In its plant in Waiblingen, Germany, Bosch produces plastic moulded connectors for the automotive sector. Plastic injection moulding is traditionally a difficult application for standard machine vision because of the lack of contrast between the background and the part being inspected – the “black-on-black” nemesis. To solve this problem, Bosch turned to Inspekto, founder of the Autonomous Machine Vision (AMV) category.
The automotive industry’s quality standards place high demands on production. Global competition and market expectations put growing pressures on automotive vendors to enhance their QA procedures, moving away from manual to automated inspection. The challenge is to find and implement cutting-edge machine vision methods.
The challenge: The problem with injection moulding
“Plastic injection moulding poses a lot of problems for traditional machine vision systems,” explains Zohar Kantor, VP of Sales & Project Management at Inspekto. “The highly reflective surface of plastic is hard to illuminate correctly. In addition, if the background material, the mould and the plastic polymer are a similar colour, and the available illumination is anything but ideal, a lack of contrast can make it very difficult for the machine vision system to work.
“Combine this with the fact that traditional systems can only inspect one type of product at a time — and manufacturers need to create product lines in different colours and sizes — it’s easy to see why a fundamental change in machine vision is needed.”
This was the problem Bosch was facing. In Waiblingen, the company produces plastic moulded connectors for vehicles, specialising in motor plugs, device connectors and sensor connectors. The plant has various production lines and injection moulding machines.
“The plant uses conventional state-of-the-art machine vision solutions, some developed internally, some created and integrated by external machine vision experts,” explains one of the development engineers for optical inspection systems at Bosch in Waiblingen.
“However, these solutions are not suitable for some of our applications, where the item that we need to inspect consists of a black polymer on a black background. In these conditions, it is virtually impossible to set the parameters for the QA solution to recognise defects.”
The plant had to check the connectors manually. As this is a tedious, repetitive job, inspectors might easily become tired and unfocused and fail to recognise defects. Moreover, the cost for personnel is significant.
After learning about AMV in an industrial report, Bosch approached Inspekto to see if the company could provide a solution to Bosch’s machine vision challenges.
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