Bearer Bars

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Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Bearer Bars

Post by Gorilla Printer »

Hi All
We are having a problems with bounce.We are printing the biggest/widest solid I have ever seen. My press is gearless and CI.
We are printing on an already slit laminate that goes straight to the customer . There is no option of slitting afterwards

My boss has come up with what I feel to be a desperate idea of putting bearer bars on plate that will be printing on the CIC .I suppose he expects us to clean it when needed.He wants us to print at a higher speed as we are slowing press depending on the bounce.

Has anyone had to do this before?How did it go cleaning wise?

We are not getting missing ,but the speed with bounce causes miniature like flooding on the anilox which creates a darker patch on the solid print.

I am not liking the bearer bar idea as it would create more unnecessary work.I'm wondering if we should look at a particular blade for our chamber system. After all lack of good doctoring is the only visible problem being caused by the bounce,If you pay no attention to the thumping of the station.

Cheers
Gorilla
Last edited by Gorilla Printer on Mon Jun 28, 2021 11:50 am, edited 1 time in total.
iteachflexo
Posts: 48
Joined: Thu Aug 02, 2018 11:20 am

Re: Bearer Bars

Post by iteachflexo »

Adding bearers to the plate which will print directly on central impression drum is not a good idea, As the ink builds up on the drum, you will have to stop and scrape if off. Also, as the ink builds up on the drum, the ink will start flying off onto your subtrate. An option to consider is adding bearers directly on the drum with sticky back. Not sure if that is doable on your press or not. Would work better on an inline press. Another option is looking at the print cylinder size. Can you make the plate 2 around, 3 around, or more? Generally, the bigger the print cylinder, you have a better chance of eliminating the bounce.
longtimefan
Posts: 425
Joined: Sat Jun 13, 2015 1:10 pm

Re: Bearer Bars

Post by longtimefan »

Are you using a bridge (carriers) sleeve? Or is print sleeve right on mandrel? We have some bridges that are not made with carbon fiber material and we get bounce even with barer bars..

Try Diff sticky back?
Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Re: Bearer Bars

Post by Gorilla Printer »

@iteachflexo
I agree with your "bearers to plate" scenario example.

But was really impressed with your bearers to drum example!No one would have thought of that lol. And yes, I am that crazy to try it on my huge CIC if necessary.I see there could be a problem with them practically making the drum nip obsolete, but hey, high tensions hold register really well on this job.
You even gave me an idea of taping two strips of laminate to the drum and using bearer bars :eek:

About the option of having utilising different cylinder repeats. I believe we are, but will investigate further. This is a new job that has different repeats and widths. Yes, the more repeats on a cylinder, the significantly less bounce we are getting. Actually, we can just get the speed management is asking for.
Thanks for your input

@longtimefan
We have sleeves on mandrel.
And we can't change mounting tape as the big solids would look "pinholy" if we went softer.It could help with bounce ,but fine text would squash trying to alleviate pinholes . And potentially increase bounce due to more impression being required .
Thanks for your input

Update:So the bro and I decided on night shift to take the big solid out of station 6(8 colour press) and move it around to station two. Thinking , it was a dark blue and the other colours (red and a lighter blue) it usually printed over would be alright to print over the solid's reverse print. It worked. And we got the required speed. The problem is, it was one of the jobs that had more repeats and wasn't as wide, so gave minimal bounce compared to the two up big boy we have problems with. But hey, a gain is a gain. It did perform better around the front. We kept it to ourselves, hoping to "prove" it works over more runs.

A few days later on day shift we had the two up wide big boy.Again ,the bounce/backlash was causing minor flooding (chattering ?) .The manager -a printer wasn't happy.He was doing a moan job, practically crying how we'd lose the work as it wasn't financially viable if we couldn't maintain rate.It's amazing how Prima donnas crack when all they know doesn't work. They make up dumb shit like bearer bars that print on the drum lol.
So I spoke to the bro, and he said tell the boss about our switch around.As we were running good product and didn't want a major wash up ,the boss agreed to try moving the solid around to the front.We threw it in station 4.He was hesitant about the other colours printing over the top and bleed as another colour was printing in station 3.

Now this is where I'm supposed to tell you, that everything worked out ok.The colours were fine but the bounce and chatter was worse lol. Welcome to the joys of printing, guys. My manager quickly told us to switch everything back and run slower, lol.

