ANALYSIS & OPINION
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Adding up in Aachen

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Matthew Dale reports from the International Laser Technology Congress, AKL, where the potential for using additive manufacturing in series production was discussed

More than 650 users, manufacturers and developers of laser systems from 26 countries convened in Aachen at the beginning of May to discuss the current and future trends of industrial laser technology at the 12th International Laser Technology Congress, AKL.

Two themes were repeated throughout AKL: the increasing impact of additive manufacturing (AM) in industry as it becomes a more viable tool for series production; and the ramping up of ultrafast lasers to kilowatt average powers for large-scale ablation uses.

It was made clear at the conference that metal AM is making significant progress toward becoming a tool for series production, with BMW even demonstrating that, for the first time, it has incorporated a component optimised for selective laser melting (SLM) into a series-production vehicle.

As explained by Maximilian Meixlsperger, head of AM metal at BMW, the group’s i8 Roadster, which was on display at the conference, contains a metal bracket in its convertible top that can be additively manufactured in batches of 627 components. The bracket is designed to achieve maximum stiffness while using the least material possible, demonstrating 10 times the stiffness at 44 per cent less weight compared to a previously tested part made using injection moulding. According to Meixlsperger, the aluminium SLM process used to produce the bracket proved more cost-efficient than an alternative magnesium die-cast process when making the bracket in quantities of up to 60,000.

In addition to the bracket, BMW plans to additively manufacture a number of other components for its cars. However, in order to implement this effectively in series production, a number of factors must first be addressed, said Meixlsperger.

BMW's i8 Roadster is the first series-production vehicle to contain an additvely manufactured part. (Image: Fraunhofer ILT, Aachen/ Omer Seven)

‘We have massive demands in faster AM machines,’ he said. ‘The productivity of AM machines, especially the ratio against investment, needs to be optimised by a factor of 10 to 100. This will reduce the cost-per-part by a factor of 5 to 10.

‘We also need automated digital and hardware workflows,’ he said. ‘These machines need to achieve 24/7 automated production, we just have to make sure they have the materials that they need to operate.’

BMW has a need for reliable, failsafe AM machines that are dedicated to automotive production and have proven capability, as well as a need for open and standardised software/hardware interfaces.

Meixlsperger also said that the surface quality of additively manufactured parts would have to be improved before they can be produced in series.

BMW's i8 Roadster contains an additively manufactured bracket that is both stiffer and lighter than similar conventionally manufactured components. (Image: Fraunhofer ILT, Aachen/ Melanie Conrad-Franzen)

BMW has also identified issues in the current powder offerings available from suppliers: ‘We need material that’s more reproducible and a lot cheaper than what we see today,’ Meixlsperger said. ‘The cost of 1kg of powder is currently 10 times more than the cast part in the car, so we need a lot of optimisation there, in order to produce larger business cases.’

Powder needs to be certified to quality standards and the handling of the material needs to be improved, Meixlsperger added.

I see a bright future for AM in our industry, but it will take time until the machines are there that actually utilise the cost we need to really go into large scale production,’ concluded Meixlsperger. ‘There is a lot more to do than just AM machine optimisation, however. We have to train our developers, optimise the part and process chain, and standardise the whole production process within the automotive chain.’

In this example, BMW is using AM as a manufacturing tool, rather than a prototyping tool. Stéphane Abed, director of additive firm Poly-Shape, showed figures that demonstrate an increase in the percentage of the AM market dedicated to final part production, growing from 19.9 per cent in 2008 to 32.4 per cent in 2017.

BMW displayed its S1000 RR motorcycle with an additivley manufactured chassis at the conference. (Image: Fraunhofer ILT, Aachen/ Andreas Steindl)

Figures were also shown from a recent market study by Wohlers Associates that revealed an almost 80 per cent increase in the number of metal AM systems sold in 2017 compared to 2016, from 983 systems to 1,768. The same study found that 135 companies produced and sold industrial AM systems costing more than $5,000 in 2017, an increase from 97 companies in 2016.

Despite these increases, a number of challenges – in addition to those identified by BMW – still exist in AM today that could hinder its widespread adoption as a tool for production, particularly when producing large parts, according to Abed. These include: an inefficiency in commercial machines when using large volumes of data; residual stress that induces distortions in larger parts; a lack of standards and normalisation concerning powder management; more rigorous and consistent production quality control; and a more efficient way of removing the large quantities of residual powder from AM machines and completed parts post-build.

‘We need to work hand-in-hand with powder suppliers, software suppliers and machine providers, because we still face some difficulties, and to arrive at production-level rapidly we will have to work together to solve these problems,’ Abed concluded.

Digital production

The conference was used as an opportunity to launch the I3 Research Centre Digital Photonic Production (I3 -RCDPP) on the RWTH Aachen campus. This integrated interdisciplinary institute will host approximately 80 scientists from six university faculties – materials engineering, mechanical engineering, electrical engineering, natural sciences, business and economics, and medicine – to research how photons and their properties can be used in future production.

