Sheets Warping after Online coating

[ashwini singh]

Hi,
My name is Ashwini.
we have been facing a lot of problems while online coating on our cd 74L. After printing the sheets tend to warp and develop waves due to which our hardbound books are not closing properly.
We have seen the same jobs being printed by other printers without these waves.
does anyone have an experience with this problem and possibly a solution ?

Thanks
Ashwini

 

[turbotom1052]

Try using a coating formulated specifically for light weight papers.

 

[D Ink Man]

Less water formulated into your coating, higher solids.

 

[ashwini singh]

Thank You.
Shall i do some experimenting with this combination of coating and water ?

 

[turbotom1052]

You need a coating that has been formulated from the manufacturer to run with lightweight stock. I don't believe its something you can do on press. You could however try lowering your dryer temp. I would recommend an attempt at lowering the temp to 88 farenhiet and try to achieve that temp. with hot air only. Do not use your infrared heat at all. You might also try running more coating by either adjusting roller speed or using a different anilox roller if its an anilox coater.

 

[DeltaE]

Have you tried to use "Sheet Decular" in your machine?
This function from Heidelberg helps us to make printed sheet straight after printing process, it could help you some.

And maybe you also check the grain of paper (long grain or short grain), I might help you improved./.

 

[aqazi81]

As stated by others, check your coating viscosity and formulate it to your needs by adding water.
Do you measure your viscosity with a DIN 4 cup?
What is the reading?