Fraunhofer Institute for Industrial Mathematics ITWMTogether with the automotive supplier Antolin Straubing GmbH, we have developed a mobile terahertz measurement system that performs non-destructive testing of slush skins. The technology ensures that airbags function reliably in an emergency, reduces scrap, and supports more sustainable production.
Airbag Slush-Häute
© freepik / Fraunhofer ITWM
Terahertz Inspection of Slush Skins: Greater Safety in Automotive Production
Best Practice at the Antolin Straubing GmbH – Ensuring Airbags Provide Reliable Protection: Non-Destructive Testing of Slush Skins
Modern vehicle cockpits are designed to look high-end while also meeting the most stringent safety requirements. That is why so-called »slush skins« are used in many mid-range and luxury vehicles. These are leather-like plastic surfaces that cover dashboards and can be shaped flexibly.
The Antolin Straubing GmbH developed a new two-layer system for these components. It saves material and weight while improving adhesion to the cockpit carrier. However, to ensure that the new design does not impair the airbag’s function, a testing method for series production was needed. Together with the Antolin Straubing GmbH, we therefore developed a solution that quickly and non-destructively checks the critical material properties.
Terahertz Technology Measures Coating Thicknesses Without Contact
For many years, we have been researching the industrial application of terahertz technologies. For quality control of slush skins, we use terahertz waves to non-contact measure the thickness of individual material layers. To do this, we send short electromagnetic pulses into the component. These pulses are reflected at the interfaces between different layers. Based on the transit times of these signals and the material properties, we calculate the thickness of the individual layers.
The particular challenge was to reliably analyze the complex structure of the slush coats. Unlike conventional multilayer coatings, they do not have a uniform internal structure and contain small air pockets. Therefore, we developed special analysis algorithms that precisely determine the actual layer structure based on measurement data and reference signals.
Cross-section of a slush skin: For the airbag to deploy reliably, the predefined tear lines must extend right to the top layer.
Greater Safety Through Reliable Airbag Performance
The measurement focuses in particular on the area of the predetermined fracture point. There, the material thickness must fall precisely within defined limits so that the airbag can safely penetrate the trim in the event of a crash.
Using the developed method, we inspect each component non-destructively. This provides manufacturers with reliable quality control directly on the production line. In this way, we enhance the safety of vehicle occupants while simultaneously avoiding material loss caused by destructive testing. Furthermore, it reduces scrap, rework, and resource consumption. The technology thus combines safety requirements and sustainability in a single step.
Portable Terahertz Measurement System for Manufacturing
To ensure that testing can take place immediately after production, we have designed the measurement system as a mobile cart with a hand-held measuring head. A custom-developed human-machine interface, touchscreen, power supply, and barcode or QR code scanner enable easy operation directly on the production line.
For quality control, employees position the measuring head on predetermined measurement points on the slush skin. After a successful measurement, they receive immediate feedback and can read the measured layer thicknesses directly on the display.
Terahertz Measurement Technology for Additional Industrial Applications
The solution developed is not limited to slush skins. This technology offers great potential in any application where wall or layer thicknesses need to be measured non-destructively. Possible applications include, for example, plastic components in vehicle interiors, fiber-reinforced plastics, foams, or pipe walls.
The measuring head for the mobile terahertz system comes with a color display showing signal strength, operating mode and layer thickness results.