For Gruber & Kaja, a supplier of engine-related aluminum die-cast parts to the automotive industry, the delivery of void-free components is a key success factor. This is particularly crucial for flat CNC-machined sealing surfaces in order to ensure that the sealing lip is fully seated. As part of the automation expansion of the production processes, the company invested in the previously manual visual blowhole inspection. The task: to reliably detect blowholes as small as 0.4 millimetres in a component size of 350 by 400 millimetres. Autoforce Vision Systems was the only supplier able to meet the requirements.

"Neither we nor Gruber & Kaja were aware of any system on the market that could automatically detect or evaluate such small blowholes for the given component size," explains Stefan Perg, one of the managing directors at Autoforce Vision Systems. In addition, the minimum roughness of the components in the specified active and passive sealing areas was a complex requirement. The machining marks on the surfaces, such as milling grooves, also had to be taken into account for the image acquisition. The solution from Autoforce Vision Systems: a multi-camera system with a specially designed dome-shaped illumination area. "By splitting the image across several cameras, we minimized distortion and increased the optical resolution. And thanks to the illumination dome, we achieved optimum illumination in order to filter out the milling grooves caused by the machining process and thus literally make them invisible," says Perg, explaining the central system structure. There is a slight overpressure in the lighting dome to prevent the ingress of dirt.

Autoforce Vision Systems uses six GigE cameras from Baumer's LX series with a resolution of eight megapixels to capture images. Image evaluation is carried out via Halcon thanks to the cameras' third-party compatibility. For this purpose, Autoforce Vision Systems programmed an application with which the individual images captured are merged with pixel accuracy to form an overall image and then overlaid with the original CAD data of the component currently being inspected to define the inspection regions.

The whole process only takes a few seconds. During the evaluation, the clamping frame with the component rotates 180 degrees to check the opposite side of the workpiece. An important criterion when selecting the cameras for the system was the ratio between resolution and pixel size. "We were looking for a camera with a robust design in which the chip size and therefore the size of the individual pixels would not be too small despite the high optical resolution," explains Perg. Equipped with the CMV8000 global shutter sensor from ams, the LXG-80 cameras from Baumer with a pixel size of 5.5 x 5.5 micrometers and a resolution of 3,360 x 2,496 pixels were the ideal choice. as