Hi, new to this site.
I have been in the business for 22 years,and been a pressman for about 16,or so.
About 9 months ago we get a new UV installed. I just have to ask,is UV printing this problematic for everybody??? My last press,a 105 8 color(conventional printing) ate the work UP! This press is the complete opposite. The problem? Bad ink adhereance and vectoring issues on plastics, severe toning issues on uncoated paper, feedback on the pan rollers,blankets wearing out after 10,00 impressions,rubber ink train rollers only lasting a month or 2. The list goes on and on. Don't get me wrong,I'm not whining,it's just that it is RARE that we can put a job on,make ready,then run. In other words,if I got paid by the sheet,my family would be going hungry right now. It's just kind of frustrating,that's all.
My company has only been running UV for about 3 years now,so there was/is a learning curve I suppose. I am just curious if this is the norm though?
Regarding your rollers: Are you running with EPDM or Hybrid rubber. (If you have conventional rubber they will be destroyed in short order).
I have found that EPDM lasts well but can become distorted over time especially as far as the ink-ductors are concerned. Hybrid rollers seem to work very well even in a dedicated U.V. environment, they seem to have better dimensional stability than the EPDM.
Do you set your rollers a little lighter than "standard specs"? 0.5mm lighter to the oscillators and the plate might help. Make sure your fountain concentrate and alc replacement chemistry is U.V. compatible.
I have used the conti - air EBONY blanket with some success. However you cannot expect them (or any other brand) to last as long as they do in a conventional environment. After two months or so the vehicle in the ink and the U.V. solvent will cause embossing and render the blankets unusable, I do not know whether or not you can remove the blankets from the press in good time and "rest" them. I think perhaps this might work but have some doubts.
Does your press have any "ink-mist" control on it. Even if you have "blowers" over the ink train I would try to make sure that they are working 100%. U.V. ink always 'mists' like crazy and keeping the fountain solution out of the ink as much as possible will help with the "catch-up" and "scumming"
I have found that the ink water balance is much more difficult when running U.V. and found it helpful to figure out where the minimum ink-water positon actually is.
Are you running interdeck dryer heads? I have found it helpful to cut the blanket packings to just a little outside the sheet size other wise spurious reflections from the dryer heads can dry the ink outside the sheet edges on the blankets and impression cylinders. This eventually leads to dampening and other problems.
Otherwise U.V. is easier than conventional to get along with.
As far as printing on plastic is concerned all I can say is that heat is a problem (for fit)
from unit to unit the plastic becomes distorted by the heat. I found out that U.v. lamps emit large ammounts of I.R. radiation and this is the source of the heat. The lamps can be fitted with special filters to clean out the I.R. emissions and the lamps run cooler as a result. I think this is called "cold U.V."
If you are running 4~6 colours and U.V. coat run an interdeck on the last printing unit to dry the ink before you coat it, plus if you have IR lamps in the delivery then turn one IR lamp on to low power as close to the coater as you can you will find that the smoothness and gloss of the U.V. coating is improved.
Hope this helps
Thanks for the reply.
We are running Chameleon rollers right now,but are going to try true UV rollers next time. Chunks of rubber just come off of them,and they swell up bad.
We are on our 3rd type of blanket now. Can't remember the vendor,but they are called "Ruby's" these are the best we've had yet,but we're luckey if we get 3 days out of them. Old blankets we had to change every job or two,because of "memory",or bad print quality on uncoated stocks. I can't believe you are getting 2 months out of yours!
Yes,we have a vacuum/filter system on the units to help with misting,these don't do much.We ended up turning rollers temps down on longer runs,which seemed to help.
It is our SOP to cut packings to sheet size on stock thinner than .012". Also depends on run length.
We do have a external filtering system for our fountain water,this helps keep it clean. We can now change our water every week or 2. Before the aftermarket filter system was installed,every day!
The fit problems on plastic is a major time killer for us. I will run UV lamps with just enough energy to cure the ink. But on longer runs,at about the 15-20K impression point,the built up heat in the press throws the fit out to the point that we have to stop,and get new vectored plates. Most of our plastic jobs are 8 colors,so this is very expensive,and then re-make readying the fit is a production killer. Some of our longer runs need to be vectored again at the 50K mark or so.
Interesting comment about the "cold lamps",I'll have to inquire about these. There is liquid coolent going through our lamps,but I don't know if that is the same as what you mentioned.
Thanks!
One of my own issues is that I was always anal about running a minimum ink/water balance. This helps out alot on plastics. Running paper though,just seems like I have to keep bringing water up to clean up the toning. Where as on a conventional press a few percent increase in water would do the trick,on the UV press it seems more like 15-20%,on paper. It just goes against my grain to do this! This then causes curing issues,feedback on pan rollers,ect. We have tried a few different fountain solutions and doses,but still trying to dial it in.
