Bearer Bar Problems

Red_Right_Arm

Well-known member
We're running into an issue with bearer bar registration recently.

The issue reared up at the same time the laser etcher was acting up. Okay, so we got the laser serviced. The issue remained. We looked into how we are applying the plates to th
e vacuum drum, making sure not to lay the plate over any tape or masking film. We make sure the entire back of the plate is in contact with the metal drum before taping it down. The issue remained. I can't think of what else might be causing this issue, and other departments are positive it is coming from the plates, not human error with mounting.

Some coworkers, who have spent time at other companies, have stated that this is a common problem that is no big deal. However, department heads I work with aren't very likely to accept "Hey, it happens" as a response. So, I'm wondering if anyone else runs into this problem, and if so, how do they rectify it?

Here's a photo of the issue. When two plates are lined up front to front or back to back, the bearer bars are in registration. However, when the plates are lined up front to back, as they would be when wrapped around a cylinder, one of the bars are noticeably out of register. (Note: We use a dual camera mounting system that displays both sides at once. When mounted, the difference in registration is more apparent and there is a larger seam gap on the side that is out of alignment. Unfortunately, we can't use cell phones on the production floor, so I couldn't get that picture.)
 

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WI-Flexo

Well-known member
Does this happen if you line up new plates on a flat surface before mounting? One thing that can happen in mounting is if the mounter tends to "pull" one corner of the plate over the other causing the plate to skew. Especially shows up on large repeats. If the issues shows up before mounting then I am leaning towards the laser focus being the issue.
 

Red_Right_Arm

Well-known member
Does this happen if you line up new plates on a flat surface before mounting? One thing that can happen in mounting is if the mounter tends to "pull" one corner of the plate over the other causing the plate to skew. Especially shows up on large repeats. If the issues shows up before mounting then I am leaning towards the laser focus being the issue.

Indeed it does. This photo is from two plates that haven't been mounted yet. Also, it does seem to be more noticeable, as seen here, with wider plates. I would think that it's the laser too, but we just had it serviced. With a 25x loop the 1% dots look sharp and crisp. It doesn't seem to be related to the laser focus. Although I haven't yet ruled out the possibility that it may be coming from the laser in some other factor that is malfunctioning.
 

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