plates wearing out

have a problem using process less ctp plates on a 528.
After say 1000 impressions small lines starting at the grip edge of the plate start to work there way towards the back edge of the plate as if some dirt had gone around a a roller.when you take the plate off and hold it in the light, the none image areas are worn away in places.
the plate rep assures me its the fount or rollers doing this.
changed the fount cleaned the rollers, even took them out to check for contamination.
could it be damper to plate pressure?
the stripe seems fine.
maybe the damper has gone to hard with age/impressions?
any advice would be great.

 

Could be many things...you need to do provide some more info first...

How are your packings plate/blanket - how's your print length? Are your print pressure correct (and don't just trust the dial they can misread so easily)

Are your dampeners geared or are they delta effect? Deltas run slightly slower in circumferencial speed than the plate cylinder and so slip against the plate to scrub the surface, eliminating hickeys according to the theory, so if your fount/wetting combo is poor then I'd expect excess wear particularly if your settings are overhard to the plate.

What condition are the forme/dampener rollers in? If they're old and shiny then maybe it's time to recover them.

Are the 'lines' grooves ie do they have depth? Could be grit carried on the surface of the sheet...this would affect the 1st print unit more than the others.

Is the wear confined to one unit or all units. Mainly in the non-image area? Confined to one side of the press...same side every time?

Check these items out and see what you come up with.

 

cheers Richard gonna see what the go is today when i get on shift.
i suspect the rollers need replacing as they are shiny.As for grit getting onto the sheet that is another factor as my shift partner has been using spray powder excessively.I was getting the problems on backup and cleaning the blanket allot although i started a new run on fresh stock and the problem arose within 1000sheets.maybe its the water, were having big earthquakes here in Christchurch since february, alot of crud has been shaken up.

 

Not familiar with that press, but we were wearing plates out because a guard was rubbing on it. Both nip guards. If it were your rollers it would not leave straight lines as they oscillate. Hope this helps.

 

Not quite so HPC...forme rollers don't oscillate (on Komoris) unless they're the special option A and D roller.

 

Senior moment, they don't on our presses either. Just check your nip guards then?? Thats all I got.

 

Senior moment? Welcome to my world

 

Hi Andy
I'm sure we both experiencing the same problem. I'm experiencing a similar problem on Kodak Process less Plates on both my Komori 526 and 528 presses.
We also noticed we don't get the same run lengths as what we used to get. We tested dampers, Form roller pressures checked blanket and plate packing. But still have not found the solution. Recently the Plate supplier has told me that the Ink we using is causing this, (which i find to be a bit ridiculous, cause we always used the same brand over the years). My latest theory could be the the coating on the plates are not as good as they used to be....

 

Maybe the plate supplier has a point...some inks carry coarser pigment (so they don't have to add as much maybe).

We use TOYO Hy-Unity which make a point of their 'fine milled pigments' - recently changed over to Azura V plates (lo chem) and haven't had any issues other than poor quality control - lots of fine scratches straight out of the pack.

But I think you are equally right - the plates these days aren't as robust as they used to be.

 

We too use the azura plates, and have found them to be not near as good as the older plates we used to have. We develop the lines you speak of and have traced them back the dampner form roller. The only thing we have tried that works is changing that one roller. The problems for us usually come around when we run dirtier stock, we do not have a dusting unit.
That's probably not what you want to hear, but it was our solution to that problem.

 

we too have traced the problem to the damper, alot of our stock is 80gsm offset with leaves alot of sedament on the blankets etc. we have found that giving the rollers a wash with a good decalcifier after long run 80gsm offset job keeps the problem at bay. cheers for the input

 

We also see we do not obtain the similar run length as what we used to get. Be your dampeners geared or are they sink result? Deltas run barely slower in circumferential speeding up than the bowl ram and so mistake adjoin the bowl to graze the surface, eliminating hickeys according to the theory, so if your fount/wetting admixture is poor again I'd apprehend balance abrasion decidedly if your settings are overheard to the plate.

 

When we were looking at our latest ctp device my boss came across a news artical stating the Kodak had bulldozed the manufacturing plant that made lithographic plates, and was now farming out that part of there operation in a cost cutting measure to a plant in China. This would also affect other companies that Kodak supplied plates too.
This industry is changing how things are made, and sometimes problems pop up because of the sudden change, how we react will be the test. If keeping your rollers fresh and new, well so be it.
FSA

 

Hi it might be scanlines on plates make sure the plates are not under developed. I have had the same problem

 

hi there, i also had the same problem using kodak process - less plates. 1st side i could get about 25000 to 30000 impressions out of them on a good coated stock however on the back up i had trouble getting 10 000 imp. it turned out it was the spray powder like you thought ( its the main difference between the first and second sides anyway) we changed brands and grades of powder and it made a huge difference. those plates are really sensitive to abrasion . i could only get about 15000 imp on uncoated stocks because of how much crud the blankets pick off/out of the paper.
on a similar theme i could never use strong plate cleaner on them either and they would oxidize after stopping the press for any longer than a few seconds. i hated them but a bloke on another press didn't have the same trouble. it turned out that was the fountain solution, i ended up on a 6 col Roland that was chemically maintained by Bottcher (they would check all the levels every couple of weeks and adjust to keep everything, like fountain solution in its optimal range), and this press had no trouble with the same plates, strong plate cleaner and all

i feel your pain having an operator on another shift running too much powder as well. some guys just don't get it!

 

Ive been having the same problem with kodak plates on my komori l_840, We tried every thing from chemistry to roller settings, and we still were lucky to get 1000 impressions out of them. we recently tried a higher quality fuji plate and the problem went away.

 

Hi Guys,

After doing some tests i found that, Calcium build up on rollers can effect the plate. Frequent De-glazing helps to resolve the problem.

 

Has this always been a problem or something that started with a change to processless plates? Is the machine a NL528 or normal L528? There are differences in the NL damping that can cause problems like these.