| Roding, Germany
Fully-automatic packaging stations at the end of the production line are the future of aerosol can manufacturing; this means packers will no longer be there to have an attentive eye on the quality of the finished can. At the same time such a final inspection has become increasingly important since monobloc aerosol cans are more than simple containers today – they can be real design objects. Such a manufacturing process with its multiple shaping operations inevitably leads to high material strain. Additional to that, the wall thickness of aerosol cans progressively becomes thinner and the use of recycled aluminum surely protects the environment and preserves our resources but can be problematic when being processed.
At modern manufacturing sites inspection systems are already integrated into the aerosol can production at several crucial positions, typically prior to the printing process, after the printing process, and after shaping, necking, and flanging. These inspections are valuable measures mainly to prevent flawed products from being further processed and delivered to the final customer. Still this method cannot provide the conclusive assurance that every can is absolutely flawless. Defects can develop even at the very last moment and, as experience shows, time and again they really do. So the desire for a final inspection of the finished can is quite understandable.
The new final can inspection solution CIM, which is a cooperation of the two German companies Mühlbauer and Sprimag, covers all quality aspects of the finished can. At line speed the high performance can handler lifts the cans from the output conveyor of the necking machine, fixes them with vacuum, sets them in a stable rotation, delivers them to the inspection units and places them on a conveyor again for packaging. Three TEMA Vision inspection units are integrated: PI-CYLINDER for print inspection, CTI for can top inspection, which includes special optics for top, side, and backside view of the curl, and the brand-new 3D measurement SHAPE CONTROL. The inspection of the can shape is a special challenge. Although typical surface defects like grooves or dents cast revealing shadows in a 2D camera shot these optical effects can easily become invisible in the print image of a decorated can. The only chance to reliably spot such defects on a completely decorated and shaped can is the 3D measurement of the whole lateral surface – a height profile of the can. In contrast to PI-CYLINDER and CTI, which are already well known to aerosol can producers, the new SHAPE CONTROL creates a 3D image by constantly scanning a laser line on the rotating can.
The fully automatic 3-dimensional inspection of monobloc aerosol cans at the end of the production process is an inspection approach which combines newest technologies from 3D measurement, can handling, and inspection software. The end-of-line inspection solution CIM can be integrated into all aerosol can making lines successive to the necking process and is an important step towards a fully automated final inspection for aerosol cans which must be the declared goal for all modern aerosol can production sites in the near future.
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