ADVERTISEMENT
You will be redirected to your destination in 15 seconds.
You will be redirected to your destination in 15 seconds.
The case of the unstable label
December 7, 2012
“My labels are wandering,” said Kelley.
“Well, that’s no good; they need to stay at home where you can keep an eye on them,” I quipped.
Kelley didn’t appreciate the humor but asked me to come take a look.
The labeler detected the gap between labels with a photo eye to position the label at the edge of the peeler plate. This label was transparent, and the eye was set to detect a label graphic instead.
Sometimes the label feed would stop short. Other times it ran over. Labels must always stop with the edge of the peeler plate in the middle of the gap to avoid application problems.
“Fiddlesticks on wandering labels, ” I roared. “You are triggering off of a circular graphic. It is opaque enough to give a good signal, so no problem there. If the label moves sideways even a little bit, the edge of the graphic, relative to the leading edge of the label changes. That’s what’s giving you an inconsistent stop position.
“You need to do two things to fix this problem,” I continued. “First, you need to go through the labeler fixing any loose or non-perpendicular guide rollers. This will stop your web from wandering side to side. Then you need the proper sensor. Get rid of the photo eye; it was never meant to work with a transparent label. A capacitance sensor will sense the edge of the label and stop precisely every time.”
What you see is what you get. If you can’t see the label, you can’t control it.
.
Posted by KC Boxbottom on December 7, 2012 |
Comments (3)
December 19, 2012
In response to:
The case of the unstable labelDusting Clays commented:
Really the best way to do it is with using an ultrasonic, capacitance or other sensor that detects changes in thickness like KC suggested. They're easy to train and will work for any label, be it a clear or white material and on a paper or PET liner. It is more cost up front but it a lot less hassle down the road.
Using eyemarks on the back of the liner adds another print station or they're added offline adding another process to manufacturing the labels. If it is a PET liner you may also need to use a printable liner, which adds additional cost as well.
Adding holes to the liner may work, but you weaken the structural integrity to the liner, which may lead to breakage, especially if you don't have good tension control on the labeling equipment. I've seen liners tear from just having a small nick in the web... Nobody wants more down time due to liner tearing.
December 12, 2012
In response to:
The case of the unstable labelKC Boxbottom commented:
That is one way to do it. I have also seen holes or slots punched in the web or ven through web and label.
Hoever I did have a case where the client did a black mark on a clear plastic web. It was not opaque and setting up the sensor to detect it and not the label graphics was touchy.
John Henry (A/K/A KC Boxbottom)
December 7, 2012
In response to:
The case of the unstable labelCoffee Queen commented:
We solved this by having our transparent labels cut on stock with timing marks on the back. End of wandering print.
Advertisement
Advertisement
