Heidelberg xl 106 ink density

[Nick102]

Hello all
I run a 2020 xl 106 one over one. Run primarily black color. We run an axis control scanner with automatic ink adjustments. At 300 sheets the curve brings the ink in nicely. But after 700 sheets the Ink completely drops on the last 7 gives on either side of the sheet by 20 points. This is on 29 1/2 x 41 inch paper uncoated. The Ink is not emulsied. Ink will come up to color but the keys are much higher then the rest of the sheet and there is nothing out there but a density box.

Thanks for sny help

 

[Beguin]

hi, please could you show us pictures of what you said so we can better understand the problem! thank you and god bless us.

 

[Nick102]

Yes I can here you go

 

[Nick102]

Water pan is set if I close it any more it will run dirty. Water percentage is as low as I can go roller to plate stripes are set

 

[Steve F]

Puzzling...

Initial thoughts would've been the pan roller, but that's obviously set ok.

Other thoughts:
Ink form rollers giving a solid even stripe, edge to edge (particularly 1&2)?

If you're getting good densities early in the run and then dropping off after several hundred sheets that could show the curve is actually off.
As when you start, the amount of ink on the rollers is correct, as the previous job running will have settled down the ink level, so the inking level will look good, then as you're running the reloaded the default characteristic curve will start to under ink the very low coverage areas towards the edges again, and if it's under inking by a lot, it will over react by quite a lot. So maybe the curve needs increasing a little for low coverage areas?

I see you're using the micro colour bar and personally i much prefer the standard size 4-col bar, as on a large thin wavy sheet it doesn't take much movement for the Inpress scanner to see a bit of white paper next to the small colour bar square (especially up the edges of the sheet) and therefore under read the actual density of the bar. Ideally I like to see the colour bar in the grip.

Damping speed-compensation problem? I've never altered that so I've exhausted my knowledge on it already

Steve

 

[Nick102]

It was the roller to roller stripes and the curve rest both today on one until made a huge difference. Thanks for all the input.

As for the micro color bar I don't have a choice but to use that. Comes from pree press like that

 

[turbotom1052]

Seeing how the largest cost center in most any commercial printing plant is usually the pressroom, I find it odd that the pre press dept dictates to the pressroom how things are going to be. This usually occurs when the "suits" are guys that have come up as pre press guys, or are of the thinking that the dirty end of the biznez somehow doesn't deserve priority. It never ceases to amaze me how at times, supposedly smart businessmen, can be so stupid!!! If you are reading this, and you are either a company owner, or someone in a position to set policy company wide, then I suggest you just crunch some very simple numbers, and see just what part of the company, cost you the most to operate. Once you see what im talking about, you would be a real simpleton to not realize that the dog needs to wag its tail rather than the tail wagging the dog!!!

 

[William Dubuc]

Hello all
I run a 2020 xl 106 one over one. Run primarily black color. We run an axis control scanner with automatic ink adjustments. At 300 sheets the curve brings the ink in nicely. But after 700 sheets the Ink completely drops on the last 7 gives on either side of the sheet by 20 points. This is on 29 1/2 x 41 inch paper uncoated. The Ink is not emulsied. Ink will come up to color but the keys are much higher then the rest of the sheet and there is nothing out there but a density box.

Thanks for sny help

You need to squeeze your metering roller slightly because you are getting to much water on the plate.
The scan will flatten out for you