If engine‘s cooling fans fail, it can lead to the overheating of the power unit–and, in the worst case, to engine damage. That´s why an automotive components manufacturer inspects the quality of its fans. Since early 2024, machine vision systems have been ensuring reliable and cost-effective quality control at four testing stations in the company.

An automotive components manufacturer supplies many carmakers with its technologies. In the area of thermal management, this U.S.-based group also includes fans for large engines, such as those used in trucks, construction machinery, and other commercial vehicles. 

“The company aimed to increase the level of automation in its production process and ensure that only flawless fans would be delivered to customers for later installation in engines to avoid consequential costs in the event of a defect,” recalls Andreas Schaarschmidt, Managing Director of Vision On Line. “To implement the required vision systems, they were looking for an experienced partner. We had already successfully supported the company in previous projects, so we were very familiar with their processes.”

High precision required

The machine vision systems from Vision On Line have been integrated into the production process of the fans, in four stations where the components are balanced. After placing a test specimen, the integrated vision system first detects a metallic, black-painted metal part that contains a data matrix code with information about the specific fan model. Once the vision system has read this information from the centrally located metal part, it is communicated to the manufacturer’s internal PC-based control system to retrieve the target values for the fan under inspection.

In the next step, the vision system checks a number of characteristics of the components for compliance with the specifications. Among other things, it examines the correct number and geometric dimensions of the individual fan blades. For optimal performance of the finished fans, it is crucial that any overmolding or missing material be reliably detected with an accuracy of +/- 1 mm.

The measured data is then compared with the target values from the central control system, and if all specified parameters are met, the inspected fan can be statically balanced in the next steps and delivered to customers for later installation in engines. Faulty components are removed from the process and, depending on the type of defect, are either reworked or discarded.

A selected vision system

The task assigned to Vision On Line was extensive: on the one hand, the fan manufacturer had previously not used any system capable of automatically inspecting such fans. On the other hand, the components to be tested required a precisely tailored vision system configuration, as the fans demanded a relatively large field of view due to their diameters of up to 800 millimeters.

“The required precision could only be achieved by selecting a large brightfield illumination from Büchner and a high-resolution 20 MP camera from SVS-Vistek, combined with matching optics from OPT,” explains Schaarschmidt. According to him, image evaluation is performed using the Halcon software library from MVTec.

A key factor in the final vision system for this application was the illumination, for which Vision On Line selected a customized model from the TLS series by Büchner Lichtsysteme. These brightfield area lights operate with either direct or diffuse light, are available in blue, green, red, white, and infrared, and can accommodate multiple camera openings as needed. For this specific application, it was important that the dimensions of the illuminated area could be configured up to 2 x 3 meters in 20 mm increments. For the fan inspection, Büchner produced a TLS variant with an illuminated area of approximately 600 x 600 mm, fitted with a total of 3,500 blue LEDs and an electrical power output of 177 W. 

Based on his many years of experience with SVS-Vistek, Schaarschmidt trusted their cameras when making his selection: “We’ve integrated industrial cameras from this partner into our systems many times in the past. Since SVS-Vistek manufactures its cameras in-house at their facility in Gilching, Germany, we can also rely on timely delivery of the ordered units.” For the inspection of the American manufacturer’s fans, the Exo183MGE model is used. This camera is particularly well-suited to the application thanks to its high resolution of 20 megapixels and data transfer rate of up to 120 MB/s via the integrated GigE Vision interface. Another key advantage is the camera’s integrated 4-channel power strobe controller, which enables precise timing of the LED lighting. This eliminates the need for a separate external controller, helping to reduce the overall cost of the vision system.

Defect Detection

A challenge for Vision On Line was to integrate the vision system into the manufacturer’s internal PC-based control system, enabling seamless use and documentation of inspection results within the production environment.