FLEXO Printing Issue on MARK ANDY: Persistent LINE Across Web on All Colors

[Sdbruyne]

We are experiencing a recurring issue on our Mark Andy P7 flexo press and I would like to hear if anyone has seen something similar.
A thin line consistently appears in our print, always in the exact same position across the web. The problem is visible on every color station, so it doesn’t seem to be related to just one anilox, plate, or ink.
We have checked cylinders, plates, and inks, but the line keeps showing up in the same spot. It’s not random; it is always repeating in the same location, regardless of the job.
Has anyone dealt with this before? Could it be related to a mechanical issue (roll, impression, or web path) or possibly something in the press configuration?
Any advice or experiences would be greatly appreciated.

 

[Cornishpastythighs]

If the lines appear to go across the web direction which might indicate too much anilox pressure to plate or plate pressure to substrate (impression) can sometimes result in a 'bounce' at a non print area on the plate. Narrow web label printers typically control this problem by adding "bearer-bars" to the outside edges of the plate. just a suggestion

 

[Sdbruyne]

If the lines appear to go across the web direction which might indicate too much anilox pressure to plate or plate pressure to substrate (impression) can sometimes result in a 'bounce' at a non print area on the plate. Narrow web label printers typically control this problem by adding "bearer-bars" to the outside edges of the plate. just a suggestion

Thanks for the suggestion. In our step-and-repeat we already include bearer bars on the outer edges, and we also run an ink eater (currently set at 10% on each color). What makes this issue puzzling is that the line shows up on every unit, across all flexo stations, and always in exactly the same position—just a few centimeters from the plate gap...

 

[Cornishpastythighs]

Thanks for the suggestion. In our step-and-repeat we already include bearer bars on the outer edges, and we also run an ink eater (currently set at 10% on each color). What makes this issue puzzling is that the line shows up on every unit, across all flexo stations, and always in exactly the same position—just a few centimeters from the plate gap...

Thought I read somewhere about checking mounting tape?

 

[Sdbruyne]

Thought I read somewhere about checking mounting tape?

We’ve already tested both hard and soft mounting tape, and indeed we did see some improvement with that. However, on the smaller cylinders the issue still persists.

 

[Cornishpastythighs]

We’ve already tested both hard and soft mounting tape, and indeed we did see some improvement with that. However, on the smaller cylinders the issue still persists.

Maybe you just need to find a tape with the right balance of adhesion, cushioning, and hardness.

 

[brenth]

Do the repeating areas line up with the butt of the tape under the plates or is the mounter using something like a permanent marker to deaden an area on the tape to make plate removal easier for when the job is done? I've seen those cause similar issues in the past.

 

[Sdbruyne]

Do the repeating areas line up with the butt of the tape under the plates or is the mounter using something like a permanent marker to deaden an area on the tape to make plate removal easier for when the job is done? I've seen those cause similar issues in the past.

It’s not related to the butt joint of the mounting tape, and there are no deadened areas marked on the tape either. The issue shows up in a different position.