So far I have learnt,kiss impression is a must , so is max air pressure on chamber for the solid and that this ain't over for me. Printing bearer bars on the drum is definitely a last resort.
Mind you, I have been thinking about placing solid slugs in line with the gaps in between solids and let them print on the drum. Could be an option and less of a clean-up than long lines of ink..

I'll keep thinking, networking and coming up with ideas with the bro.

Feel free to join us on our mission. I'll give you updates when something significant happens or when we come up with our fix

Keep the ideas coming, I am open to them all. It isn't over-"No print or press problem beats me" -that's my mantra

Cheers
Gorilla
just Andy
Posts: 85
Joined: Sun Sep 15, 2019 8:11 am

Re: Bearer Bars

Post by just Andy »

Hi Gorilla

I'd say printing on the drum is a bad idea:

If your job is a long run, then you'd spend more time washing the thick layer off the drum than actually printing. So you print full speed for one hour and spend the next our stopped, your effective average speed is going to be low.
If your job is a short run, then running slow will make a 1hr run into a 1.5-2hr run.

You also have a good point there re: nip roller, once the thickness of the ink on the drum is greater than the thickness of the substrate, the nip roller will be doing nothing for register.

A common solution is to separate the plates (of course you need a spare station for this). Run the type on one station and the solid on another.
Another thing with an older machine I've seen is that some stations are less stable than others. Switch the bouncing plate to the "good" station could help.
Carbon fiber mandrels and adaptors/carriers would also help; but that's not a quick fix.

If you really must print on the drum, I would suggest instead of putting bearers (full strips) you could put blocks in areas where the solids aren't printing. That way your sleeve is constantly in contact to the drum (reducing bounce) and also you "stagger" the amount print on the drum, thus increase the amount of time you can print on the drum until it gets too thick. And instead of blocks, mount 45' diagonal strips. But again, I don't think printing on the drum is the best idea.

I hope these help.
Andy
Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Re: Bearer Bars

Post by Gorilla Printer »

just Andy wrote:
If you really must print on the drum, I would suggest instead of putting bearers (full strips) you could put blocks in areas where the solids aren't printing. That way your sleeve is constantly in contact to the drum (reducing bounce) and also you "stagger" the amount print on the drum, thus increase the amount of time you can print on the drum until it gets too thick. And instead of blocks, mount 45' diagonal strips. But again, I don't think printing on the drum is the best idea.

I hope these help.
Andy
@just Andy
Mounting at 45 degree angles, although a great idea, is not possible as the product are cut into postbags so plate images need to be horizontal.

The "blocks" you were referring to I mentioned as "placing solid slugs in line with the gaps"."Great mind s think alike",huh :smile: That's what I am prepared to do should the need arise. But because I don't want to clean the drum, I am hoping to keep it to a bare minimum.

So far, the rate management wants is 120 mpm . But they are happy if I can run at 110 with limited banding.But if I am stuck @90mpm ,which I have been before,those blocks are going on.

We had our biggest solid the other day, and it was one up.Yes it wanted to bounce but I set inkers and impression that fine that we got to 110mpm where banding etc…was minimal.

This job is keeping me so honest, that I start running good product ,with minimal inkers /impression at 40mpm and increase speed in 5mpm increments looking for fine misses and adjusting . This ensures the least amount of pressure being placed on the station.

I feel we must try different sticky back as longtime fan suggested, proving we are using the optimal tape . We are using green 3M mounting tape at the moment, our next level softer is white. I'm wondering if there is an in between. It could be a quick experiment if we have the same solid plate proofed up on separate cylinders with different tapes.

Thanks for your input Andy

Gorilla
longtimefan
Posts: 425
Joined: Sat Jun 13, 2015 1:10 pm

Re: Bearer Bars

Post by longtimefan »

Can you Digicap nx plates. Maybe two sets of them
just Andy
Posts: 85
Joined: Sun Sep 15, 2019 8:11 am

Re: Bearer Bars

Post by just Andy »

Hi Gorilla

You seem a bit set into printing on the drum (hey if the boss approved it, try it out.). I still don't agree with it but I have thought about it a year or two ago.
What I meant regarding the 45 degree angle was mounting strips at a 45 angle, the ones that are intended to print on the drum. See my attached sketch (made on paint of course).

