Comfortably electric on the go Lasers boost car heater manufacturing

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FAULHABER Drive Systems

Webasto manufactures and distributes components for the automotive industry at over 50 locations worldwide. At the German Neubrandenburg site, everything revolves around heating – including for electric vehicles.

Heating through a heater in electric cars only works via a heat exchanger, which not only keeps the passenger compartment comfortably warm, as it is said. The battery also remains at a constant ideal operating temperature through it. As with all other components, the smaller and lighter the heater, the more ideal it is. Therefore, Webasto has developed its high-voltage heater, which, thanks to its thin-film technology, is emphasized to be the slimmest heater on the market.

Due to its close proximity to the coolant-carrying components, Webasto has an extremely short response time to transfer heat into the water. The special structure also allows the heating power to be regulated almost continuously, which works with both 400 volts and 800 volts of voltage. No one has managed to do this before Webasto. For production, the automotive supplier also relies on three high-end laser applications from Trumpf.

Webasto had to overcome three challenges:

• Gas-tight welding! The heater for electric cars circulates liquid through heating lines. However, liquid and high voltage in electric cars do not mix well. Therefore, the aluminum housing must be welded to be absolutely gas-tight. But welding aluminum sufficiently tight is not trivial. Electron beam welding in a vacuum is too slow and too expensive for mass production of electric cars. And laser welding often leads to gas inclusions that affect the tightness.

• Copper must be contacted precisely! To ensure that the current in the heater flows with low resistance, copper is needed. And of course, it needs to be contacted by welding. However, copper is reflective, so it is not an easy joining partner for the laser. And welds that are too deep jeopardize the layers underneath. Therefore, the welding depth of the laser must be precisely controllable. With the classic infrared laser, there's no point even starting;

• 3. Precisely structure the conductor paths! To keep the heater as slim as possible, Webasto wants to integrate the conductors directly into the thin metal layer on the surface, rather than applying them separately. In the structuring process, they also aim to achieve clean removal and precise edges. There must be no melting of the material to ensure quality.

The Trumpf answers to the three questions regarding challenges:

• 1. Gas-tight welding: Webasto relies on a fast and powerful Trumpf disc laser that works under atmospheric pressure without protective gas. The high laser power ensures a stable keyhole. Here the principle applies that a lot also helps a lot. Gas bubbles do not even have time to form;

• Copper must be contacted precisely: The green laser light from the Trudisk Pulse 421 has a high absorption rate for copper. With the right pulse sequence, welding depths can be achieved with extremely repeatable precision, which also works without splatter and completely without shielding gas. This has already worked flawlessly for several million components. Therefore, the green laser has become indispensable;

• Conductor paths must be precisely structured: Webasto uses a Trumicro ultrashort pulse laser to directly structure the conductor paths into the metal. This involves the highest precision in structuring the material so that the laser does not work too deeply and penetrate into the layers underneath. The ultrashort pulse laser sublimates the material. It immediately transitions from the solid state to the gaseous state. This creates the desired flat product design.

Triple-Power Implementation and Outlook for the Future

For Webasto, it is important that new developments reach market maturity as quickly as possible. That's why the company is very pleased that Trumpf's lasers could be directly tested. This also includes the good partnership with research institutes. In this way, Webasto can constantly maintain its products and production at the necessary high level. Therefore, in many cases, simply Trumpf lasers are brought into the production hall. For a company like Webasto, which produces in a high-wage country like Germany, a high degree of automation with the most economical production means, such as lasers, is necessary - as well as a high degree of innovation, which is evident, for example, in the introduction of new laser processes. This makes Webasto a sought-after player worldwide.