registration

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registration

Postby Leadpress » Wed Sep 11, 2019 2:02 pm

OK, I have a new one. Even though I've been doing this a long time, I've only been running film for about 3 years. I have so much movement it's not even funny. I don't have chill rolls, and I'm using UV inks. My first color always walks in one direction, so it's predictable and I usually beat it before it gets there. However, I'm double bumping my first color for opacity, the second image is slightly smaller than the first to avoid peeking out, but they still peek out due to movement. I've always been told not to use nips on film, so I never use them. I tried using the central nip yesterday, and all it did was loosen my material to the point of everything out of whack. Sometimes if I engage my infeed nip, It goes through the torque roller and also causes the material to loosen up and unravel itself at the nip. As I'm running 7 colors on the film, I can see where I'm constantly going back and forth with register; why won't it hold steady? any Ideas???? Frank, Gorilla, dustin, fuzz, barb; Helpppp!!!!
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Re: registration

Postby Fuzz » Wed Sep 11, 2019 3:00 pm

If you don't use nips, than you are relying on unwind brake and rewind tension to pull consistently. Doesn't seem right to me. I think you need to contain and stabilize the tension between nips. Film, unsupported or supported can be fickle and some stretch more than others. See if there is another type of material that can be used to minimize stretch. Here we had a terrible time with rego on a supported film. We switched vendors and it works great.
Guess you never said which way the movement is. Across the web or with the web? I just assumed.
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Re: registration

Postby Frank Burgos » Wed Sep 11, 2019 3:14 pm

There are times when we have to do tricks to make things worse, and it may very well be that you have a situation where you just can't run nips. I get that. However, ideally,, you should run nips.

It may mean that all rollers need to be clean, nips and bearing i good condition and tensions throughout the press optimized to avoid issues, but that's the ideal situation. You're probably lifting nips because there's a problem with the press and you're compensating by allowing the film to slip.

By the way: I was training some guys and they were running at 100 fpm. I asked them why and they said "because ______ told us so and we've always done it this way." I cranked it up to 400.

Have a great day!
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Re: registration

Postby longtimefan » Wed Sep 11, 2019 6:44 pm

Ci press?


Check Nip pressure on drum maybe out of whack or to hard.

Never in 30 years of running ci presses mostly film some.1 mil.. Ever ran wo Nip on drum
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Re: registration

Postby Gorilla Printer » Thu Sep 12, 2019 12:30 am

Leadpress wrote:OK, I have a new one. Even though I've been doing this a long time, I've only been running film for about 3 years. I have so much movement it's not even funny. I don't have chill rolls, and I'm using UV inks. My first color always walks in one direction, so it's predictable and I usually beat it before it gets there. However, I'm double bumping my first color for opacity, the second image is slightly smaller than the first to avoid peeking out, but they still peek out due to movement. I've always been told not to use nips on film, so I never use them. I tried using the central nip yesterday, and all it did was loosen my material to the point of everything out of whack. Sometimes if I engage my infeed nip, It goes through the torque roller and also causes the material to loosen up and unravel itself at the nip. As I'm running 7 colors on the film, I can see where I'm constantly going back and forth with register; why won't it hold steady? any Ideas???? Frank, Gorilla, dustin, fuzz, barb; Helpppp!!!!


Hi Leadpress
Could you help us out with more info please.Remember we are doing this blind.Pics would help too.So here are some questions I have.Is this a CI press.How old is it?Is it gearless.Does yuur drum nip have seperate smooth and knurled rollers.Do you have problems with all film or just this particular one.What is it made of,its characteristics,how thick is it.Yeah is the film stretchy or rigid (i'm assuing stretchy.Is it slippery?Do you use all nips for another film job that runs fine and if so what is the materail,how thick and the tensions aroun the press?I'm assuming heat isn't a factor between stations and in tunnel as with uv inks you guys use light to cure ink.Sorry I don't know U.V ink printing.But anyway more info please sir you are talking to a blind man lol.
For now I'll leave you with this ,running without nips is BS and whoever told you that doean't know what they're are talking about.Nip points are for control .Now I have accidently run a job with a my CI drum nip open and it held register I was lucky it was perfect tension.But the person that told you to do that is just a beginner in my books.Because thats what beginners do,give up,instead of maintaining control of web and finding the sweet spot.Otherwise there is a machine issue, so fix it.
Anyway sorry for any typos or grammar issues as I'm about to leave for a 12 hour shift in a job I love!Flexo for life!Arghhhhhhhhhhhhhhhhh! :smile: :smile: :smile:
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Re: registration

