New Casting Technology Aids Submarine Propulsion

CT 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 CT 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 CT 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 artist’s impression (by kindpermission 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 CT 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 CT 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.

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 CT 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 boxeswhich were also designed and manufactured by CT. 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 CT’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 CT 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. CT has done a lot of work on fixed pitch and controllable-pitch nickel-aluminium-bronze propellers and shown that the Patternless® Processoffers 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 MODsupply 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 CT 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.