Screen CTP problem

[maqlatura]

Hi everyone

I have a problem with CTP in company where I work. So, here what's the problem:

We have 2 same CTP-s - Sceen 8300s, one was bought in 2008, and the other in 2010. We use same conditions for exposure for positive Fuji plates, but at the older CTP after exposure appears stain at the place where clamp grabs the plate. After developing this stain looks like a printing element.

Another intersting fact is that plates from other manufacturers (such is AGFA or KODAK) are completely same after exposure from both CTPs and there is not stain on plate.

Hope someone will help me.

Thanx

 

[muneebahmedm]

We use UV inks for printing on metallic sheets so that UV ink can easily dry by UV curing lamp in our printing press.
The problem we are facing is that after 1 complete printing job with UV inks,
the plates which are used for printing become light and we can not use them to print the same job next time.So we have to expose a new plate.
Please suggest some solution.

 

[ansoft]

@maqlatura,
Where are the stains- under the front clamps, or the tail clams? Please check the vacuum and vacuum holes. You can clean under the front clamps. Post pictures of the effect.
Regards,

 

[Johu]

If the stain is under the clamp it can not be on the printable area anyhow...

 

[maqlatura]

@ansoft,
I have cleaned vacuum holes and and under the clamps, but stain is still here. It appears at the middle of the plate at movable clamps. Here are the pictures of the effect, sorry for the poor resolution.

 

[ansoft]

It looks like lack of vacuum. Please attach new tail clamps. If you have older ones-attach them just to be sure that the problem is not in the clamps.

 

[maqlatura]

It was vacuum problem. I realized that after a few cleaning of vacuum holes at the drum.

Thank you