Cleaning hot spots on kodak thermal plates

[appstro]

Anyone have a fast effective way to do this? Right now we are using a solution, then plate cleaner to remove the spot, then we run the plate through the processor (rinse and gum) to re gum it.

Also, we get an awful amount of hotspots sometimes. I am not sure if its the humidity or what. Any ideas on what could be causing them? I wipe down the drum on our Magnus 400 every day...

 

[marktonk]

Re: Cleaning hot spots on kodak thermal plates

appstro,

We use to have this problem with hot spots on Topsetters. The laser had a very shallow depth of field and dust on the drum would cause hot spots. With the Suprasetter, we have a large depth of field, so this eliminates most. Do you have a Magnus 400 with the Quantum laser? This has an auto focus system that should also act like large depth of field and eliminate most hot spots from dust on the drum. If you do not have the Quantum laser, I am not sure if the fiber laser has a large depth of field or an auto focus system. If it does not, this may be the reason why you have hot spots. Another cause may be attributed to plugged vacuum holes. What plate are you using?

Regards,

Mark

 

[SteveAgfa]

Re: Cleaning hot spots on kodak thermal plates

appstro...

Is it cold & dry now where you live?

Perhaps you have low humidity, which can
cause static cling. A humidifier might help
in your room. Of course - always follow
your system manufacturers' recommendation.

Regards,

 

[appstro]

Re: Cleaning hot spots on kodak thermal plates

Thanks guys. Thats interesting considering the laser. No we dont have the quantum laser. Part of the problem is that we did a laser adjustment because we were loosing all of our 3-5% screens. The laser just seems to blow them out and they never appear on plate. So we did an adjustment. Now we are getting the screens, but we have at least one hot spot every day. On dryer days I think we get more. I have been told thats silly though..... I still think humidity is a factor here. I have asked that we increase the intensity of the laser again just a bit, but they dont want to loose the screen. Ugh.

We are using the kodak sword ultra grain plates. I try to clean out the vacuum holes once a week. Sometimes I will let it go for up to three weeks, but never more than that. I also have issues with the auto cassette loader its a pile.

Edited by: appstro on Jan 21, 2008 12:42 PM

Edited by: appstro on Jan 21, 2008 12:43 PM

 

[G_Town]

Re: Cleaning hot spots on kodak thermal plates

Is the head focused properly?

Just cranking up the intensity isn't the answer as you see when you start to lose your H/L dots, did you adjust it or did a Kodak engineer? I'd get them in and have them varify focus, intensity drum speed the whole 9 yards to make sure it's not your unit.

I used to run a Lotem 800 with swords and we never had any spot issues even if our humidity went way down.

 

[dub]

Re: Cleaning hot spots on kodak thermal plates

With the Sword plates you will want to look also at your scrub covers, how often are you replacing them? Also make sure you do a stripe test on them every time you change dev. (8-10K sq. feet thru the machine) and adjust as needed. Also may want to see if you get more hotspots near then end of a chem cycle, could also be replenishment rates and dev. getting weak. You will also want to clean off the rubber rollers that contact the drum in the Magnus as well (ours are a pale blue color) they get a lot of build up and cause scratch looking spots when they get dirty.

Good Luck!!

 

[appstro]

Re: Cleaning hot spots on kodak thermal plates

I agree with both of you guys. Yep, I clean the beast once a week, just like the manual suggests. clean out vacuum holes, wipe down the drum with an anti static towel ( Dust Bunny ) , Rubber Renue on the cups, pinchers, rollers, wipe down unit with wet towel on the outside. Periodically I clean the lense with a q-tip which is a pain in the arse. I change developer filters every 500 plates and change chemistry, developer, and all filters every 1000 plates. Scrub roller test every other 1000 plates. I have replaced the scrub rollers about once every 6 months.

