Lines across all units

[anuj]

Hello to everybody, would be grateful if someone could advise how to get rid of lateral lines which we have been experiencing on our KBA rapida 104-5 on all 5 units. Surprisingly all units print the lines exactly at the same place, we changed the main motor bearings which did not help, we then changed the main flywheel bearings which also did not help.

The lines show up when printing solids and dont show in halftones. All rollers are new.

All help and advice is welcome.

Thank you.

 

[Hawker]

Hi, firstly I would solve problem by process of elimination. To begin I would take a solid print without using the dampers, if the lines have gone, then it is the dampers. Probably a roller setting in the dampers.

 

[anuj]

Thank you Hawker, I am grateful for your time and interest. We had already tried the elimination process as you mentioned. Would request you to please suggest something else. We see no noise of faulty bearings etc.

Could it be due to some issue with the ink forme roller bearings.

Thank you again.

 

[Hawker]

Anuj, how far back from the grip edge are the lines?
For now adjust your circumferential oscillation slightly on one unit and see if the line changes position. If the lines move, then adjust them until it is in the plate gap. I know this doesn't solve your problem but will hopefully get you out of trouble. The fact that it's happening on every unit suggests that it's not forme roller bearings. Is there anything that you have altered or replaced recently on every unit?

 

[FFR428]

Excessive end play in the rollers (ink forms mainly that I've seen) could cause a line across the blankets. I know on my old Komori I had some adjustment for end play when installing new or recored rollers. I've seen it on smaller offsets too. Just a thought?

 

[spike]

anuj have you tried different inks? or fountain soloution.

 

[rking]

Hi Anuj, did you ever solve your issue or figure out what is happening? We have same issue.

Thanks,
Rking

 

[Hman1956]

not if it's in all the units, at the same point.

 

[Hman1956]

it could be the "gap water" on the water form. try turning off the delta and see if it goes away

 

[turbotom1052]

Are you certain that there is not a slight defect in the paper thats not visible until you put ink on it? Sometimes you can use a black light to inspect the sheet for such defects, that remain invisible to naked eye in normal lighting conditions. I only suggest this because you mentioned that its in the very same spot on all units!!!

 

[Abhi]

I'm curious to know the reason if it's other than paper stock issue.

 

[turbotom1052]

you might try lifting ink form rollers off the plate, one at a time, on each unit to see if the issue changes.

 

[PB Leaflet Distribution]

Sometimes you can use a black light to inspect the sheet for such defects, that remain invisible to naked eye in normal lighting conditions.

 

[mlena]

Anuj, Did you find any solution for this problem?

 

[georgbob]

I suspect this is cording effect. The problem is the ink and water additive's connection.