Automated optical adhesion testing of a two-component bonded automotive spoiler.
- TENTA VISION
- Jul 7
- 2 min read
Updated: Jul 8
Joint presentation with automation partner RAMPF Production Systems at the Bremen Bonding Days
Plastic components such as spoilers are an essential part of many vehicle concepts. The quality of the bonded joints is relevant to safety and can only be checked with great effort.
Together with RAMPF Production Systems, an automated optical solution was developed to test the adhesion between the two joining partners. It is possible to see where the adhesive is holding - and where it is not.
The cobot-guided sensor head is shown inspecting the relevant bonded surface of a plastic spoiler in three 400 mm x 300 mm scans. The spoiler consists of two parts: a painted, surface-mounted shell and an unpainted shell. Each part is approximately 4 mm thick and connected by 2K adhesive beads. During each scan, the sensor briefly observes the nano-deformation of the spoiler while its surface is heated by approximately 2 K via optical excitation. This design and procedure correspond to the end-of-line (EOL) testing concept currently in place. Instead, the in-line application uses a robot-guided component and a simultaneous three-sensor shot, with a test cycle time.
You can download the complete joint presentation by RAMPF and TENTA from Bremer Klebtage 2025, organized by Fraunhofer IFAM and ISGATEC, below.
The heating stresses the entire component because the warmer shell wants to expand but is prevented from doing so by the connected cold shell. This results in nano-bulging of the spoiler, particularly bending around its longitudinal axis.
The warm shell pulls on the adhesive beads. Where the adhesion between the two surfaces is reduced, for example due to oil contamination, the warm shell can expand more. TENTA's high-resolution sensitivity means an adhesive defect can be detected at 1 micrometer of anomalous elongation.
Since the software evaluation focuses on relative deformation excesses, the overall behavior of the test part is irrelevant. Therefore, geometric, material-specific, and structural conditions are almost irrelevant in this type of adhesion test.
After the images are processed in real time, deformation anomalies are displayed immediately, and adhesive defects can be identified. Photo analysis makes it possible to localize and quantify defects laterally (e.g., in cm²) and record adhesion percentages (e.g., 85% intact and 15% defective). Initially, the reduction in adhesion due to different types of defects is differentiated in two colors (red: no adhesion; yellow: reduced adhesion). Further studies will test an exact quantification.
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