Laser welding process: green wavelength laser welding process saves electric vehicle manufacturing raw materials

TRUMPF Germany issued a press release on April 20, 2023: The collaborative study by TRUMPF, Fraunhofer ILT and DESY introduces the most detailed laser welding process to date, and thanks to particle accelerator/Fraunhofer expert Marc Hummel, researchers have clearly demonstrated for the first time that raw materials can be saved when welding high-performance electronics by using lasers with green wavelengths.

In the welding of high performance electronic products, a lot of raw materials can be saved. This is the result of a survey conducted at DESY, a large particle physics research institute in Helmholtz in Hamburg, Germany. Every electric vehicle is equipped with high-performance electronics as a key technology that ensures optimal performance of batteries and motors. Researchers in Hamburg, together with the high-tech company TRUMPF and the Fraunhofer Institute for Laser Technology ILT, are currently working on laser welding processes for building electric cars. TRUMPF, Fraunhofer ILT, DESY and Helmholtz centers each offer their high degree of expertise in X-ray, laser sources and welding processes. It was found that when green wavelength laser was used, the scrap rate was much lower than other laser welding processes. It can help the sustainability of manufacturing by enabling car manufacturers to save on raw materials.

Figure 1: "Green" laser beam welding of cermet substrate. Photo: FraunhoferILT

The project partners used bright X-rays from the Heron Experimental facility's particle accelerator for their research, taking high-speed images at a rate of several thousand to ten thousand frames per second. The researchers wanted to use the particle accelerator study to find out exactly what caused the difference in the copper welding process. A stable welding process is important because electric car makers must weld billions of connections of the highest quality, said Marc Hummel, a scientist at the Fraunhofer ILT. In the future, TRUMPF and Fraunhofer ILT plan to expand the research into other areas, such as 3D printing, laser cutting and ultra-short pulse laser drilling, and to include other industry partners in the research area.

Figure 2: Particle accelerator research. TRUMPF and lT Fraunhofer conducted laser welding research at a particle accelerator at DESY in Hamburg, Germany. Photo: TRUMPF

Green wavelength laser is used, and the rejection rate is lower

Electric cars pose a major challenge to laser technology. Copper is the most important material used to make the core components of electric cars. This non-ferrous metal absorbs only about 5% of laser radiation in the near infrared (NIR) range and conducts heat very well. Both of these properties can cause considerable problems when welding. In addition to near-infrared lasers, TRUMPF also has green wavelength lasers in its product line. Lasers with green wavelengths are a solution to this problem, says Mauritz Moller, an automotive industry manager at Trumpf. Using these lasers allows better welding of copper, which absorbs green wavelengths much better than infrared. Because the material reaches its melting temperature faster, the welding process also starts faster and requires less laser power. A more stable welding process means less scrap rate and thus greater sustainability, which is a major issue in electric vehicle manufacturing.

Figure 3: Laser welding process research. Trumpf and LT Fraunhofer studied laser welding of copper connectors in high-performance electronics in electric vehicles at a sub-accelerator of the German electron Synchrotron DESY in Hamburg. Photo: TRUMPF

Experiments in particle accelerators

In order to study the welding process in detail, experts from the Fraunhofer Institute of Industrial Technology, in collaboration with the Institute of Laser Technology at RWTH Aachen University, used DESY's PETRA III X-ray source on the experimental facility at the Helmholtz Center. Traditional methods actually only see the electromagnetic emission of plasma. With DESY's radiation, not only can the melting interior be seen, but we can even see the dynamics of the melting.

Figure 4: The collaboration between Trumpf and Fraunhofer. Trumpf and FraunhoferILT provide expertise in laser sources and welding processes for particle accelerator experiments. Photo: TRUMPF

In summary, the team from Fraunhofer ILT and TRUMPF studied DESY's laser welding process using two different laser systems (near infrared laser and green wavelength laser). It is a good opportunity for them to study the welding process of industrial parts. For example, how splatters and pores form, and how heat from the welding process affects sensitive parts such as electronic parts.

Source:

https://www.ilt.fraunhofer.de/en.html

https://www.trumpf.com/en_INT/