Mark Andy P3 Silver Stock Oscillation

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Mark Andy P3 Silver Stock Oscillation

Postby Saturnia » Thu Feb 13, 2020 9:20 pm

Greetings,

Thank you for accepting me into your community. I've been involved in the flexo industry and have been working as a flexo-press operator for about two years now. Most of my skills and knowledge were acquired from more experienced colleagues as well as my own experiences. My flagship press is a Mark Andy P3 Performance Series that I've lovingly named Irene. Each time I go home for the night, I tell her goodnight. Everything has been going well and I can run jobs efficiently at very high speeds (750fpm is the top speed on this particular press). However, there is one material in particular that gives me a headache. For certain labels, we use a #40 silver stock with a brown liner (not sure if that is the standard name!). I am a person who prides themselves in delivering quality in a timely manner. The problem that I am experiencing with the silver stock (brown liner) is that, for some peculiar reason, it oscillates throughout the press ever so slightly, causing the print to be a tad misaligned. This drives me batty.

I've tried things like increasing tension and running at slower speeds. Nothing I've tried seems to work. I was hoping that someone could shed some light and help me understand the reason why it happens and how to counteract it. I figured that if I increased the tension, it would stop it from moving up and down like it does. Unfortunately, I am doing this "blindly" and have no real clue as to how much tension the stock could take or if tension is the issue in the first place. Could someone please help me out?

Sincerely,
Saturnia

Postscriptum,
Is the a way to determine how much tension a particular stock can take or is designed for?
Saturnia
 
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Re: Mark Andy P3 Silver Stock Oscillation

Postby longtimefan » Fri Feb 14, 2020 1:03 am

Not sure how to determine tension strength.

Have you looked at your nip points? Can you adjust? Are they worn? Bearings okay?

You could try to run tape along the edge of rollers or a herringbone design
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Re: Mark Andy P3 Silver Stock Oscillation

Postby Fuzz » Fri Feb 14, 2020 10:24 am

First thing I would do is make certain that you are using web guide on both sides of the material. (I've seen many times operators only using one side) I like longtimefans thought about worn nips, especially if the material happens to be narrower than you normally run. "S" wrap any rollers you can. I'll ask our operators how they would handle this issue. Good luck.
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Re: Mark Andy P3 Silver Stock Oscillation

Postby Jonathanburbank » Mon Feb 17, 2020 1:01 am

A higher tension isn't going to help unless the stretch is accounted for. Young's Modulus needs to be calculated for the press and the material. Without this the smoothness and ease of printing in register and proper side-lay are very difficult.
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Re: Mark Andy P3 Silver Stock Oscillation

Postby Fuzz » Mon Feb 17, 2020 6:10 pm

You do a lot of Youngs Modulus calculating before running a job? I'd guess not, and if so, please share.
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Re: Mark Andy P3 Silver Stock Oscillation

Postby Saturnia » Mon Feb 17, 2020 7:51 pm

Salut tout le monde,

Thank you all for the fast responses. Here's a follow up;

Today, I had the chance to try a few of the suggestions provided in here. We're currently running jobs that require brown-back silver lining. I've provided a link at the bottom that will direct you guys to a short YouTube clip of the effects as seen on my monitor. The video appears sideways, but it's the right orientation. It's just that the image is flipped 90º clockwise on screen, though I'd imagine you guys already knew this :]

Fuzz wrote:First thing I would do is make certain that you are using web guide on both sides of the material. (I've seen many times operators only using one side) I like longtimefans thought about worn nips, especially if the material happens to be narrower than you normally run. "S" wrap any rollers you can. I'll ask our operators how they would handle this issue. Good luck.


I was always told that the second sensor is not necessary, though logic dictates that a second sensor would provide the guiding system with more data/accuracy. I'll be sure to use the second sensor henceforth. Thank you for the suggestion.

longtimefan wrote:Have you looked at your nip points? Can you adjust? Are they worn? Bearings okay? You could try to run tape along the edge of rollers or a herringbone design


Irene's nips are well. The rollers are brand new and I'd like to believe that I am using an adequate amount of pressure. I've not tried running tape on the rollers as I feel that it would be very time consuming for such a massive press. We also do not have any herringbone rollers (I assume these are rollers, yes?), though that sounds very interesting. My boss will certainly be herring about this idea tomorrow, waka waka.

