Boy, there’s a lot to inspection! In-line versus off-line, rewind versus press-mounted, the human eye versus video—these are only a few, but critical, considerations. There are various inspection systems on the market, some for use on the press, and some for use on the rewinder as the web is rewound. Each inspection system is designed to take certain actions when it detects a defect in the printed product. These defects can range from registration to incorrect characters. In addition, with brand protection emerging as a growing market niche, the ability to inspect microprinting and other security markings not visible to the naked eye is becoming even more critical to the success of a print run.
No matter what type of inspection you employ, when a fault is detected, action is taken. Alfonse Novelli, owner, Novation, notes three possible actions:
1. The web can be automatically marked or flagged by a piece of equipment for removal of the defect at a downstream process;
2. The inspection rewinder, if running slowly enough, can be stopped at the location of the defect for removal and splicing at that time; and
3. The inspection rewinder, if running too fast to be stopped at the location of the defect, can be reversed to the location of the defect for removal and splicing at that time.
Tim Lydell, Label Vision Systems cites four actions the inspection rewinder can take when an error is detected:
1. Display the error on a monitor/notification light so the operator knows a problem was detected;
2. Activate a flagging or marking device so the error is marked for extraction in subsequent operations;
3. If it is on a printer, stop the print line and make the correction to the defective area; and
4. If it is on a rewind inspection device, it can stop the rewinder and reposition the defect at the cut table so it can be corrected as needed.