Paper warping

[JoshB]

I started this thread in finishing and didn't get a response, so hopefully I'll have better luck here.

We have a process where book covers are printed on Docucolor 5000s, and then laminated with nylon. On sheets with uneven coverage, we get paper warping where the sheet at high-coverage points shrinks more than at low-coverage areas. This will settle out generally given several days, but when we laminate, the warping becomes permanent.

To help this, we tell the Docucolor that the sheet is lighter weight than it truly is. This lowers the temperature enough to reduce warping, but doesn't take care of everything.

Can anyone recommend a good 200~250 GSM uncoated digital sheet that would be more stable? Are there any other simple tricks that might help this problem?

Thanks.

 

[jotterpinky]

I'm assuming you're running the correct grain direction to minimize the curl?

 

[Craig]

By telling the machine the paper is lighter than normal, I'm not sure the fuser actually changes temp. I could be wrong. I think it just increases the speed at which it fuses.

The last sheet I used for covers that were 1 sided laminated was Kromekote 12pt C1S. We outsource the laminating and binding, so I can't tell you much more than that. I think the laminate is referred to as Super Stick???

 

[X33]

Can anyone recommend a good 200~250 GSM uncoated digital sheet that would be more stable?

have you tried Xerox media?

 

[Milo Wilson]

Warping

Warping

The DC 5000 changes speed and the DC 5000AP changes temp and runs all stock at same speed. I'm not familiar with the DC 5000s.

 

[JoshB]

Little bit of confusion here. We're running DC5000 AP, the "s" was an attempt to pluralize, not to indicate the model number. I'm pretty sure that dropping the specified page weight drops the temp rather than boosting the running speed.

We've tried several sheets, though not Xerox. Seems like Xerox would just be buying and relabeling from someone else anyway, so it should be possible to get a better deal on the same thing if we can find the source.

We've been looking at two sided un-coated. We laminate one side (Super stick nylon), and the other gets hot-melt glued. Unfortunatley, the boss is kind of tired of trying different options, so I'm hoping that someone has experience with something that does work well. On the Xerox comment, does that mean that you've tried running Xerox cover and not seen these issues?

 

[JoshB]

Also, correct grain = yes. Curl isn't really a problem. The curl correction works fine, but it doesn't do anything for un-even warping. It's not that the sheets curl nicely in one direction, but that they subtly shrink in /only/ high-coverage areas. This makes an un-uniform waviness that is pretty random and without an overall direction. You can't just bend it the other way to decurl.

 

[print7000]

Have you tryed liquid laminate? No heat is used in this application thus no warping. We also use 1.5 mill Polyester 1 side on Hammermill 80 lb cover with excellent results when Perfect binding. In cases where we must use a specific cover material that warps badly in a toner printer we will run the covers on our wide format ink jet multiple up on the largest sheet we can get. we have adapted ours with an out feed table the same hieght as the out feed of the printer. This alows the sheet to exit flat as it passes over the dryer. This limits the curl introduced to the sheet by the feed rollers. Of course any run larger than 250 or so goes offset, so no prob there. Hope this helps!

 

[sfhellwig]

What type of paper ARE you running? I have operated Xerox machines in the past (wanted a 5000AP, didn't get it) and had good luck with Mohawk Color Copy 98, 80# cover. It is un-coated. I felt it was a good paper all around, very bright and very smooth.

 

[Robertjohn]

My company usually suggests the Hammermill paper, but then again, we don't sell Xerox. I did run into this problem once, with my company machines. The issue was the fusing unit itself. Unfortunately since that whole area has costly parts to replace, I had to lean on my service team to replace those parts so my customer's issue was solved.

 

[JoshB]

What type of paper ARE you running? I have operated Xerox machines in the past (wanted a 5000AP, didn't get it) and had good luck with Mohawk Color Copy 98, 80# cover. It is un-coated. I felt it was a good paper all around, very bright and very smooth.

We're running Lynx 80# Opaque. We've tried quite a few sheets before... I think including Mohawk. This is the best we've been able to find.

 

[316]

i service these m/c's so and that side of things.
By telling the machine the paper is lighter than normal the m/c does drop temp in fuser and at the sometime speeds up.
it sounds like your fuser pressure is not set right meaning it has too much pressure with is causing the warping. So you can try to back the prssure off but be very carefull doing this you can causing fuser off-setting if you go to far.
Now by saying this as a tech i have seen paper stock causing this problem due to rising fuser temp when fusing. the stock absorbs heat and by doing this causes heat to rise in fuser. This is mostly seen in printed stock paper. So i would be trying digital stock. And other causes and i know customs hate hearing this is moisture in your paper with moisture the stock does the same thing rising temp in fuser there for causing warging.
Hope this info hepls you out..

 

[JoshB]

Thanks 316, we'll try backing off on the fuser pressure.

I'm fairly sure that we aren't having humidity issues. We're in a very steady, low humidity environment, and we go through paper fairly quickly.

We've tried several different "digital" sheets, and the Lynx that we're using is recommended for a Xerox process despite the "opaque" name. I'm very open to using any sheet that works better, but so far I don't know what that sheet is.