Type of nip on wide web ci

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Re: Type of nip on wide web ci

Postby just Andy » Mon Jul 27, 2020 2:39 am

Hi longtimefan

This is not going to solve the problem (and certainly not a solution, because it doesn't crack the problem head-on) but just from a general design perspective, why is the half-tone red knocked out for the type? For easier registration in general it should not have the knocked out spaces, and let the black over-print the red half-tone. It would also eliminate the visible clip around in general. Depending on the anilox used, the black would not easily show a halftone redness underneath.

Anyway, the problem looks to be like it could be station specific. Which I would agree with lavoie. But if you say the tech had a look at it and looks good from the programming/settings, did the tech also look at supply current of each motor?

Mechanically, I've once had the registration slot for the sleeve come loose and would also move the register. Nothing ol' superglue couldn't fix though.

Alternatively, I've had a similar issue when running a thick, rough paper for the whole week then the next job moved onto thin, slippery film. All the nip points were worn down. Increasing your nip roller's pressure substantially may temporarily help the problem. But as Gorilla said, do a paper-feeler gauge test, and best do that before ordering a new/grinding down the nip.

Cheers
Andy
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Re: Type of nip on wide web ci

Postby longtimefan » Mon Jul 27, 2020 8:21 am

The graphics people a still learning is my only answer why it was knocked out

I’ve tried high nip pressure, low, almost none. Tried a bow roller before nip .. tried big unwind tensions and low.

Tried extra impressions, dryer pulled out, flow adjusted
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Re: Type of nip on wide web ci

Postby Gorilla Printer » Mon Jul 27, 2020 9:33 am

Is it gearless?
What station is black in?
What station is red in?
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Re: Type of nip on wide web ci

Postby just Andy » Mon Jul 27, 2020 10:08 am

Hi longtimefan

This is a shot in the dark here but after re-watching the video, it appears to be a clean and perfect but random longitudinal register movement.

> If it were material/nip roller/tension/dryer it would move the side/latitudinal register as well. This isn't the case.
> If it were the cylinder/tape/plate, it would be off-register but consistently off. This isn't it either.
This clean random movement is to do with some sort of play, as lavoie mentions the bearing could be worn. It could also be some sort of play on the mandrel/motor or (unlikely) a fault on the CI drum (e.g. timing belt). I still feel it looks like a faulty cylinder or register slot that is loose because of personal recency in mind. But this is easily ruled out if it occurs on other sleeves with other adapters/carrier sleeves.

What I would say is that the register movement is minimal and depending on your quality standard, it is still commercially acceptable. It is akin to a pretty decent but older geared press. With that, I would continue running as is and let the operators report the common variables; e.g. "it always happens on the repeat/this station/this webbing mode/etc...
Before you spending more time and resources on bringing in electrical technicians/buying new nip rollers/calibrating load cells/etc..., it would be better to gain some sort of direction as to what the root cause is. A random guess at this stage would cost more than an educated guess with some evidence to direct you.

Also, when you mentioned adjusting the dryers, I do hope you marked the original positions.

Cheers
Andy
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Re: Type of nip on wide web ci

Postby longtimefan » Mon Jul 27, 2020 1:57 pm

Gearless...we have 1/32 acceptable register play
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Re: Type of nip on wide web ci

Postby longtimefan » Mon Jul 27, 2020 1:59 pm

Gorilla Printer wrote:Is it gearless?
What station is black in?
What station is red in?

10 color press

Black in 9 red 4
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Re: Type of nip on wide web ci

Postby lavoie » Fri Jul 31, 2020 3:50 am

For the time being, I would have the trap increased on the images run in those two decks. 1/32 is not much to play with.

Did the tech remove the servo motor? It looks like there may be play in the plate drive gears on those decks. It does look very much like a geared press in the video.
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Re: Type of nip on wide web ci

Postby longtimefan » Fri Jul 31, 2020 6:05 am

lavoie wrote:For the time being, I would have the trap increased on the images run in those two decks. 1/32 is not much to play with.

Did the tech remove the servo motor? It looks like there may be play in the plate drive gears on those decks. It does look very much like a geared press in the video.


I don't think he removed the servo. No gears.
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Re: Type of nip on wide web ci

Postby Fuzz » Fri Jul 31, 2020 9:26 am

Can you run the two colors closer together or right next to each other. Instead of 9 and 4, how about 4 and 5 or 8 and 9.
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Re: Type of nip on wide web ci

Postby longtimefan » Fri Jul 31, 2020 11:34 am

Fuzz wrote:Can you run the two colors closer together or right next to each other. Instead of 9 and 4, how about 4 and 5 or 8 and 9.


Probably could..

Thing was is that we were told deck 9 (black) the register was fixed
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Re: Type of nip on wide web ci

Postby Gorilla Printer » Sat Aug 01, 2020 12:19 am

longtimefan wrote:Gearless...we have 1/32 acceptable register play


On our gearless presses that consistent movement would not be acceptable and mine is a 20-year-old machine that was originally geared. That's a reason why the industry moved to gearless.


For two techs to have visited with one finding nothing wrong with the servo settings looks to me that the process of elimination hasn't worked. And something has been overlooked.If our maintenance guys called in outside techs that found nothing and didn't fix the problem,there would be "please explains" happening

When we have a problem the operator tries to fix it . Then the Supervisor will help. But before maintenance is called in, we have to make sure it is a fault in the machine and not something we have inadvertently done.

Depending on the fault our maintenance guys go through their process of elimination.

Cleaning the drum and nip rollers doesn't mean they are working correctly.

Do you have a maintenance team there?

I'd start from scratch and make sure every part to do with registration is checked.

Infeed,CI and out feed nips are checked they are working properly.Even the air supply to them.Then eliminate them of the list.
Well it looks like servos are to be eliminated too.
Could whatever that holds advance/retard register on the decks be checked that there is no movement/play?

Movement on video looks like it happens every 10 to 15 seconds.

Are the tension drives working OK .Are the tension rollers working correctly?
Does the press have draw mode and tension mode.Are they set on the one mode throughout the press?

If all of the above is good I'd start looking at the stations
Because you have varying degrees of movement on stations, I'm inclined to look at mandrels and cylinders ,checking their TIR next. My "clue" that could be wrong is the black registration movement wasn't perfectly even, leading me to believe something could be out of round.

Gorilla
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Re: Type of nip on wide web ci

Postby lavoie » Sat Aug 01, 2020 8:19 pm

longtimefan wrote:
lavoie wrote:For the time being, I would have the trap increased on the images run in those two decks. 1/32 is not much to play with.

Did the tech remove the servo motor? It looks like there may be play in the plate drive gears on those decks. It does look very much like a geared press in the video.


I don't think he removed the servo. No gears.


The servo motor drives a gear that either directly or indirectly drives the shaft that the sleeves go on. It looks to me like you have gear lash from a worn gear somewhere.
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Re: Type of nip on wide web ci

Postby Gorilla Printer » Sat Aug 01, 2020 9:42 pm

lavoie wrote:
The servo motor drives a gear that either directly or indirectly drives the shaft that the sleeves go on. It looks to me like you have gear lash from a worn gear somewhere.


Hi lavoie
I didn't know servo motors have gears.But the registration movement I saw looked like a gear.I thought of it no further when longtime mentioned the press was gearless.
So it can seem quite plausible that if the servo motor gear is worn,it would mimic the same registration movement you'd see from a worn gear against the bull gear.
I think you are onto something and feel those motor gears need to be checked.That could also be why there is different movements on different stations?

Cheers
Gorilla
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