Plate wearing and paperdust on plate

[platterkotten]

We have a problem with plate wearing. The plates is worn out after 10.000 copies. We have checked the foundation and its good roller settings is good too. The plates have a thin layer of paperdust after a while in production.
What can the problem be?
Can it be a calcium problem?

Heres a picture of the plate.

 

[john beniston]

It may very well be a calcium associated problem .
I see from the photo graph that the non image area of the plate is sensitive.
So the fist question to ask is what is the pH of the dampening fluid like?
The pH should still fall in the zone 4.5 - 5.0
Have you had problems with the paper in use before .
Sometimes an acidic fount solution is strong enough to leach calcium out of the paper . It gets in the rollers and starts to inhibit ink transfer. It can neutralize the mixed dampening solution. When this happens, not enough
Desensitizing salts can be formed to keep the non image areas clean and sharp and that's what I see happening here.
If this is what is going on I would get some help from your supplier of fountain concentrate may be they have one that will work more effectively with the paper you use. Also you should be using a good roller maintenance program weekly which includes a calcium treatment for the inking rollers . If you do not then you will start getting poor ink transfer and ruined rollers.
Sorry not to be more helpful. Good Luck

 

[Dan Roll]

Are the streaks in the solid around the plate or across the plate?

 

[platterkotten]

Thanks for replying.
The PH is at 4.94

Yes we have had this problem before it comes and goes for some reason.
The streaks are across the plate.

And the vineager solution seems to work well. We just printed 20.000 copies without any streaks in the printed copy. But thats not the final solution.

 

[Alois Senefelder]

Classic !

Classic !

Hello platterkotten,


What you are seeing on the plate are - Gear Streaks, what make of press ? is it just on 1 unit or more than 1 ?




Regards, Alois

 

[Armya Inc]

We have a problem with plate wearing. The plates is worn out after 10.000 copies. We have checked the foundation and its good roller settings is good too. The plates have a thin layer of paperdust after a while in production.
What can the problem be?
Can it be a calcium problem?

Heres a picture of the plate.

Back to Prepress room. What brand of Plate are you using? Thermal/Violet? What kind of processor?

 

[platterkotten]

Alois: No its on more than one unit. But most on black and magenta. The press is a Manugraph Hiline 45.

Armya: We are using Agfa plates, Afga ozazol CTP. I think its a violet and flatbed laser. Im no prepressman

I think our problem has 2 sides 1 mechanical and 1 chemical.

 

[platterkotten]

Any more suggestions of this problem?

I can say that we have pretty much paperdust on both ink rollers and damprollers too.
We are cleaning our blankets twice a day.
And printing on uncoated improved newsprint paper.

 

[Dan Roll]

I would look into the relative heights of the plate and blanket surfaces. If the diameter of the plate cylinder (including plate and packing) is different than the diameter of the blanket cylinder (including blanket and packing) the speed of the two surfaces will not be the same and when you add some abrasive material like paper dust, you will start polishing the plates in stripes that go across the cylinder. Modern plates have fairly soft image emulsions and will not stand up to much friction. I would pack the surface the dust builds up on (I am assuming this would be the blankets) a little lower than the plate so when the dust builds up on the blanket the blanket surface speed will tend towards equaling that of the plate, rather than trending further from equal.

 

[platterkotten]

Dan roll your idea sounds good. The blanket is a bit higher now than the plate. We have a bit of overpacking on the black unit because we had problem with bad impression to the paper. And we are not using any type of packing under the plate ar all. Can tell that the press has bearings too.

 

[printecx-ch]

Hallo, ich schreibe auf Deutsch, mein Englisch ist nicht so sonderlich gut, bitte Google Ãœbersetzer verwenden.

Ich habe Ihr Problem an Hand der Angaben so weit wie möglich lokalisiert. es sind eine Summe von Problemen.
Calcium ist nicht das Problem, etwas ist auf der Platte vorhanden - was auch nicht sonderlich gut ist - kann auch behoben werden.
Das Problem ist mechanisch. Allerdings muss das über die volle Zylinder - Breite untersucht werden.
Es gilt zu erkennen: Sind es Zylinderverbiegungen, oder sind es Streifen aus dem Getriebe.

Fakt ist, Ihre Platten sind an den hellen Stellen durchgescheuert. Das Problem was Sie haben, hat nichts mit der Platte zu tun, ob widerstandsfähig oder nicht, sondern mit der Maschine, evtl Zylinder - Probleme (Unterlagen, Aufzug usw.)

Meine Kontaktdaten sind auf : www.we13.ch/printw11.html

Sie dürfen mir gerne schreiben.
Max Lüthi

 

[tamale]

It appears to me to be a paper issue. If you are having problems with paper dust its probably because the paper is not well sized and newsprint is rarely sized enough.

Also it may be an issue with newsprint that has a very high recycled content. Recycled fibers are much shoter than virgin and do not adhere to one another as well as virgin fibers do so they tend to pile on the blanket.

You want to express the problem to your paper supplier who may suggest another grade. In the meantime try an ink reducer, this will lubricate the plate and blanket with the result of sometimes completly eliminating the problem.

Tamale

 

[ctprudman]

Single layer plate technology is better for mechanical wear double layer is better for chemical attack - a correctly or even a part baked single layer ctp thermal plate wll be better than both of the first two mentioned ....and you can iincrease the baking time till you acheive what you need for your maximum run requirement.

The time needed to maintain good press conditions has been lost in todays market at many sites , paper quality is dropping due to increase in pricing - a few cents more cost for each plate made in the plate making area could save you 1,000s and a lot of heart ache

 

[D Ink Man]

I would stick with the vinegar washes and cleansings. Have your inkmaker add lubricative compound to the inks to prolong the build up. Changing paper stock may and usually is not an option for printers. I would recommend 1.5 oz to a pound of either petrolatum, microcyrstalline was compound, orange solid oil or even a commercial vegatable oil compound like Crisco. Try it yourself first, and then have the ink supplier incorporate into the formula. Don't be afraid of the 10% cut, it should work.

D Ink Man

 

[Rickyo]

I would look into the relative heights of the plate and blanket surfaces. If the diameter of the plate cylinder (including plate and packing) is different than the diameter of the blanket cylinder (including blanket and packing) the speed of the two surfaces will not be the same and when you add some abrasive material like paper dust, you will start polishing the plates in stripes that go across the cylinder. Modern plates have fairly soft image emulsions and will not stand up to much friction. I would pack the surface the dust builds up on (I am assuming this would be the blankets) a little lower than the plate so when the dust builds up on the blanket the blanket surface speed will tend towards equaling that of the plate, rather than trending further from equal.

I like that sugestion,I agree packed tad heavy maybe