Joined-up thinking

Change in automotive industry production methods happens slowly. With hundreds of millions of pounds invested in incumbent manufacturing techniques, it’s easy to see why.

But with the world’s car manufacturers increasingly keen to reduce the weight of their vehicles and to improve the efficiency of their manufacturing processes, a number of advanced manufacturing techniques are receiving increasing amounts of attention.

One technology with particular promise is remote laser welding (RLW), an emerging joining technique that many believe has potentially huge advantages over the spot welding technology that is widely used in the automotive industry.

Working with €4;4m (£3.3m) of EU funding, the UK-based Warwick Manufacturing Group (WMG) has joined forces with industry partners, including tier-one automotive supplier Stadco along with Jaguar Land Rover, to help usher this innovative welding technique into the manufacturing mainstream.

Prof Darek Ceglarek, who is heading up WMG’s RLW Navigator (Remote Laser Welding System Navigator for Eco Resilient Automotive Factories) project, explained the differences between resistance spot welding and its potential rival.

Resistance spot welding - which joins parts using the heat generated by resistance to the flow of electric current - is a contact technology. This means that access is required to both sides of the part to make a joint.

By contrast, RLW is a non-contact technology and only requires access to one side of the part - a single high-power laser beam is used to create the joint. By having laser optics embedded into the robot, and a scanning mirror head as the end effector, RLW can easily create joints in different locations of the product through simple robot repositioning and laser beam redirection from a remote distance. This means that, as long as there is a ’line of sight’ between the scanning mirror and the joint location on the assembly, creating a laser weld may be feasible.

Using this approach, RLW is able to create a joint in a fraction of a second, and Ceglarek estimates that the process is as much as five times faster than spot welding.

“As RLW is faster, one robot is available to carry out more work- reducing the amount of floor space required”

But the advantages don’t end there. Because it’s faster, one robot is able to carry out more work, and this means that floor space could be reduced by as much as 50 per cent.

The requirement for fewer robots could also have major implications for maintenance costs and energy usage. Ceglarek claimed that, overall, RLW could reduce assembly costs by 10 per cent.

The technology also has some less obvious but equally compelling design implications. A vehicle’s design typically takes into account the manufacturing techniques that will be used to produce it, and most cars contain a high number of flanges on the edges of parts joined using spot welding. With RLW, these flanges - which contribute around 200kg to a car’s weight - could potentially become redundant: a very attractive advantage for an increasingly weight-conscious industry.

So far, RLW has been limited to fairly niche applications of low-production-run components. This is largely because engineers have struggled to find a way of controlling the process with the degree of repeatability and accuracy required for high-volume production. Indeed, according to Ceglarek, most existing applications of RLW have relied heavily on trial and error to get the process right.

The big challenge, he said, is that effective laser welding requires the extremely close control of the gap between the parts to be joined - and the discrepancies between the tolerance of the parts to be joined can make it extremely difficult to maintain the optimum gap between the components.

The aim of the WMG project is to develop a simulation tool that will replace guesswork with precise mathematical modelling that will quickly deliver the efficiencies manufacturers want from this process. Ceglarek explained that the aim is to develop a system able to precisely model the process, configure the production systems and optimise the control of the welding.

There’s clearly a long way to go in the development of what Ceglarek describes as a high-risk project. But with Jaguar Land Rover reportedly keen to see the technology developed as quickly as possible, he hopes that it could be helping to reduce assembly times within the next few years.

In the longer term, with many of the fundamental challenges cracked, it is hoped that the technology could be deployed across a range of sectors.