We had the damn thing pretty much dialed in until one fateful day. I didnt shut the door evenly enough on the top of the unit and the high pitched sensor alarm went off. When that happens you have to basically shut it down and restart it (the CPU). So I went around back and hit the yellow power button. That pretty much killed it for good. When I restarted it, it somehow developed a hard drive reading error....a fatal one. We were down for 2 days! When I called Kodak the guy asked me when was the last time you backed up the magnus? I said, Wha??? What do you mean? He explained that you need to back up the configuration settings at least once in a while. That way if you do loose a hard drive you simply pop another drive in, format it and load the old configuration. EASY. Well, we lost all of our settings and after that it was one thing after another. We had a Kodak rep come out and work on it for quite a while, but it was never the same. They did some tests, and have not been back. My boss is aware that we need to get kodak back out here but he wont schedule an appointment. We no longer have the maintenance contract so it costs us dearly every time they come out. We DO need them to come out again though.

Well it sounds as if this issue is beyond my control. Thanks for your answers guys.

Edited by: appstro on Jan 21, 2008 3:41 PM

 

[marktonk]

Re: Cleaning hot spots on kodak thermal plates

appstro,

If the hot spots are only on the edge of the plate, the plate may have a rough cut leaving burrs. This was sympton on a Topsetter which did not have large depth of field or autofocus. funny, We were told by the plate manufacture to used a metal ruler on the edge to deburr the plates. This actualy worked but was not too practical. Good luck.

Regards,

Mark

 

[appstro]

Re: Cleaning hot spots on kodak thermal plates

Thanks, but no the hot spots are all over. The ones on the edges we call "flares" heehee....Dont get too much of those on the big plates, but alot on the dick and jet and didi. The small pressman hate them.

 

[Jackie]

Re: Cleaning hot spots on kodak thermal plates

appstro,

I'm getting hotspots as well but generally just on my smaller Hamada and AB Dick plates, the larger Komori plates are no problem. I find that constantly cleaning the drum keeps it down to a minimum. Any small bit of lint or dust will do it. I get "flares" as well on my plate edges.

As for getting them off your plates after the fact I guess it's a plate by plate situation. With my sword excel plates I just have to use a soft wipe and a bit of developer to get the spot off and then regum.

I wonder if there is a way to increase the vacuum suction and if that might help. I'll have to ask my Kodak service rep when she pops in.

 

[dwaltmire]

Re: Cleaning hot spots on kodak thermal plates

We have Screen PlateRite 8000II platesetter running Kodak Sword Excel plates and we get spots, but not sure if they're the same kind of spots all of you describe as "hot spots". These spots look like focus problem, are seen through lupe as having lines, with the overall shape being round to oval, usually about dime sized, maybe due to dust under plate, can be located anywhere on plate, but are impossible to see before the plate has been inked up on press.

Since we're a web shop, and it takes a lot of paper before quality can be examined close enough to see these spots, there is a lot of waste and angry pressmen. It seems that no matter how much we scrutinize plates before and after processing, they show up on press 1st.

The problem is worse in cold weather, and I have also suspected humidity. Kodak has serviced the processor, our service provider has serviced the Screen, changed focus to pull it above the plate slightly (make it more forgiving).

Does anyone suspect plate quality problems, or is this machine maintenance related only? What do you use to control humidity?

 

[nemo]

Re: Cleaning hot spots on kodak thermal plates

Once again,
Hot spots on Magnus400 (fiber head) are only due to bad plate attachement to the drum.
If most of the plate looks good, the laser adjustment is fine - this machine has a static focus mechanism (no dynamic focus)
This can be caused by:
- missing load rollers (under the drum) - most common - they tend to come out during a flyoff. Newer machines have 1 piece load roller to avoid this.
- misaligned load roller or pressure adjusted too low
- low drum vacuum (clean holes, check drum vacuum pump)
- dirty drum
- if the hot spots are close to grippers - the grippers will need adjustment
- plate size too big (tail grippers will cause plate to bow out from drum)
- plate problem