Brazing the stakes

Laser brazing, a joining technology rapidly gaining popularity in car manufacturing, has received a boost with the news that Corus is setting up an R&D facility to study the technique.

Laser brazing, a joining technology rapidly gaining popularity in car manufacture has received a boost with the news that Corus is setting up an R&D facility to study the technique.

Brazing, which involves melting a ‘filler’ material between two parts to form a joint, has long been used alongside traditional welding techniques. It helps reduce the risk of the heat source adversely affecting the properties of the parent materials.

The use of a laser to melt the weld filler makes the technique even more precise. The temperature required can be easily controlled and the heat source can be accurately directed on to the filler material, further protecting the parent materials.

Corus anticipates that there will be a growing trend by vehicle manufacturers globally to adopt laser brazing and welding, with German car makers in particular pushing hard for these joining technologies.

Dr Peter Jongenburger, chief technology officer at Corus said laser brazing produces a stronger join than a traditional seam of resistance spot weld, leading to a stiffer body structure.

This, he said, results in ‘improved passenger safety and ibetter vehicle handling.’Indeed, according to Paul Hilton, an expert in lasers at TWI (formerly known as The Welding Institute) the advantages of laser brazing have already been recognised by vehicle manufacturers.

Hilton explained that while the earliest reference he could find to laser brazing was in 1977, the first modern use of the technique in the automotive industry is on the Audi TT. Here an external joint on the car’s body is laser brazed.

The R&D centre, which is to be situated in IJmuiden in the Netherlands, will allow Corus to determine the performance of materials during laser welding and brazing, enabling the company to improve material properties.

For example, Corus will be able to research the effect of different pre-treatments and coatings, improve joining of components such as hydroformed tubes and make prototype tailor-welded blank components in steel or aluminium for automotive customer evaluation.

Roger Hammond of Corus explained that the purpose of the centre is to establish exactly where the technique should and should not be used.

‘There are many trade-offs,’ said Hammond.’ Just some of the variables that come into play are workpiece distortion, joint geometry, material type, material thickness, microstructural properties, running costs, investment costs and gap tolerance. When a new technology comes on the scene, the idea is to try and balance all the variables and try to find the best application.’

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