Inverted blanks detected in-line

The risk of producing ‘inside-out’ three-piece tinplate cans, in which cans are lacquered on the wrong side because inverted blanks are used, can be eliminated by using a detector from sensor specialist Innosen.

If coated sheets or body blanks are put into welders upside down, the resulting cans will come out with their protective coating on the outside and not inside. This could result from the unintentional stacking of sheets upside down or by blank flipping at the exit of the slitter. Left undetected, this problem could eventually result in rusting and blown cans, with inevitable complaints from brand owners.

Innosen claims its inverted blank detectors are the first on the market to detect the presence of inverted blanks – even with clear lacquer. They are installed on the outfeed of the welder or after the side stripe repair.

The IS621 Inverted Blank Detector works at up to 1,200 blanks a minute. Meanwhile, the IS631 Inverted Blank Detector is capable of detecting the presence of clear lacquer, white coatings and gold varnishes.

The sensors are fully self-calibrating and self-adjusting, so no operator intervention is required. When problems are detected, a reject signal for cans or missing lacquer on cans is generated. When a lacquer changeover occurs, it is detected by the sensor, which automatically learns the characteristics of the new lacquer. The device’s ‘heartbeat signal’ feature guarantees that the sensor is always working and can be used as a sheet counter for process monitoring.

More information from Innosen, Romà Piera Arcal 8, 08330 Premià de Mar (Barcelona), Spain. Tel: 34 937 549 526. Website: