Axis Control issues on '06 SM74-4

[Albert Noel]

First let me start by saying the press has been installed for about year now and I've been operating it for about 9 of those months. I spent 11 years prior to that at another company operating a Manroland 305 and so this is my first experience with an SM74 (previous experience on Heidelberg is just a QM46) it's a 2006 model with a coater and axis control (spectro?)

About a month and a half ago we had serious power issues with a storm that rolled through and essentially had virtually every piece of electronics in the press replaced (no.. i'm not joking)

The scanning head was checked out and given a clean bill of health and seems to have been working fine ever since (and was even checked by heidelberg techs) however it's giving me some real issues with colour control.

I'm not sure if some software values got corrupted or if the press learns as it goes but it takes several scans now to get to a specified target for colour. Initial run ups are no where near correct anymore (we figured this would need some tweaking after the values were wiped out but there just doesn't seem to be any leeway) After running up the green circle/hourglass it takes at least 4 or 5 scans and corrections to ge the press into the right ballpark. After that it seems to be a yoyo effect and can't seem to hold colour. (it's as if the press is overshooting the corrections and cant seem to make fine adjustments. This happens with colour booster on or off.. just happens faster with booster on)

It's resulting in longer make readies and much more waste (you can only pass sheets through so many times obviously)

To get around this, I simply scan and make corrections by hand (though even then if i send in a scan correction mid run it swings dramatically.

I've calibrated using the card that came with the press and curves are whatever had been programmed in by the previous owners (we never changed it and they seem to be in tact) the target densities were wiped out but we plugged in our own (maybe thats the problem?) Is there a specific method that the system should use for scans? (polarized versus non polarized? angle? whatever other settings are in that menu that happen to be slipping my mind at the moment?)

The owner is getting a little annoyed that it's not performing correctly and service techs seem puzzled and insist its working correctly and to just "check rollers".

Any insight?

 

[Ozkan Hangisi]

I would measure same sheet several times to check whether the measured values are always same. If not, clean glass and spectrolino lens. Also check rail is clean and oiled well. Movement along the sheet must be smoth.

I assume you care about job change from high coverage to low coverage. If a low coverage job starts with too much ink on rollers, it is pain to achieve target colors.

Trying another brand ink might solve problem

Also perform CIP3 data calibration. Starting with good CIP3 characteristic curve, helps for fast correction.

Check press machine. Make OK sheet. Don't apply correction and print 200 hundered more and measure again. Do it several times without correction. If serious deviation happens, search problem in press.

Good luck

 

[jbeniston]

Hi Albert, it took you long enough to get off that press, now I see you are running a Heidelberg.
It sounds to me that the damage done by the electrical storm has really screwed something up and I would think you need to get Heidelberg involved get your owner to ratchet up your requests for assistance, a couple of notches and get a specialist over there. Make sure you have everything carefully documented for him and that you can describe carefully the problems that you face during the run and so on.
Good luck