April 2020

MACHINE VISION n Keeping a beady eye on adhesive bonds B onding is a key technology in automotive production and is used as a safe, economic alternative to welding, screwing or riveting. A typical modern car passes through dozens of gluing systems during production, and contains around 15–18kg of adhesive. In crash tests, vehicles with a high adhesive content usually performwell because the bonded parts are not negatively affected by the bonding process. Glue creates bonds without causing changes to materials – a real safety factor. Welding, on the other hand, generates heat, which can affect the materials used and their properties. And screws need holes. However, for bonding and sealing to achieve strong connections and to perform as required, the adhesive beads need to be applied precisely, especially for safety-relevant parts. They must be dispensed at all points to the same quality – even in corners and curves. A French company, Akeoplus, has developed a sensing system that checks adhesive beads in real time on production lines to ensure the quality of the material deposition. The company’s AkeoBI system inspects all types of beads on assembly lines – whether they are glue, mastic, silicone or foam. The system is designed to be bolted onto adhesive guns or onto the robotic arms that are used to apply the bonding materials. Algorithms check the width, continuity and position of the beads and detect any surplus or lack of material, with an accuracy of ±0.5 mm. This happens at speeds of up to 450mm/s. The sensing system is based on three high- resolution industrial cameras which provide a 360-degree panoramic view of the components being inspected. Illumination is provided by LEDs built into the sensors. Software analyses the camera images to detect defective material applications on the basis of previously stored criteria The results are shown on a user interface, and a report on every part being checked is available immediately after each inspection. This allows operators to locate and correct faults rapidly, without interrupting production, thus avoiding unnecessary downtime, ensuring traceability, and increasing production reliability. More than 100 of the AkeoBI sensing systems are already in use worldwide, including at the French automobile manufacturer, Groupe PSA, which owns the Citroën, Opel and Peugeot brands. The system is based on compact GigE uEye LE board-level cameras, supplied by IDS (Imaging Development Systems), which incorporate 1.3-megapixel CMOS sensors from e2v. As well as having good light sensitivity, the plug-and-play cameras offer two global and rolling shutter variants that can be switched during operation, thus adapting to changing requirements and environmental conditions. They support up to four AOIs (areas of interest), allowing several characteristics to be checked simultaneously. Alternatively, the AOIs can be captured in a series of exposures with different parameters. According to Akeoplus developer, Thibaud Cheippe, the cameras’efficient programming interface allowed the company to configure them accurately and easily.“Indeed, we were able to test and define precisely pixel formats, image size, frequency and all necessary features in advance,”he explains.“The images are then processed by the camera software. Start, stop and frequency of acquisition are precisely controlled.” Akeoplus believes that the combination of high-resolution cameras, high-performance LEDs and sophisticated algorithms could also be used by manufacturers in other sectors to improve the quality of their adhesive bonds and thus their products. n A French automation specialist has come up with a technology that uses three industrial cameras to inspect automotive bonding processes in real time as the materials are being applied, thus allowing any faults to be located and corrected rapidly, without interrupting production. The adhesive application inspection system is designed to be mounted on adhesive guns or robot arms to monitor the application of adhesive beads in real time.