Sensing a way into the future

Better measurement and advanced instrumentation are helping companies become more competitive by reducing scrap, raising quality and slashing set-up times.

BAE Systems, the UK’s partner in the production of the Eurofighter, has spent £2.5m to ensure that the aircraft’s fuselage will be perfectly aligned. It must not deviate by more than 12mm over the aircraft’s 15m length. The aim, says BAE, is to reduce drag which could knock 2%-5% off the aircraft’s fuel bill and give the pilot maximum flying performance.

BAE’s Automated Alignment Facility uses two lasers and nine computer-controlled jacks to marry up the three separate fuselage sections. With the first two production Eurofighters built at the Warton plant the company achieved a deviation along the fuselage of less than 2mm – six times better than required. Deviation across the aircraft from wing tip to wing tip is just 0.5mm, well under the design tolerance of 1.5mm. And BAE reckons that by the time it builds the 20th aircraft, fuselage assembly time will be down to just half a shift, compared with three to five days using traditional assembly tooling methods.

The alignment facility is unique in using two-laser measuring systems working together. It won a prize in the recent Metrology for World-Class Manufacturing Awards, sponsored by the National Physical Laboratory (NPL), instrumentation company Fluke, and the Engineering and Marine Training Authority.

NPL estimates that accurate measurement contributes around £6.5bn to the UK economy and is a key enabling technology for manufacturing industry. The awards are one of a number of government-backed initiatives in the UK to encourage innovation in measurement and to ensure that the latest developments are transferred from university laboratories to industry.

Measurement, or more widely sensors and sensing, was one of the areas identified by the Foresight programme as vital to the future economy of the UK. Use of better measurement and advanced instrumentation would help companies to improve competitiveness by reducing scrap, raising quality and cutting set-up times. And university research into new sensor technologies would enable UK instrumentation firms to establish global markets for advanced measuring equipment.

So when the Engineering and Physical Sciences Research Council (EPSRC) decided in 1996 to resurrect the idea of Faraday Partnerships to help turn university research into new products and innovations in industry, sensors was one of the areas chosen. Four pilot partnerships were set up, each backed by £1m of government cash. They cover sensors, 3D data capture, packaging, and electromechanical assemblies. NPL and instrumentation research organisation Sira run the INTErSECT Faraday Partnership on sensors. So far, says Professor Richard Brooks, Sira’s chief executive, INTErSECT has turned its original £1m EPSRC grant into a portfolio of hardware and software projects worth £12m that brings together nine universities, 25 large companies and 30 small firms.

‘We went to the major users of instrumentation, companies like Rolls-Royce, Corus, and GlaxoSmithKline, and asked what instrumentation they needed, but didn’t have or could not get commercially. Then we figured out why those products didn’t exist and pinpointed areas for research.’

The biggest gap was in gas sensing, Brooks says. ‘Ideally industry would like to have something you see on Star Trek – a hand-held instrument that will tell you what gas is in front of you and how much of it there is.’

Thanks to INTErSECT, science fiction may soon become reality. Two projects involving Lancaster and Southampton universities are looking at gas analysis using infrared. And another set of INTErSECT projects is under way on the problem of monitoring vehicle emissions at the roadside.

Another gap identified by NPL and Sira was for high-temperature measurement, particularly in gas turbine engines and steel making. As a result, Warwick University and Manchester University are now working with Rolls-Royce, Corus, and the privatised defence research agency Qinetiq on a sensor for measuring the efficiency of flames in engines and furnaces.

‘A blue flame is an efficient flame,’ explains Professor Bryanston-Cross in the school of engineering at Warwick. His team has developed an array of 40 fibre optic sensors mounted around the combustor of a gas turbine engine to measure flame efficiency. ‘Ultraviolet light is a characteristic of the chemical radical produced by a burning flame and so is a measure of its efficiency,’ says Bryanston-Cross.

The device is about to undergo trials. It can also be used to measure the efficiency of the flame in an internal combustion engine.

There is a similar optical sensor already on the market for measuring flame efficiency, says Bryanston-Cross. ‘But it is horrendously expensive, costing about £100,000. We are talking to a small UK instrument company about making our sensor, and I think we’ll get the price down to £10,000.’

Other INTErSECT projects include traceable acoustic emission at Brunel University – ‘listening to the creaks and groans of process plant and turning them into a metrological process’, says Brooks. City University is working with Corus, BNFL and Kidde International on a ‘smart brick’ for detecting wear in furnace linings. The idea is to embed optical fibre temperature sensors in the refractory lining of a furnace – as the lining wears, the temperature rises. Lancaster University is working with Corus on the electromagnetic sensing of the crystalline properties of steel as it is being made. But metrology isn’t just for big companies, says Jerry Benson, director of technology transfer at NPL, as the recent On Machine Measurement Project has shown (The Engineer, 16 November). The scheme has funded the loan of state-of-the-art commercial measuring equipment from a number of suppliers to 30 small engineering firms in the West Yorkshire region, resulting in savings of more than £200,000 in scrap and set-up times and potential new business of over £900,000.

The companies have been able to try out for free some of the latest commercially available measuring devices, ranging from surface texture instrumentation to digital gauges, machine tool spindle probes and machine calibration systems. So far, about half of the firms have been so impressed with the benefits that they have bought the equipment, which has ranged in price from £2,000 for a ballbar system for calibrating a machine tool to £7,000 for a laser alignment system.

The scheme is being rolled out early next year to Bristol (for the aerospace industry) and St Helens (automotive) and is likely to go national soon after, to take in industries such as printing and food manufacture.

Meltham Mills Engineering of Huddersfield is one of the scheme’s many success stories. The firm makes gears and transmission parts for companies such as JCB and Rexroth. It has a turnover of about £5m, and employs 70 people. Works manager Steve Alcock has just been asked to pay for the Renishaw spindle probe he has had on loan for 90 days. He has been trying it out on one of his three machining centres to reduce set-up times. The probe records the position of the workpiece, so eliminating the need for expensive jigs and fixtures to hold the workpiece, allowing simple clamps to be used.

But will Alcock buy the probe? ‘Oh absolutely, yes. It’s paid for itself three times over. It must have saved us £20,000.’ He says customers will pay the rate for machining time on their gears, but they don’t want to pay Meltham for making jigs and fixtures. ‘This probe means we don’t have to,’ says Alcock. As a result, Meltham has been able to take on a job that could be worth £500,000 a year. ‘We’re definitely thinking of buying another other probe,’ Alcock says.