AUTOMOTIVE Trumpf e-mobility sales double in 2018


Trumpf laser technology for welding hairpins in electric motors


Laser welding of a battery tray for electric vehicles in the laser laboratory of Trumpf


Sales of lasers for electromobility from system supplier Trumpf have doubled in 2018 compared to 2017, according to the company. ‘Twenty per cent of our order intake from the auto industry is now coming from e-mobility – that’s twice as much as last year,’ Christian Schmitz, head of the laser technology division at Trumpf, commented during an Automotive Photonics technology conference organised at its Ditzingen, Germany, head office on 14 February.


‘The transition toward e-mobility


offers some major opportunities for industry,’ Schmitz said. Lasers have a key role to play in


battery production. The batteries consist of multiple layers of copper and aluminium foils that are cut to size using lasers. After adding liquid electrolyte, the battery is welded shut with a cap. A lot of the welding, including joining the copper foils, is carried out using a laser. Trumpf’s laser systems feature


acid graining and laser graining. For example, laser graining an entire dashboard would require between four to seven weeks, about the same time as acid graining, according to Reichle. ‘But with a lot of jobs, lasers are faster than using traditional acid graining,’ he added. Te main advantage, besides the short lead


time is the reproducibility of the process. Tere is no variance between one tool and another. Moulds for dashboards and the b-pillar around the door are normally both grained with the same pattern at 80µm, and there won’t be any difference between the two moulds when they are laser grained. With traditional manual graining methods, however, there is inevitably going to be some variability in the graining depth and gloss level. ‘We’ve developed our special low gloss and


ultra-low gloss concept, which means we can achieve any gloss level in any plastic material,’ Reichle said. Traditional etching methods are not able to achieve low gloss levels of 2.0 or 3.0 gloss units when working with PC-ABS or PC plastics, but a laser can achieve a gloss level of 0.5 for head-up displays, for example. Te laser graining method is not going to


replace acid grain completely, Reichle said, and the production time gains depend a lot on size of the surface area. When an injection tool is


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Laser machining injection moulds is taking over from chemical etching


put in an acid bath, the grain is applied over the entire surface, whereas a laser machine running time will double when the surface area doubles. ‘Graining over large surfaces is quite difficult to achieve the same price level as acid graining,’ Reichle said, adding ‘but you get a better quality.’ Te price depends on the grain pattern and the shape of the surface. Producing deeper


sensors that help control the welding process. ‘One problem for battery manufacturers is that they can’t test whether a battery actually works until the very end of the manufacturing process. They need the process to be monitored continuously to ensure that the battery comes out the other end working properly,’ said Schmitz. In addition, a series of laser


techniques have been shown to weld all the seams on an electric motor in just


one minute. Instead of winding thick copper wire around the coils of electric motors, a technique called the hairpin method uses a compressed-air pistol to fire a rectangular copper wire, similar to a hairpin, into a slot on the side of the motor. The protruding parts of the wire are then twisted together and welded using a laser. Trumpf has now sold more than 500


lasers worldwide for use in battery manufacturing.


grains of around 200 to 300µm will cost more using a laser than traditional etching, but a traditional fine grain or leather grain would be around the same cost, whether it’s laser machined or etched with chemicals. However, when a graining surface is directly next to a high gloss surface – in a headlamp bezel for example – then the cost will be much lower using a laser than with chemical etching, because the high-gloss surface doesn’t need to be protected in the laser machine, as it does in a chemical bath. ‘For surfaces in car dashboards, door trims


and exterior bumpers, the graining market is moving from traditional leather and fine grain to geometrical grains,’ explained Reichle. Geometrical patterns tend to incorporate a gradient in the grain. A more traditional bezel or door trim will have one grain from the leſt to the right side, but now new designs will start with a grain depth of 10µm and very glossy on the leſt of the part, and then the gloss level will change, moving to the right of the bezel and the pattern becomes more 3D. ‘In these new designs, it is only possible to do it by laser graining,’ Reichle said, ‘and that’s the reason why the laser business is growing. We started in 2012 and we’ve doubled our laser graining department every year.’


ISSUE 42 • SPRING 2019 LASER SYSTEMS EUROPE 13


Reichle Technologiezentrum


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