The case of the falling labels

He was sitting in my office when I got back. He was the packaging manager at a medical device company and had a labeling problem.

The labels dispensed onto a rubber pad and were held by vacuum. When the carton was in position, an air cylinder would lower the pad and tamp the label onto the carton. Most of the time this worked well. Occasionally the label would wander.

We went to his plant and I began by checking the labeling head from stem to stern. I found nothing abnormal or maladjusted.

When labels are misplaced, it is as often the product the product that is out of position. So I checked the carton positioning. All correct.

Some time spent in close observation of the system in operation finally revealed the problem. As the air cylinder lowered the tamp pad, the label would fall off. It did not fall far and much of the time gravity would get it to the right place but not always.

“I hate to be negative but that label is not being positively placed.” I told them. “It has to be held to the pad all the way down but the vacuum is releasing it before it makes contact.”

“Here’s your problem. Someone shortened the vacuum hose. Retracted, it works fine. As the applicator reaches the end of its stroke the hose gets pinched. This releases the label. Put a new, longer hose and your problems will disappear.”

Case closed.