BMW Group Plant Leipzig has moved terahertz-based paint thickness measurement into series production for plastic exterior components, deploying a system that inspects parts non-destructively where the old process required cutting them apart. The plant calls it the first application of terahertz technology to measure paint layers on plastic components anywhere in the plastics segment, and the first BMW site to integrate the method into in-house production.
The system at the center of it is "Irys" built by technology partner das-Nano specifically for inline industrial inspection. Sensors mounted on two robots in the plant's existing end-of-line measurement cell position themselves automatically against each component and measure individual paint layers by analyzing the time-of-flight of reflected terahertz waves. Each measurement takes seconds and resolves layer thickness down to the micrometre level.
What this replaces is the part that engineers will care about. Until now, Leipzig checked paint thickness on plastic exterior parts manually during production using scalpels and microscopy, destroying the component in the process. That approach generated scrap and tended to surface deviations from specification only later in the line. The terahertz cell produces objective, reproducible results without touching the part, which cuts waste and material consumption and flags process drift earlier.
The Exterior Plastics team that runs the cell produces injection-molded bumpers, side sills, and spoilers, supplying not only Leipzig but the BMW Group plants in Dingolfing and Regensburg. "Terahertz measurement technology replaces complex manual inspection with a fully automated solution," said Christoph Theiselmann, Head of Exterior Plastics, Production at Plant Leipzig. The data the system generates is fully digital, which the plant intends to feed into AI-based analysis to spot deviations and tune process parameters over time.
The technology follows automated surface inspection that Leipzig introduced in 2024, part of a wider push toward a fully digital paint shop for plastic components. After piloting and ramp-up, the system now works with all component carrier skids and is being enabled for every color variant. BMW frames it as a candidate for rollout to other plants, with painted body shops and the supplier network named as the most likely next targets.
