KM C8000 wavy paper and curl problem

[M@CK]

Hey guys, just installed a C8000 and from the start I noticed that thin uncoated papers would come out wavy and get even worst with time if I let them sit over night.
I have a very controlled environment with 40% humidity at all time, I even let the paper sit exposed at least a day before printing on it, still wavy.
Now my tech tells me I should buy the Humidifier for the C8000 and that wold almost totally solve my problem...
Also wen I print on say 12pt gloss I don't get the wave but cant un-curl the paper it will bend one way or the other.

Any one else experienced these issues ?
How did you solve them ?

Thanks for the feedback.

 

[mutti8000]

It is a copier, paper will curl, it is on of the of the side effects when paper is heated in the fuser(s)
The humidifier will help you a great deal. Also try to experiment with the decurler function in you paper catalog.

 

[pacart]

try turning the heat down on the text weight papers, we have the older konica/minolta 6501 and we usually turn the heat down for the text weight paper.

 

[KopyBoss]

Use the curl adjustment and humidifier setter.

 

[lfelton]

I think you should check the facts carefully on this one. As far as I am aware (we have a c8000 with the humidifier), it ONLY works on uncoated paper. If you are counting on this feature for COATED paper, I think you have been misinformed.

If you have CURL, the decurlers work very well.

If you have WAVE, this is something that all fuser based printers suffer from to one extent or another, however we have found that wave is reduced if the machine is properly maintained. For instance on our 6501s, wave is much worse towards the end of the major service time. To reduce wave you need to consider 3 things. Firstly, the grain of the paper. LG SRA3 will tend to exhibit less wave than SG. Second, the moisture content of the paper. A higher moisture content will typically mean more wave. "Digital" specific paper will have a lower moisture content compared to standard litho paper (but will cost more). Thirdly, "conditioning" the paper in your factory. In my part of the world it is pretty cold at the moment and paper merchants stock their paper in unheated warehouses. This means that the paper is freezing cold when it arrives and that will cause all kinds of problems (even with tray heaters) if used straight away. We typically store digital paper in the nice heated room WITH the digital printers for several days before use.

You probably knew most of that anyway, but I hope it helps.

 

[arossetti]

Not to make this a Xerox vs KM thread but one of the reason we went with the 800 over an 8000 is the cooling unit of the 800. My sheets come out straight as an arrow between the cooling belts and the decurlers. So I think digital technology is finding a way to deal with wavy stock and it is no longer an issue you have to deal with no matter what.

 

[lfelton]

Well the samples that Xerox did for us on an 800 (actually a 1000, but I think the same basic machine) came back with a pronounced wave in them. I don't doubt your experience, but I've seen no evidence with my own eyes that any manufacturer has yet perfected high temp fusing + standard litho stock paper level moisture issues. Printers who do a lot of book printing would love this on colour toner + FUSER machines, but then again I guess digital printer manufacturers see that market as a steadily shrinking one (and most of the bigger printers are field testing production inkjet in any case).

 

[DennisTd]

I installed a C8000 on January 2nd of this year and am experiencing the same curl problem that you are writing about. I already had the C7000 with the C8000 being my second unit so I am quite familiar with the KM product line. KM still has not been able to solve the curl problem printing on heavy stock on this unit. I did not purchase the humidifer kit but the ended up installing it to try to solve the problem which it did not. Currently we are only able to print by outputting to the end of the copier and small stack tray rather than the high capacity stacker which we need. Most of the product we print is variable and addressed as it comes off of the machine.

I had a discussion with KM last night and I am about ready to return this unit if they cannot get this addressed. Has your problem been solved yet? I would love to hear what they are telling you or what steps they took to solve your problems.

 

[arossetti]

Well the samples that Xerox did for us on an 800 (actually a 1000, but I think the same basic machine) came back with a pronounced wave in them. I don't doubt your experience, but I've seen no evidence with my own eyes that any manufacturer has yet perfected high temp fusing + standard litho stock paper level moisture issues. Printers who do a lot of book printing would love this on colour toner + FUSER machines, but then again I guess digital printer manufacturers see that market as a steadily shrinking one (and most of the bigger printers are field testing production inkjet in any case).

That has a lot to do with the operator and how they have the paper stocks setup. Using the stock library and IOT curl settings plus using the 2 decurler adjustments on the transfer module and finisher should garner straight sheets. The person who printed the samples may not have had those settings properly setup.

Edit: Also all of our house stock is digital paper. We only run litho for special orders, usually those are for heavy weight stocks which tend to lay flatter.

 

[rsands]

For light stock decrease the fusing temperature. it can be too high be default and causes bad curl.

ON our machine the curl menu is back to front...so check its not on yours..its to do with how the machine flips the sheet. There is DIP switch settings which control a roller for curl. Its the roller just before the 2nd fuser unit. it can be set to different levels but you need to get into the dip switches. Service guys will be able to adjust for you if you dont have access. Its handy to have access though as we adjust sometimes for different stocks

rehumidifier - forget it...waste of water and time. They ripped ours back out