Postby Frank Burgos » Thu Sep 12, 2019 9:17 am

You a gorilla, brugh
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Re: registration

Postby Leadpress » Thu Sep 12, 2019 5:03 pm

Sorry guys! I haven't figured out how to upload photos. I will soon though. Fuzz, it's moving along the web. not side to side. It's not a CI press; it's an inline 8 color Nilpeter, servo; gearless sleeves. I was told not to use nips, but guess what? I did a thorough maintenance on all nips and used all three, and my register is alot better. It just jumps a beat here and there. I'll have 8 dead on images and one way off????? Then 10 or 20 on and on or two off? However, better than before. Thanks all of you guys; you guys are swell, like peter brady used to say!
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Re: registration

Postby Frank Burgos » Fri Sep 13, 2019 10:10 am

Leadpress,

Immediately below the window in which you compose a message is a tab labeled "Upload Attachment." Click on the tab, browse to the image file and click "Add the file."

Have a great weekend!
Attachments
Inkeduploadimage_LI.jpg
Uploading an image
Inkeduploadimage_LI.jpg (129.62 KiB) Viewed 115 times
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Re: registration

Postby Buck from N.C. » Fri Sep 13, 2019 12:01 pm

Try cutting down the intensity of the UV lamps.
Also, run the press as fast as possible without inks not curing!
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Re: registration

Postby wdustin1 » Mon Sep 16, 2019 9:31 am

I'm with the others on this, always use the nips, it's the only way to maintain a tight register, you have to play with the pressures and tensions on film of course. Heat is always our biggest enemy, we run the press high speed, and turn the blowers on the u.v. cooling system up higher to help control some heat. play with pressures of the nip rollers and play with tensions to keep the web as tight as possible, i have always had the best luck with keeping the infeed nip pressure higher than the outfeed, for no good known reason!
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Re: registration

Postby Leadpress » Mon Sep 16, 2019 11:00 am

Thanks Frank, Dustin and Buck; those are all great tips. I will try all of them and I'm sure I'll get great results. I will let you know how it goes. Thanks
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Re: registration

Postby just Andy » Mon Sep 16, 2019 12:26 pm

Hi Leadpress

We ran a few weeks on a thick paper and then afterwards we ran on a thin film. This was a repeat job (same material, same tension settings) the register was moving around (side and long) and the rewind was also shaky even with the edge guide on. We used a piece of paper as a feeler gauge and could certainly tell the nips were worn down, almost exactly the same width of the paper. The short term solution is to simply increase the pressure. If this is indeed the cause of your problem, a rubber engineer would be able to re-grind the nip rollers to be even again. It also helps if you have a higher shore hardness nip for more abrasive substrates and a soft one for stretchable substrates.
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Re: registration

Postby longtimefan » Tue Sep 17, 2019 3:50 am

just Andy wrote:Hi Leadpress

We ran a few weeks on a thick paper and then afterwards we ran on a thin film. This was a repeat job (same material, same tension settings) the register was moving around (side and long) and the rewind was also shaky even with the edge guide on. We used a piece of paper as a feeler gauge and could certainly tell the nips were worn down, almost exactly the same width of the paper. The short term solution is to simply increase the pressure. If this is indeed the cause of your problem, a rubber engineer would be able to re-grind the nip rollers to be even again. It also helps if you have a higher shore hardness nip for more abrasive substrates and a soft one for stretchable substrates.

In a pinch...since a smaller mark Andy.. Wrap the rubber nips with thick paper or tyvek? Maybe helps if nips are to wore down
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