By mounting strips on on the inverse areas of the bands where you have the bounce, you will have continuous contact on the drum, reducing the bounce.
By using strips at a 45 degree angle, instead of full continuous bearer bars, it will take more time for successive layers to build up and become thicker than the substrate.

Regarding tape: remember the post I made regarding using a combination of mounting tapes. Perhaps that will work if you are also printing type or screens on the same plate.

But regarding printing on the drum bottom line is: if you have to stop frequently/take too long to clean it will not be worth running it faster just to stop again. This also doesn't account for any uneven wear on the nip roller, and just in general, creating a precedence to fix a solution like this. Although it is tempting.

Let us know what you end up doing
Andy
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Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Re: Bearer Bars

Post by Gorilla Printer »

Thanks for your clarification and PM Andy
Like any new job or material it takes time to work out the most effective way of getting a decent result.It usually comes from tweaks and experience.
I'm into introducing stuff in small increments .Remembering mounting strips on the cylinder would be an option but because I don't want to set a precedent will do it with no one else knowing apart from my senior printer.I envisage trying something like this .Pretty rough ,I know,but it's my first :smile:
plate.png
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I will update you guys on our progress.Most will depend on what my senior printer and manager can live with

Cheers

Gorilla
just Andy
Posts: 85
Joined: Sun Sep 15, 2019 8:11 am

Re: Bearer Bars

Post by just Andy »

Hi Gorilla

Small increments are good; it allows you to confirm whether the "experiment" is improving or not.

Those bands look good, so long as they overlap the image area but are not continuous it shouldn't build up a layer of ink too quickly on the drum.

Cheers
Andy
Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Re: Bearer Bars

Post by Gorilla Printer »

Hey @ just Andy
Thanks for your input and dm's, bro.
It seems to me I'm going to experiment with"bands" (bars) after our conversations.
When my senior printer asks why ,with a questioning look. I'm gonna tell him because some printers online suggested variances of it, and now I want to know .I also partially feel obligated :smile: . I can see him laugh and say "go for it bro"

The true test will be on the one up, big boy. It bounces the most. Problem is I have forgotten the cylinder size.The bro will remember.

Maybe the true way to test these bars out is set up job normally and then run at a speed where dark patches start forming from the bounce.Insert bars without resetting and see what happens at same speed or more,if there is improvement. This should show any difference.
If print is better, save settings and then try resetting with bars. Again, reaching optimal speed for quality and assessing.
While writing , I am liking this idea more and more. The experiment will not last long, and waste will be minimal.

I will give feedback, when we next hit job. Knowing my luck, we will be off shift when it gets run, and won't hit it for a few months. Which often happens

Cheers

Gorilla
longtimefan
Posts: 425
Joined: Sat Jun 13, 2015 1:10 pm

Re: Bearer Bars

Post by longtimefan »

Did you miss my advice?

Digicap plates!
Gorilla Printer
Posts: 317
Joined: Wed Oct 06, 2010 1:13 pm

Re: Bearer Bars

Post by Gorilla Printer »

longtimefan wrote:Did you miss my advice?

Digicap plates!
Hi longtimefan

No I didn't miss your post.
I also don't know what Digicap plates are and what they do.
It would help if you explained your comment.
Does it create a textured plate?

As operators, it is our job to first and foremost work with what we have.
Introducing different plates we've never heard of, for one particular job, sounds a bit extreme when different mounting tape hasn't been tried yet.
The problem is, the current tape prints the solid with fine text perfectly.

I'm thankful for the input and hope you get my point. We just can't throw everything at a problem. Our management doesn't work like that.We have to show everything we've done and then look at something different
Cheers

Gorilla
longtimefan
Posts: 425
Joined: Sat Jun 13, 2015 1:10 pm

Re: Bearer Bars

Post by longtimefan »

Its sort of textured yes. Almost like process dots but will print almost solid. I think having 2 would get the apperance you need. I used those on solid brown for mcdonalds coffee cups.
and I full get the need to try other stuff 1st..no issues..just wanted to make sure my post wasnt missed
Brian
Posts: 15
Joined: Tue Sep 25, 2007 4:26 pm

Re: Bearer Bars

Post by Brian »

We have had some success with ChannalBac to reduce bounce as an option for backing (pic attached). If possible, we will always run a potential "bouncer" in the most perpendicular deck to CI axis (decks 3 or 8 for me).
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