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Neil Warner

	Friday, February 18, 2000

Lasers cutting
into industry

RESEARCH: Computer-controlled lasers are finding their way into Irish manufacturing plants thanks in part to the efforts of the National Centre for Laser Applications at NUI Galway. The centre is involved in a new European Regional Development Fund programme to transfer this advanced technology to industry. It also has more than a decade of experience in helping Irish firms to develop manufacturing processes and techniques around lasers, explained Mr Tony Flaherty, a senior research scientist at the centre.

"Lasers are a real key technology in product and process development," Mr Flaherty said. They can be used for very detailed welding, cutting, drilling, arking and for surface treatments such as anodising, polishing and "roughing".

Lasers seem quite an exotic technology and more in keeping with science fiction than manufacturing reality, but the integration of lasers with advanced computing technology has brought a remarkable degree of control to these devices, accuracy of particular value for example to medical device manufacturers.

The west enjoys one of the highest concentrations of these companies in Europe, Mr Flaherty stated and many of them are on the centre's books including Boston Scientific, Medtronic-AVE and Donegal Health Care to name a few. The centre earns about £100,000 (#126,974) a year from Irish-based manufacturers, more than half of them in the medical devices area.

About 40 per cent of its income is from industry, he said, with the remainder coming from research grants. It employs 10 full-time staff and typically about six students who work on research projects towards degrees over a two or three-year period. The centre has a capital infrastructure worth about £3 million and includes about 10 industrial lasers. "These would cover the main industrial uses. They are powerful lasers used by industry for cutting, welding and working materials," Mr Flaherty explained.

"The main focus of the centre would be applied research, directed towards industry," he said.

This ranges from small batch work, overcoming problems with existing systems, right up to the complete specification and commissioning of a new laser system.

"Our typical interaction with a company is a client will phone us up" looking for an answer to a problem or a new idea, Mr Flaherty said. A company might want to see if laser welding might be a better option to the existing use of adhesives to bond two items and the company needs to know if it will work.

"We try to take things along on a step-by-step basis," he said. Researchers at the centre would set up test trials to see if laser welding was possible, taking into account weld quality and product throughput.

"If the answer is yes then we can go on to process development."

The feasibility trials are useful because they involve only a small investment in time and money, he said. "A lot of times people are concerned about the capital cost of lasers," he said, but there were many advantages, chief among them the ability to automate a process. "The laser is an ideal tool for automation," he said, and could help increase manufacturing volumes while reducing consumables, for example the adhesives mentioned in the example above.

A typical industrial laser might cost tens of thousands of pounds but when integrated with machining equipment and computers, prices can range up to hundreds of thousands of pounds, he said. There is no better technology for the exacting demands of medical device manufacturing, however, where implanted metal or plastic devices must be prefect. Lasers can be focused to "drill" holes down to a few 10 millionths of a metre across.

Lasers are rated like light bulbs in watts, but there is little similarity in the light given off by these two items. A typical industrial laser would be rated from 15 to 400 watts, but the larger would produce a beam that can easily slice through one centimetrethick stainless steel. Lasers can be pulsed, Mr Flaherty said. This causes their actual power to peak, so a 400 watt pulsed laser actually produces a beam which at the target is rated in kilowatts.

A current research project at the centre is to develop ways to automate the monitoring of laser weld quality. The current method involves cutting cross-sections of the weld and testing the product to destruction, but this is often "after the fact", at the end of a production run after sub-standard product had been produced.

"More and more industry is trying to get to on-line monitoring so that it would not be necessary to scrap a whole production run," Mr Flaherty said. The power from a laser produces a plasma, a bubble of super-hot gas, where it contacts a surface and this plasma gives off its own light. The centre's approach is to analyse the light given off by the plasma as a way to interpret what is happening at the product's surface and to anticipate the quality of a weld.

The group is trying to correlate the signal received from the plasma with the weld quality and if it works, this data could in turn be fed back to the computer controlling the laser. "Ideally the output could be directed back to the welding laser which could then make an immediate change" and so improve weld quality, he said.

dahlstrom@irish-times.ie