Premature Plate Wear

[Print Monkey 63]

Until August of this year, we were successfully printing runs of 80k to 180k depending on substrates. Since we noticed the premature plate wear problem we have had jobs that needed new plates after less than 30k. At the moment we average a print run length of between 30k and 75k. We have always used a Magnus 800 Quantum plate setter, using Kodak Sonora plates. Our ink and blankets have not changed, but we changed our fount on two machines in April and July and our rollers gradually since in February - all 2015. None of which showed up any problems when they were first introduced. We also have a 3rd machine which still has the original fount but the change of roller manufacturer and this machine has experienced a reduction in a dot gain reduction of 7% in the magenta after a 30k run. I would appreciate any ideas, comments or recommendation please. Thanks.

 

[Cornishpastythighs]

Are all plates wearing out on both of your 1 and 2 machines? Is your 3rd machine seeing longer plate life than the other 2 that have had the new Font change? Can you try and switch your other two machines back to the 'old' font to see if plate life increases?

 

[Print Monkey 63]

Hi CPT, thanks for your reply. Both 1 and 2 machines have similar plate wear in comparison. Depending on the substrate it varies as to which colour wears the quickest. Usually the Magenta, followed by yellow and cyan with black being the least affected. Our 3rd machine with the original fount does not have the problem to the same extent but it predominantly prints shorter run lengths. And thirdly, I was thinking along the same lines as you, and switched one of the 10 colours (machine 1) back to the original fount on Monday of this week. We are currently monitoring this, but not had any decent run lengths on since.

 

[mwc]

Not a pressman here, not familiar with the term "Fount?" (? fountain solution ?)
Anyhow, a few times we have had premature wear on our thermal, processless plates....and if the pressman turned off the oscillators he had better luck....

 

[Print Monkey 63]

Good morning, again thanks for you input. "Fount" is the term we use in the UK so you guessed correctly. We tend not to run with the Forme rollers oscillating only in exceptional circumstances. Although we do run with the "Vario" selected on most jobs. This could cause an abrasive action to the plates that has minimal ink coverage and is something I am looking into.
Wearing out/ blinding......again another issue we can look at; I have a technician from Huber Group coming in this week to monitor the plate throughout and take photo's with a powerful magnifying glass.

 

[goldy]

Its time to go back to basics: Check the ph level of your fountain solution several times during a long run.
check the the plate processing developer temperature. Developer over heating is a major factor at least at the newspaper I work at.
we invested in a processor cooler and our wear went down over 40 percent. (cheap way is a simple meat thermometer).
do a calibration on your plates.
as I said back to basics some times working backward one step at a time can reveal the problem.
Also try a new batch of plates if you can. Everyone gets a bad batch now and then.

 

[Print Monkey 63]

Hi goldy, cheers for the comments - I really appreciate all your advice. I have just acquired a digital pH tester to keep a closer eye on this. We do have weekly audits by our ink suppliers who check the water hardness, pH and conductivity etc. We have a Reverse Osmosis unit to which we add 0.5% of re-hardener- this is checked weekly. And I've just got the lads to flush the fount system and replenish the water, which is something we do on a regular basis anyway. As for the plates; they are process less, so we process them on the press. As for a new batch - we have had this problem for over 4 months now so we should have been through a few different batches. Which may explain why sometimes we get 30k out the plates and other times 60k.

 

[Print Monkey 63]

Heidelberg's - we have 3 different types, XL's, CD XL and the old 4 col 102 - Not all presses have the long runs that show up plate wear but when they do it's common across the board. On the 4 colour at the moment we are changing plates after 45,000 sheets where last year we would have got 180,000 sheets. We are using 2 machines with alcohol on Combifix, and 3 m/c's on alcohol free with Bottcher S 3007 fount and A Huber Group fount Substifix AF. The only common factor across the 5 machines is Plates, Ink and Blankets. Neither the Ink or Blankets have been changed in several years.

 

[Cornishpastythighs]

So what changed if anything 4 months ago?

