Ink density - anilox or formula impact?

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Re: Ink density - anilox or formula impact?

Postby barb » Thu Oct 19, 2017 10:25 am

Gory, technician from our anilox supplier was here today.

I'm still shocked but also disappointed/ashamed because up until now I just refused to believe that our aniloxes were the main problem. I always compared the 5 year old ones that are at our other machine - but never did occured to me that there is so much difference in maintenance depending on what liniature are they.

As it turns out, the wear on them caused the enormous 40% drop in volume. :(

Well then, remember kids - never make conclusions without experts by your side!

Inkmans are still coming over so I'll just make sure we get the best formula we can from what we can gain with these aniloxes until we repair or replace them...
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Thu Oct 19, 2017 10:33 am

That's great, Barb.

I recommend that you guys get a 400x coaxially-lighted microscope and allow the operators and other folks that handle aniloxes look at the anilox surfaces with the scope on a regular, frequent basis. When pulling from storage, before cleaning, after cleaning, when storing, when problems arise, when the rolls are just sitting there are they're bored, etc. Wear or cell plugging that is enough to affect volume is apparent. Operators will learn to correlate cell appearance/condition with performance. The insights gained are among the most important an operator can possess, in my opinion.

Frank
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Re: Ink density - anilox or formula impact?

Postby barb » Thu Oct 19, 2017 1:44 pm

Hi Frank, thanks for the advice. Yup, right after they left we started talking about buying one of those microscopes :smile:

This was a huge eye-opening for everyone included in pressroom so I believe in the future we will pay way more attention to maintenance and check-ups.

I completely agree with your statement, once you know for sure what you're working with it's easier to solve any issue that comes up.
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Thu Oct 19, 2017 3:09 pm

You're welcome!
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Re: Ink density - anilox or formula impact?

Postby barb » Fri Oct 20, 2017 1:24 pm

Well Frank, if it weren't for this forum or your videos on youtube, I wouldn't have know at least the half of things I know right now, so no welcoming needed :wink:

Now, after sleeping over and drinking few beers after the initial shock the only thing left to do is to decide where do you go aftewards. What's the smartest thing to do. Since we're a smaller company we absolutely can't afford to change our aniloxes every one to two years so we're definately considering to down it even to 360 or 340 lcm. But what volume would be appropriate? How do you even calculate what's best for your machine? Suppliers seem to be a bit uninterested - they recommend their volume but with no explanation whatsoever - so far.
I'm still a newbie at this point so my main concern is how will our press behave regarding our previous prints if we go for example from 450 l/cm, 4,5 cm3/m2, to 360 l/cm, 5-6 cm3/m2.

Oh man, two years ago I barely knew how the flexo printing plate looks, and here we are now, I have to figure out and decide what aniloxes and volumes would be suitable for our needs. :(
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Mon Oct 23, 2017 8:24 am

Hi Barb,

I'm so glad you found help here.

I want to add that if you associate your ink formulas with aniloxes, by serial number, in your documentation, including job ticket, over time, even as the aniloxes wear out, your formulas will be gradually adjusted to compensate for the decrease in volume and you will see fewer instances of adjusting color and swapping out aniloxes for color strength.

At most companies I visit, operators are free to swap aniloxes to adjust strength. This is poor practice. Anilox volumes are optimized for reasons more important than only color strength. Swapping aniloxes just to adjust for color strength is symptomatic of a lack of understanding of the anilox's role and guaranteed to cause headaches, wasted time and wasted materials.

An environment where an operator is free to swap, without any protocols mitigating the decision and the result, is out of control.
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Re: Ink density - anilox or formula impact?

Postby barb » Fri Dec 22, 2017 4:29 am

Hi guys,

just a small update regarding my issues...

With formulas for 450 aniloxes (approx. 65% base pigments in all cmyk inks) we got following densities:

C - 1,52 (450 - 1,40)
M - 1,44 (450 - 1,19)
Y - 1,28 (450 - 1,19)
K - 1,43 (450 - 1,20)

using new 360 aniloxes.
Which is not bad, but honestly, I did expect a little more. But this also could be because they were repaired and not brand new.

Nevertheless, we dropped a bit down the % of base pigments just to leave us some room for future adjustments. Minimum percentages on Asahi plates still look great and I hope this will work for some longer time than those 450s.

I also made a target density sheet with all parameters defined so we'll keep on testing every two months to see how aniloxes and ink behaves.
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Re: Ink density - anilox or formula impact?

Postby Buck from N.C. » Fri Dec 22, 2017 8:20 am

Sorry if I step on any toes but, sometimes asking an anilox supplier to do an inventory is like asking a fox to guard the henhouse. :smile:
The last one on my press showed the 1000 line I use for process black was at 52%. I was still reading 1.6-1.7 on density! C'mon now! :smile: :smile: :smile:
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Re: Ink density - anilox or formula impact?

Postby barb » Mon Jul 02, 2018 3:30 pm

Hi guys, back to the topic!

Is there a way to determine at what point should you change your doctor blades?

We have a new set of aniloxes but we still have the old practice for doctor blades - not changing them until they start causing unsolvable problems and I'm not sure if this is a good practice.

I'm afraid we could damage the new aniloxes also with excessive usage and pressure applied to blades as they start to wear off.
We have ceramic aniloxes and metal blades. As I have noticed, most of the time the blades are changed after half a million meters.

Thank you upfront!
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Tue Jul 03, 2018 8:44 am

Hi Barb,

The blades should meter cleanly, with the surface of the anilox appearing uniformly matt or dull. Shine indicates that ink is hydroplaning past the blade.

If the blade is lamella-tipped, you probably don't want to wear the lamella completely off. Operators should also not over-tighten the blade adjustments.

It's difficult to go just by meters printed. Aniloxes and inks differ in their abrasiveness. The trick is to learn to identify when the blade has worn to the point of requiring replacement.

Frank
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Re: Ink density - anilox or formula impact?

Postby barb » Tue Jul 03, 2018 11:15 am

Thank you Frank!

I also watched your video on that topic - helps a lot when someone explains it in simple terms!

Alright so if I understand properly, if I notice anilox to get shiny and the pressure is already close to max that can be a good indication that the lamella has worn off?
barb
 
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Tue Jul 03, 2018 11:20 am

Could be, Barb. I see it all the time, everywhere I go.
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Re: Ink density - anilox or formula impact?

Postby barb » Tue Jul 03, 2018 3:14 pm

I can only imagine.

One more question if I may - do you approve of the practice where operators change the blades pressure in order to achieve the target density?
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Re: Ink density - anilox or formula impact?

Postby Frank Burgos » Tue Jul 03, 2018 3:24 pm

[quote="barb"]I can only imagine.

One more question if I may - do you approve of the practice where operators change the blades pressure in order to achieve the target density?[/quote]

Absolutely and emphatically not! That's precisely what I'm talking about. They get the blade ink to hydroplane under the blade by applying too much pressure to the blade. I get that folks want to get the job done, but it had better be with that understanding; a temporary and terrible cheat. It's variable and just not the best way to go.
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Re: Ink density - anilox or formula impact?

Postby barb » Tue Jul 03, 2018 3:42 pm

Yeah I was expecting that kind of an answer, just needed confirmation. Thank you!

PS.
This reminded me of one time when I was inspecting dot gain issues on the print and I tell the operator that he can achieve the desired target if he tunes in the anilox/plate pressure and the response was (dead serious): "what are you crazy, I already work hard with matching the densities with doctor blades, now you want me to **** around with pressures too?!"
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