to leverage these to create a capability which more than matches that of our competitors overseas, and if that means working co-operatively with our UK competitors to achieve simultaneously what is best for this business and the UK, then I’m up for it”.
Cti has installed a large-scale (3.6 x 3.6 x 1.2m working envelope), high-speed, 5-axis, precision machining facility for manufacturing short lead-time patterns and for the Patternless® Process. This investment and the support provided to both Meighs Ltd and Rolls-Royce was made possible through the Rapid Product Innovation Strand of the Advanced Metals Technology Initiative (AMTI) funded by the Dti, Yorkshire Forward and the European Union through the South Yorkshire Objective 1 Programme. The AMTI project is managed by NAMTEC, the National Metals Technology Centre.