Avoiding scrap Inline quality control for metal forming

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Detecting surface deviations directly inside a progressive die could help manufacturers reduce scrap and identify tool wear earlier. Fraunhofer IGD’s camera-based Inform-QC system inspects formed components at up to 400 strokes per minute without slowing production.

In high-speed stamping and forming processes, detecting quality deviations during production is crucial. If wear-related changes are only identified afterwards, defective components have already been produced. The Fraunhofer Institute for Computer Graphics Research IGD addresses this directly within the manufacturing process with its camera-based Inform-QC system. It analyses the surfaces of formed components inline and detects changes that may indicate tool wear.

Quality inspection at production speed

Inform-QC can, for example, be integrated into an available station within a progressive die, eliminating the need for an additional external inspection station.

The technology is based on photometric stereo: the component is illuminated and imaged from different directions. From these images, the system calculates a digital representation of the surface topography, which is compared with a reference. This allows fine deviations to be detected and linked to potential process stages or tool components.

Analysis runs continuously at production speeds of up to 400 strokes per minute, without slowing the production cycle. The underlying approach can also be applied to other stamping, deep-drawing and forming processes.

“At high production speeds, downstream quality control can come too late. Our aim is therefore to detect changes where they occur – directly in the forming process. The component surface not only tells us about the quality of the individual component, but can also provide indications of the tool’s condition,” says Hasan Kutlu, a researcher at Fraunhofer IGD.

Surface changes may, for example, indicate abrasion or material build-up on the tool (adhesion). Detecting these changes early allows companies to respond more quickly and reduce scrap. At the same time, the data collected provides a basis for condition-based maintenance and, in the longer term, predictive maintenance.

Further development for lubricated surfaces

Research to date has focused on dry metal surfaces. In industrial forming processes, however, metal strip is usually lubricated. The lubricant film changes the optical properties of the surface, placing additional demands on camera-based analysis.

In a newly launched follow-up project, Fraunhofer IGD is therefore investigating how the method can be applied to lubricated surfaces. The research examines how the influence of the lubricant film can be accounted for or specifically exploited during digitisation and quality analysis. The aim is to bring the technology more closely into line with the conditions found in industrial forming processes.

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