Jonathanburbank wrote:A higher tension isn't going to help unless the stretch is accounted for. Young's Modulus needs to be calculated for the press and the material. Without this the smoothness and ease of printing in register and proper side-lay are very difficult.


I've tried determining Young's Modulus a couple of weeks ago to no avail. I figured that the problem lies in inadequate tension which is indeed leaving too much slack through the press. Woefully, we don't have a proper way of finding out in our shop. Determined to solve this issue, I began blindly increasing the tension (between nip rollers) in small increments but decided against it out of fear of snapping my web. I see these numbers printed on the stock rolls with a pound sign next to them (#60 as an example) and figured those values could help me determine the proper amount of tension required to rid myself of slack/stretch. I was told this was something else entirely so I dropped it. The intense frustration I felt is the sole reason why I ended up on this forum :smile: Thank you.

As mentioned above, I made a short video of the effects of the oscillation. I pride myself in delivering quality labels at ludicrous speeds. Perhaps I should use the Schwartz. I'm still learning the trade and these type of annoyances are a major hindrance to my progress. Here is the clip I made earlier today; https://www.youtube.com/watch?v=r2jdZdo ... e=youtu.be

Any help will be greatly appreciated. Vielen Dank :]
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Re: Mark Andy P3 Silver Stock Oscillation

Postby Gorilla Printer » Mon Feb 17, 2020 11:27 pm

Saturnia wrote:As mentioned above, I made a short video of the effects of the oscillation. I pride myself in delivering quality labels at ludicrous speeds. Perhaps I should use the Schwartz. I'm still learning the trade and these type of annoyances are a major hindrance to my progress. Here is the clip I made earlier today; https://www.youtube.com/watch?v=r2jdZdo ... e=youtu.be

Any help will be greatly appreciated. Vielen Dank :]


Hi Saturnia
I hear your annoyance. Problems in printing we don't like as they are a hindrance to producing. But when I have one that I struggle with, that's gold because I'm about to learn/overcome something. And that's what I love the most. These annoyances are the most important part of developing as a printer. So relax and enjoy the ride. Anytime I go to work and learn something new, has been a great day. Getting the production target is good, we either get it , pass it or don't-it is what it is.

OK, now with the problem. I have no understanding or experience with MarkAndy's as I have only run CI's.I watched the video and was intrigued. What I saw happening would typically be on our last station. The colour wandering up and down. This would be to do with too much tension for the material. The material would very stretchy/springy than normal. And the thinner the guage, the worse it gets. The material is practically going through the press springing back on itself.
In this situation I sort of let the material show me it's the tension it wants by lowering them so there is practically no stretch. but before doing this I turn the heaters right down to minimise it's effect to the substrate.If you can maybe have the heaters off but the blowers on for the interim just to complete the tension test. The edges of the substrate will be at an even floppiness through the press. Have an open mind, go down with the tensions as low as you can for the material,(practically so much so you are risking having it wrap around a roller. This is your starting point -the most minimal tension you can get. You need to have a bit of courage as sometimes you have to throw the rulebook to the side I've run my press on 2/3/4/kgs tension for unwind/infeed/outfeed nip points which was unheard of. But now it's a S.O.C for the new material everyone was struggling to maintain registration and press speed with.Why?Because everyone didn't want to go lower than the lowest tension they had seen on the press (Press Standard)
Anyway start from there and see how the registration behaves don't worry about creases/print at this point -you need to prove if you can get the register holding better.
That's my 2 cents worth from a guy definitely on the outside looking in. If I'm way off track -my apologies, but I couldn't help wanting to contribute :-)

Good Luck!



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Re: Mark Andy P3 Silver Stock Oscillation

Postby longtimefan » Tue Feb 18, 2020 12:11 am

Herringbone can be achieved using tape.

Start in center of roller and spiral it towards the end..do same on other side
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