Welcome to UV printing, although it should not be all that bad it will be frustrating to the conventional printer. Hopefully the press is equiped with UV materials such as, blankets, rollers and proper chemicals. The inks are more difficult to work with and just about everything you mentioned I have run into at some degree. I ran UV for 15 years and supervised Co-Cure or hybrid for the past 5 years. Hybrid I find even more difficult.
UV - Blankets, I like DYC K-110's, Ink we had great luck with Superior, but also had on site people who knew how to handle ink problems. Etch and 10% Alcohol worked better than the new Etch and Sub's.
Rollers, you can't run conventional rollers they will be destroyed. I am not sure what is on the market for straight UV at this time. We used EPDM rubber, it was OK but not great.
Ken
Albert, UV ink cures instantly (or it SHOULD!) under the UV lamps. So printing on plastics and uncoated stocks,there is very little,if any,dry time.
UV gloss coatings on coated paper also gives a very high gloss level,as compared to our aqueous coatings,and dries instantly,so no need to worry about blocking/setoff like you would running a conventional gloss varnish.
As you can see from my posts,it has it's challenges though.
Fireplug55,we do have UV blankets,fountain solutions/sub running. Though the Chameleon rollers are not working out for us. We just put a few new rollers in a couple printing units last week,and are going to see how these hold up. I will have to check if they are EPDM or not,I didn't ask,because I'm still learning here.
We run Toyo ink,and have an in house lab. They have been working with us on our inks,and it seems things are overall getting better,but Toyo is not too crazy about our current fountain solution.
We have changed so many variables,so quickly,that it is hard to keep track of what is working,and what is not. For example,the fountain solution/sub was changed to what we are running now,then only 1 week later we started running a reformulated version of our paper ink. In the meantime,prepress decides to change to a different type of plate! We also changed our blanket supplier about 1 month ago. Then you factor in things like I think fountain solution A ran better,the other two shifts press operators think B ran better. I think only one change at a time,try it out for awhile,then get input from all 3 shifts is the way to go. But in the real world,when the clock is ticking,things are not always done that way.
Just glad to hear that someone else had similar problems. I was just wondering if this is common,or are things just SNAFU at my shop,because I don't really have contact with any other UV printers.
Thanks!
Thanks Gordo.
Actually the "ruby's" that we are running now we do send back. I'm not sure if they recondition the existing surface,or resurface them all together. We started doing this because of the huge expense of the blankets we go through.
I will point this blanket out to my manager though for price comparisons.
Drake67, You have got to slow down or you will have no idea what works and what does not.
I can tell you the DYC K-100 blankets are very good, but like any UV blanket I have used memory will get to them sooner or later.
Toyo ink, you can keep them I have had Zero success with them. Best inks I have used are Sun Chemical and Flint, but was not crazy about flint it was kind of a backup.
It is great you have Toyo working with you, take suggestions from them about the fountain Sol. They need a water that works with their ink and if it does not work it becomes their problem, push that issue at that point.
Ink and water is always an issue, it is a constant battle. Your dot will inprorove with a change to the K-110 blankets. If you are still not happy with the results, prepress can always help.
You will find the more ink you move the eaiser it is to control. Put take off bars on the sheet if you can on any light coverage printing.
Ken, catch you again later have to go.
Quote:
Originally Posted by 67drake
Albert, UV ink cures instantly (or it SHOULD!) under the UV lamps. So printing on plastics and uncoated stocks,there is very little,if any,dry time.
UV gloss coatings on coated paper also gives a very high gloss level,as compared to our aqueous coatings,and dries instantly,so no need to worry about blocking/setoff like you would running a conventional gloss varnish.
As you can see from my posts,it has it's challenges though.
Fireplug55,we do have UV blankets,fountain solutions/sub running. Though the Chameleon rollers are not working out for us. We just put a few new rollers in a couple printing units last week,and are going to see how these hold up. I will have to check if they are EPDM or not,I didn't ask,because I'm still learning here.
We run Toyo ink,and have an in house lab. They have been working with us on our inks,and it seems things are overall getting better,but Toyo is not too crazy about our current fountain solution.
We have changed so many variables,so quickly,that it is hard to keep track of what is working,and what is not. For example,the fountain solution/sub was changed to what we are running now,then only 1 week later we started running a reformulated version of our paper ink. In the meantime,prepress decides to change to a different type of plate! We also changed our blanket supplier about 1 month ago. Then you factor in things like I think fountain solution A ran better,the other two shifts press operators think B ran better. I think only one change at a time,try it out for awhile,then get input from all 3 shifts is the way to go. But in the real world,when the clock is ticking,things are not always done that way.
Just glad to hear that someone else had similar problems. I was just wondering if this is common,or are things just SNAFU at my shop,because I don't really have contact with any other UV printers.
Thanks!
Any UV pressmen out there? Help!
Linear Mode
