Horizontal streaking

[Kaoticor]

Dear printplanneters,

We have a job that we only print once a year, a 4 color cover that is a solid brown. It is close to a 7504 brown if you had to put it in pantone... We get horizontal streaking (parallel to cylinders) consistently in the same place every time we print this job. I pulled individual color samples, and it seems you can see the streaking on all colors. We have other Lithrone 28's as well in different print shops who also print this same job, and the same problem appears on their samples. So we believe it is entirely mechanical, perhaps a design flaw or something of the sort.


Do you all have any other things you would try to better this problem? I think we have tried everything we can, but wanted to see if anyone had any comments before we close this. Thanks for your time,

-K

 

[Boneck]

Ink Charge... if you change your ink charge on the units... will the horizontal bar follow?

 

[Alois Senefelder]

Gear Streaks again !

Gear Streaks again !

Hello Kaoticor'


Read this thread and the PDF -

http://printplanet.com/forums/sheetfed-web-offset-discussion/21721-heidelberg-gto-gearmarks-printed-sheet


Regards, Alois

 

[D Ink Man]

If it's only one job, please try this.

May seem unorthodox, but it should eliminate the streaks.

1 Job:

Add 3-4% Silver to each process color.

Your streaks will be gone! D

 

[Kaoticor]

Ink Charge... if you change your ink charge on the units... will the horizontal bar follow?

I can turn the ductors off, and see no change (if that is what you are referring to)

Hello Kaoticor'


Read this thread and the PDF -

http://printplanet.com/forums/sheetfed-web-offset-discussion/21721-heidelberg-gto-gearmarks-printed-sheet


Regards, Alois

Alois,

On that thread I noticed you asked if the streaks were roughly half the distance around the circumference. I measure the streaks we have and they are roughly half the circumference. Is there any meaning to that, and if so, can you explain for me please?

Thanks,

-K

 

[Alois Senefelder]

Bearer Collision

Bearer Collision

Hello Kaoticor,

The following thread should prove to be an "interesting read" - pages 1 to 5 --

page 3 the relevant information - PDF - M.A.N. Bearer Collision 1+2

read all the other PDFs !

http://printplanet.com/forums/computer-plate/16499-registration-doopid-pressmen


Regards, Alois

 

[John Arneson]

can you post a picture?

 

[Green Printer]

This problem can be turned on and off quite easily. First check if there is any side movement in the water form. Any side play in the water form will cause this on all Komori's, Second if the copper water form rider is not oscillating is will cause this. if the stripe of the copper rider is less than 1 mm is will cause this, if any of the gears are loose in the dampner this will happen. Your water form to chrome stripe width can also be a cause set stripe between 4 to 5 mm to chrome and about 2 to 3 mm to plate. Water form durometer over 25 can also cause this.

Stripes also can be caused by ink forms moving when the vibrators change direction.

In the Komori almost any side play in any form ink or water can cause the stripes.

Another item make sure that all ink form rollers are set at about 4 mm to the vibrator and about 2.5 to 3 mm to the plate. If the rollers are set tighter to the plate the plate will be driving the roller and not the vibrator.

Last fountain solution can have a big play in this also. Any single one of these items can be a cause.

I have been running Komori's since 1992.

 

[Green Printer]

I can turn the ductors off, and see no change (if that is what you are referring to)


On that thread I noticed you asked if the streaks were roughly half the distance around the circumference. I measure the streaks we have and they are roughly half the circumference. Is there any meaning to that, and if so, can you explain for me please?

Thanks,

-K

The stripes will occur when the vibrators change direction. The vibrators change directions usually once per revolution. You can change when the vibrators change direction so that this could occur when most of the forms are in the plate gap.

 

[D Ink Man]

Remember gentlemen, "One Job". D

 

[Green Printer]

Remember gentlemen, "One Job". D

??????????????

 

[Al Ferrari]

Alois,

That thread is indeed an interesting read:

(http://printplanet.com/forums/computer-plate/16499-registration-doopid-pressmen)

Erik Nikkanen is right on target in his comments to you in that thread, and expresses what I have always thought of your pdfs.

You evidently don't realize that your practice of posting your pdfs as authoritative material, without dates (and often without sources), and without comments on your part actually does a disservice to print practitioners on this forum who are trying to understand their process and solve problems.

Al

 

[Alois Senefelder]

Streaks

Streaks

Gentlemen,


My answer to comments from Green Printer, in my usual form of a PDF !!


Regards, Alois

 

[Alois Senefelder]

Must, Truthful and Persuasive

Must, Truthful and Persuasive

Hello Al Ferrari,

I welcome a Acolyte of Erik also your comments, we have the free speech on this forum.

I share the same sentiments regarding your less than authoritative replys and knowledge,

you are welcome to correct any misinformation I have posted.


" To be persuasive we must be believable; to be believable we must be credible;

credible we must be TRUTHFUL" --- Edward R. Murrow


Regards, Alois

 

[D Ink Man]

??????????????

Read the entire thread Gareen Printer.

Then your "????????????" will be answered.

C- Ol' Mighty.

 

[Green Printer]

Alois's pdf in txt


Streaks–Cylinder Bearers and the Forces of Pressure


Hello Green Printer and fellow Lithographers,
We are not discussing Roller Streaks, you can set/reset the Inking Roller train forever and you will not eliminate these Press Gear/ Bounce Streaks that occur precisely half way around the cylinder circumference on the Plate/Blanket Cylinders.
The tell-tale signs are 2/ 3 streaks that appear on the blanket/plate cylinders and this is crucial at first also as bright marks on the cylinder bearers that coincide
Incorrect set rollers will not cause marks to appear on the cylinder bearers.
Until this problem is rectified, the Forces of Pressure will relentlessly destroy the case hardening of the steel cylinder bearers in those areas.
Regards, Alois

 

[Al Ferrari]

This does not inform us as to just what causes the streaks or the bright spots on the bearers, or what needs to be rectified. Is it the timing of cylinder lead edges meeting, or something else?

This sort of non information is what makes these pdfs useless.

I believe that presses with bronze cylinder bushings were more prone to this problem earlier in their productive life than presses with cylinders supported by preloaded tapered roller bearings. A cause identified and understood, and a solution implemented.

Al

 

[Alois Senefelder]

********

********

Hello Al,

My reply to your comments - again in PDF format,

 

[Alois Senefelder]

Part 2

Part 2

Al ,

One more non-information PDF , again you are welcome to correct any information I provide -With the right answers


Regards, Alois

 

[Al Ferrari]

From Alois' 2/10/13 2:36 PM post: "Obviously you didn’t read the PDF entitled Bearer Collision."

This point is well taken. That thread was quite long, and I may have missed more than just that one attachment. But that is precisely why attachments need some comment as to how they will serve the discussion.

"Obviously you dismiss the many PDFs I post as having little value," from the same post.

No Alois, you are wrong on this and are missing the point. Your pdfs in themselves often have very valuable content. But this is not always obvious because of the isolated way that you present them without any commentary of your own to amplify or give a context to their content. Almost none of the pdfs that you post originate as single page documents by their original authors, and you do not include their source for the interested PrintPlanet reader to pursue further. So my view of your practice in posting them is that you do a disservice not only to the readers of this forum, but also to the original authors of the works from which your pdfs are taken.

Your six year apprenticeship and other personal history, is not disrespected in the least. As I have stated, what I criticize is the specifics of you practice in posting your otherwise valuable pdfs.

Please see also my response to your Part 2" post.

Al