The building complements the Digital Photonic Production Industry Building, which was opened in 2016.

Professor Dr Reinhart Poprawe, director of Fraunhofer ILT, spoke at the launch event for the I3 Research Centre Digital Photonic Production. (Image: Fraunhofer ILT, Aachen/ Melanie Conrad-Franzen)

The idea is to connect all the wonderful instruments that we have for projects and collaborations: research groups, collaborative research clusters of excellence, the Fraunhofer projects and Fraunhofer centres of excellence, industrial research, prototype production and testing,’ commented Professor Dr Reinhart Poprawe, director of Fraunhofer ILT at the launch of the new I3 building.

While in previous years universities have produced innovations that later find use in market applications, with the new interdisciplinary research format, these innovations will be developed while simultaneously finding applications in new markets, according to Poprawe, both shortening development times and widening the solution space of new technology.

‘The more a subject becomes relevant to industry and society, the more it will demand fundamental research,’ he said.

AKL covered laser welding, cutting, additive manufacturing, process control, micro joining, polishing and thin film processing.

Conference attendees could see more than 100 live laser applications at Laser Technology Live. (Image Fraunhofer ILT, Aachen)

There were also presentations on beam sources such as solid-state lasers, fibre lasers, diode lasers and ultrafast lasers.

Attendees were given the chance to see some of these developments up close at Laser Technology Live, a set of 100 live presentations given at the Fraunhofer Institute for Laser Technology (ILT), where staff were on hand to discuss the ILT’s latest developments in depth.

Awarding innovation

A team made up of representatives from Laserline, Scansonic and Volkswagen won the Innovation Award for Laser Technology at AKL. The group was presented first prize for its multi-spot modules, which can produce tailored spot geometries to improve joining processes.

Presented by the European Laser Institute and Arbeitskreis Lasertechnik, the award recognises work that has led to an outstanding innovation in the field of laser technology, that centres on the use of laser light in materials processing, and that demonstrates commercial value to industry.

Dr Axel Luft, from Laserline, collected the €10,000 award. The winning system combines a Scansonic ALO3 tactile head together with an automated Laserline triple spot module to enable high quality brazing of hot-dip galvanised material in production lines.

A team made up of representatives from Laserline, Scansonic and Volkswagen won the Innovation Award for Laser Technology at AKL. (Image: Fraunhofer ILT, Aachen/ Andreas Steindl)

The system offers adjustable power distribution between three laser spots, and, as of this year, can now do this on the move using robotics. In addition, when welding aluminium, the system reduces spatter, increases welding speed and increases penetration depth, while also achieving a high-quality surface appearance.

The new system has applications in all sectors of laser beam joining where seam geometry and surface quality are in high demand, as well as in processes that tend to spatter. Example applications include the brazing of hot-dip galvanised sheets, aluminium welding in the outer skin of car bodies, and for welding tailored blanks, battery cases and gear wheels.

‘This very successful system has been commercialised with Volkswagen and is now the preferred solution for brazing hot dip galvanised steel, with more than 40 sets of these optics in current use,’ said Dr Paul Hilton – one of the jurors for the award and a technology fellow at TWI – at the award ceremony.

Second prize went to a team represented by Dr Gerald Jenke, from German firm Saueressig, for its ultrafast laser ablation tool. The technology combines a 500W picosecond laser with a programmable multi-beam processing head and related processing technology to enable ultrafast laser ablation in large-scale precision manufacturing.

The head is based on a multi-spot diffractive optical element with an efficiency of more than 90 per cent, in addition to a multi-channel acousto-optical modulation system, which 
enables individual beam switching and modulation with a data rate 
of 6MHz for each beam. The technology lowers manufacturing costs, reduces processing times and improves quality assurance for applications in automotive, micro-embossing, nanolithography and thin film ablation. For consumer products, this could mean new functionalities, such as reductions in friction, increased lifetime, improved soft touch, enhanced anti-bacterial effects and light diffraction being implemented in an economic way, even on larger parts.

The first, second and third place winners of the Innovation Award for Laser Technology. (Image: Fraunhofer ILT, Aachen/ Andreas Steindl)

Third prize went to a team represented by Alejandro Bárcena, from Talens Systems, for its RAIO DSS technology, a dynamic beam control system for laser heat treatment and related high-power laser applications.

The system gives custom beam delivery by means of a fast-oscillation two-axis scanner and controlling software. It can provide energy density patterns with a fully prescribed beam energy deposition distribution. This enables the homogeneous laser treatment of critical areas, such as corners or smaller mass zones with full control of the material evolution, as well as fully precise laser energy tailoring.

The technology offers reduced manufacturing costs for products with requirements of selective zone hardening, less geometrical distortion during heat treatment, as well as improved quality assurance via monitoring and control systems. It has applications in industries such as transport, precision tools, heavy industrial equipment, energy generation, mould and stamping, and biomedicine.

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