Light metal corrosion protection for battery platform components

Battery platform components made of light metals for vehicles react sensitively to environmental influences. The complex shapes made of aluminum or magnesium, for example, must therefore be specially protected against corrosion and partially coated.

Corrosion protection for complex (hollow) shapes made of aluminum prepared ready for assembly with a partial coating: A whole range of process engineering challenges come together in the structural supports for new battery platforms from various vehicle manufacturers. With decades of expertise and innovative, individual solutions for series production, the surface specialists from the Benseler Group tackle these requirements with precision and reliability - soon to be fully automated.

Light metal corrosion protection against environmental influences

Light metals such as aluminum (Al) and magnesium alloys (Mg) - frequently used materials in electric vehicle construction due to their significantly lower weight - react sensitively to environmental influences. Their corrosion protection is therefore of great importance. Not least because it is a highly complex matter, as Al and Mg require different processing than steel, for example. As pioneers in light metal corrosion protection, the surface specialists at Benseler have known this for a long time. "In the case of the structural supports that are installed in the battery platforms of various electric vehicles, it is not only the special material that plays an important role in corrosion coating, but also their complexity and the requirements for subsequent assembly," says Uwe Büchle, Head of Sales at Benseler Beschichtungen GmbH & Co.

The structural beams consist of so-called welded assemblies, rectangular hollow bodies, around 750 mm long, 90 mm deep and 140 mm wide with internal profile elements, various holes and welded-on bolts. "Corrosion protection on the inner and outer surfaces of the structural beams is necessary to prevent contact corrosion when different elements are attached during subsequent assembly," says Uwe Büchle. However, the upper end of the structural beams, which has already been pickle-preserved by the customer, must remain uncoated "so that the weldability and therefore the assembly capability is retained for the final installation in the platform or vehicle". All in all, orders that require know-how and precision work. In this case, the experts at Benseler rely on cathodic dip coating (CDC).

Selective coating in KTL system

With the help of cathodic dip coating, the welded assembly at the Kornwestheim site is given corrosion protection that is tailored to its requirements in an almost black high-gloss finish. The aim is to achieve high-quality, permanently reliable protection that ensures the desired installability on the previously defined uncoated surfaces of the components. This selective coating is achieved by a special process sequence within the cathodic dip coating system, so that even the already applied pickling protection is not damaged in the paint-free areas. The cathodic dip coating is then baked at a temperature of 180 °C. The finished structural parts are then returned directly to TIER 1 for the next assembly step.

Fully automated processes for aluminum components

With the current start of series production of these e-vehicle components, Benseler is also starting to automate the processes. "It is planned that the selective cathodic dip coating of these aluminum components will be fully automated from the end of 2023," says Uwe Büchle: "A novelty, because such a system - including fully automatic optical inspection - is a special feature." Several robots are installed for this purpose, which load the dipping racks, remove the finished structural supports after the coating process, feed them to the automatic inspection and lift them into the load carriers. Of course, the latter only takes place if the components are "OK" and have passed through the fully automatic surface inspection of the integrated inspection station. "This automation will relieve the burden on our employees, as soon there will no longer be any need for people to pick up the heavy components, which are unwieldy due to their width," says Sales Manager Büchle, explaining the benefits. "We are also improving the quality of our work once again with this step: thanks to automated inspection, inspection slippage tends towards zero as, unlike the human eye, the inspection camera does not tire even after many hours." (OM-11/23)

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Benseler Holding GmbH & Co. KG
Zeppelinstraße 28
71706 Markgröningen (Germany)

About Benseler

Benseler is a service provider and partner for technically sophisticated solutions in the areas of coating, surface finishing, deburring and electrochemical metalworking of series parts. The Benseler Group, based in Markgröningen near Stuttgart, consists of two divisions: Coatings and Deburring.