 

[Alois Senefelder]

I also ask !!!


What as changed ??

1) Are the plates "Correctly Imaged" ?

2) Develop a Set of Plates off Press and trial.


Regards, Alois

 

[Alois Senefelder]

Questions:

1) Why are you not running all the presses - F. S. Alcohol Free ?

2) Are you dosing the Alcohol correctly into th F.S. ?

Regards, Alois

 

[simonw999]

Hello.

I experienced a similar issue with CTP plates from Kodak on a Heidelberg 74.

Ask your Kodak rep to send a press expert down to check the fount.
If you are now running alcohol free your machine minder has to become a bit more aware of the tollerances he can work within.
Your rep should be able to explain this to your minder.

The basics of what is happening (If you find this happens more on uncoated stock) are the coating of the develop on press plate, alongside the dust off the paper stock and the imbalance of fount are creating a sort of grinding paste that is over time wearing the image off the plate.


hth

 

[Dan Roll]

Ask your Kodak representative if this plate is a multi-layer emulsion. I have seen many instances where image loss was associated with the layer responsible for adhering to the plate being inadequately exposed, preventing an adequate bond to the plate substrate. Are you seeing the image degrade in solids and fine dots at the same rate?

 

[Print Monkey 63]

I'll start from the last post and work back - Hi Dan, I will chase up your "multi-layer emulsion" question with our Representative. As far as plate wear goes, it is usually in the Magenta and Cyan in the fine hight-light areas to go first.

 

[Print Monkey 63]

Hi simonw999, regarding our press chemistry, we have it checked weekly by our Ink Manufacturers, and also by our Fount and roller suppliers as well as a Monthly audit. So I am happy with that side. We have been running without alcohol since 2009 and successfully running on Processes-less plates for 3 years so the minders, (of which I am one in my normal roll) are pretty used to the tighter tolerances with this scenario. Yes it does happen more on uncoated stocks and your last comment is something we haven't overlooked.

 

[Print Monkey 63]

CPTthighs, that's the annoying thing, we haven't changed nothing 4 Months ago. The Variable we have changed; rollers, fount solution have been gradual changes over the last couple of years.

 

[Print Monkey 63]

Hi Alois, good questions....What has changed? 1) Are the plates correctly imaged? - I don't know is the simple answer, my background is in print. If anyone can shine a light on this question I would be extremely grateful.
2) Develop a set of plates off Press and trial - We have tried another supplier with exactly the same process-less plates with the same result, ie we use Kodak Sonora and tried Agfa's equivalent. We have tried a set of Ctp Fuji plates from Heidlberg UK which were processed through a wash gum unit. These lasted 3 times longer than normal and we managed 150,000 sheets before visible plate wear.
3) Why are we not running all machines Alcohol free? - we have 2 older machines which are not really designed to run alcohol free. These are on 10% Alcohol with Combifix fount solution. These machines do not normally run long runs so are mainly un-affected by this plate wear issue.

 

[PrepressPaul]

One thing to check and measure initially is the power to plate. I suggest a Stouffer wedge test directly onto the plate. Aim for a solid 3 step. If step 3 is not solid enough, then the plate is not getting enough exposure, the image area is too soft and a shortened life is guaranteed.
If step 3 on the wedge is nice and solid, you can eliminate the image setter from the equation.

 

[Print Monkey 63]

Happy New Year!!! I want to thank you all for your time, advice and expertise in helping with our premature plate wear problem. I had that "Eureka" moment the Friday before Christmas and went home a very very happy chappie. I believe we have found the cause and are currently doing a longer trial. Once I have determined this I will share it with you guys. Once again - thanks.

 

[maas]

Happy New Year!!! I want to thank you all for your time, advice and expertise in helping with our premature plate wear problem. I had that "Eureka" moment the Friday before Christmas and went home a very very happy chappie. I believe we have found the cause and are currently doing a longer trial. Once I have determined this I will share it with you guys. Once again - thanks.

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