Detection of pinholes during processing of aluminium materials

20.03.2020 Together, the German/Austrian companies Mendel RG-Systems and G. Rauch Präzisionswerkzeugbau GmbH, which has made a name for itself as a manufacturer of foil punching technology, are offering customers a new solution for detecting tiny holes in the material known as pinholes.

The SMARTSCAN inspection system for pinhole detection in aluminum webs.
© Photo: Erhardt+Leimer
The SMARTSCAN inspection system for pinhole detection in aluminum webs.

To do this, the SMARTSCAN 200% inspection system from Erhardt+Leimer (Stadtbergen, Germany) has been further developed in collaboration with Mendel RG-Systems so that, in addition to printing defects, it can now also detect holes up to a size of 20µm in the material. This type of hole detection is particularly important in the processing of closures and sealing devices in the food and beverage sector, where it acts as a quality criterion for ensuring that end products do not have any leaks.

200% inspection method

What makes the SMARTSCAN system so unique is its 200% inspection method. Thanks to a special illumination process using a combination of conventional incident light inspection and backlighting, with double image captures of the material under different lighting conditions, new standards have been set for quality assurance. This allows the SMARTSCAN camera to detect printing defects across the full width of the web using the incident light method. In addition, splices, flags, impurities/contamination and colour defects can be detected. After a short delay a further image is then taken for which only the rear flash is switched on.

By switching off the incident light, the material web is shown entirely in black. By contrast, holes up to a size of 20 µm are reliably displayed thanks to the flash of light from the rear. In addition, the holes are separately classified and can be displayed separately. To do this, the operator switches between print image and pinhole inspection on the multi-touch monitor.

Two separate systems in a single unit

SMARTSCAN is available for web widths up to 22 inches (560mm), with a maximum web speed of 300m/min. "In the past, the standard approach was to use two separate camera systems for print inspection and surface inspection, or to carry out inspections solely via the restricted 100% inspection," explains Alexander Thomalla, product manager at Erhardt+Leimer. "It is only the double imaging technique that enables the so-called 200% inspection, which combines two separate systems in a single unit."

Mendel RG-Systems will exhibit the SMARTSCAN system for pinhole detection at Drupa 2021.