Mitsubishi Help

[Chiefs420]

We run a Mitsubishi ECO 1630 III R. Every so often on one of our presses (the 4 color Heidelberg) we get strange little spots on the plates and they transfer to the paper. Sometimes they are on all 4 plates other times only on one, two, or three. This doen't seem to be an issue with the other presses. The rep that sold it to us keeps telling me to clean the plate setter. I clean it as much as is humanly possible. Has anyone else had this problem or have ANY suggestions as to what it might be? Any help would be greatly appreciated.

 

[Tommy B]

Eco 1630

Eco 1630

It sounds to me that the Eco is fine and I would look at the chemistry being used on the press. Is it different than your other presses?

 

[PrePress Gal]

If you find out what it was, I would like to know. We had the exact same thing happening and Manager just kept blaming it on the platesetter (couldn't possibly be the press, even though the pressman thought it was).

All of a sudden they went away, but it has done that before. You're right, the platesetter couldn't possibly be any cleaner than what it was. The ONLY thing that changed in prepress was that it was calibrated and the temperature unit was about 6 degrees low. We were losing the right end of our gradient screens on long runs because the density was off a bit. Whether that had anything to do with fixing it, I don't know.

Just some ideas.

 

[Chiefs420]

He grudgingly changes chemistry to the stuff that is supposed to be for the polyester plates we run, but that hasn't done any good. When our xpedx rep came to look at it he said it needed cleaned and gave it a thorough cleaning and I have kept it at least as clean since then.

That was only a month and a half ago. The pressman is convinced its not his press and when the rep told him that he thought the platesetter needed cleaned he had heard what he wanted to hear and now the ball is back in my court.

I have an email in to mitsubishi but no word back yet. I'll keep you updated. It is nice to know that i'm not alone. Everybody else i've talked to says they have never heard of such a thing. Of course those are the people that would have to fix it if something else was wrong.

 

[Chiefs420]

The ONLY thing that changed in prepress was that it was calibrated and the temperature unit was about 6 degrees low.

I just calibrated it last time I cleaned it, two weeks ago, and my temp was at 91f, which is right in the recommended spectrum.

 

[DonBlock]

I'm always amazed at the total lack of common sense of some people, usually the pressman who has the perfect press and nothing ever is wrong with it.....

Are the spots really on the plate, or does it just appear that way? When in the run does this issue appear? What happens if they clean the plate, properly, and start back up, or just examine the plate where the spots are to see is what is there?

It sounds like a dirty press issue to me with excessive paper dust going throughout the press.

To understand the Poly Plates, they are a Negative Plate in the fact that the black part of the plate is what is being imaged and the silver image is what is left. For the plates to have a problem like that, there would have to be something blocking the laser so it did not image in that spot. This is not impossible, but it would be in the same location and on every plate.

What other presses do you have and what are the size of the plates? Could you take a plate that was showing this issue and clean it, cut it down and run on another press to see if the problem was still there?

These things are not that difficult to track down if all have an open mind and just think logically.

Also, make sure they are not using any Etch on the press. I really don't think that would cause this problem, but Etch will attack and deteriorate the plate.

 

[Chiefs420]

OK, here we go:

All of this was suggested by the Mitsubishi tech I talked to on the phone and it really does seem to be helping. Also I clean the hell out of it every two weeks. Its a real PITA, but as I said before it seems to help. Maybe to the point of taking care of it all together. Our pressmans been running metal plates for the last week or so (long runs) and has only run the poly's sporadically. He did 5 photo b cards in one day and the first ones the only one that spotted and that one wasn't horrible.

So Ive been emptying the water every night and replacing with fresh reverse osmosis (Culligan) water every morning. On Friday I empty out the activator and stabilizer then flush out those tanks several times with hot (not too hot) water. After the liquid coming out of them runs clear I fill them up with water for the weekend to keep the insides from drying out and flaking off into the fresh solutions I put in on Monday mornings.

Also there's a roller in the middle of the rack that you take out to clean (the rack, not the roller). its the one basically in the middle, above the metal knurled knob you can use to manually turn the rollers inside the rack. It needs to be black, if its silver or tan looking you need to get a green scrubby (scotch brite) and scrub the hell out of both top and bottom rollers (again this is from the tech guy). He seems to think that that has really helped too as mine was pretty tan in color. It took some scrubbing the first time to get it back to black, but the last couple of times, not so bad.

The tech guy lives a few hours away and is planning on stopping by sometime (hopefully soon) to take a look at it. I'll keep you posted.

 

[Lee Ornati]

Spot on Mitsubishi Plates

Spot on Mitsubishi Plates

It sounds like a combination of under exposure on the plates, and emulsification on press. If plates are underexposed the black, non image area can attract ink. If the ink gets emulsified on press little chunks of ink can attach to the plate surface. Try resetting the exposure. Also possibly you are mixing your fountain solution too strong, or the ink is too soft. If you want to send me a sample of the plates, showing the problem I can make a recommendation. You can set that up by e-mailing me at [email protected] if you are still having the problem.
Thanks Lee
Mitsubishi Imaging Inc.

 

[Pressman's Pride]

Plate spots

Plate spots

This problem is inherent in the poly, when you run certain ink pigments it happens more than others. I have a combination plate cleaner that solves the problem, my own making. Samples available but I am currently selling it to several guys running polyester, they all come back time and time again for it. 1st time every time it works and gets rid of the spots for the entire run.