Identify these press marks?

[jackcardc]

Can someone identify these press marks? The pressmen are calling them chatter marks. I do not think they are chatter marks but marks coming from a chrome roller for whatever reason. We have monitored the plates for a period of time and also had the Fuji reps. in and there are no indications the marks are coming from the plates. After a few thousand sheets on press they show up and you can see them on the plate. They run in the press direction. They appear to be scratched into the plate and very visible. KBA sheetfed 64” six units plus coating.

 

[Cornishpastythighs]

I could only open a very small picture of the file you attached and I am assuming its those black looking marks going across the sheet. They don't look like chatter marks to me. They almost appear to be one on the inking forms rollers or dampening roller is causing the issue. Do the space between the marks equal the diameter of any of the rollers in your press, that would be the first thing I would check for. Is the issue on only one print unit and is it the same print unit all the time as this would rule out a plate issue.

 

[The01Printer]

Those marks (well the one I seen from the little bit of pic that loaded) look just like a problem I was having on a small sheetfed for a while and finally figured out that pin bar for holding the plate was barely hitting the water and form rollers and somehow causing them to scratch the plate after 2000 or so. I tapped it down with hammer and never had the problem again! That may not be it at all since this was just a small press, see if the marks line up with anything on your plate mounting system or blanket and impression cylinder.

 

[Kaoticor]

Hello, those marks are very similar to what we get from time to time here. If it is the same problem, we traced it back to contaminated bits in our water system. From the oscillation movement, it ends up creating a pattern that looks like small "tracks" that eventually end up scratching the plate (these "tracks" can be seen on the chrome roller). The pattern we see on the chrome roller looks like this

: : : : : : : : : : : : : : : : :


We have seen this in every unit at some time or another. When it comes up, we do a thorough cleaning of the dampening system on whichever unit is affected, such as:

Washdown the unit and clean the water form very well.
Clean the chrome roller with a chrome roller cleaner.
Wipe down metering roller thoroughly.
If you catch it early enough, you can save the plate, but if not, you have to make a new plate.

I'm not 100% familiar with the KBA's but wanted to share this in case you are getting something along the same line. Hope it all works out!

-K

 

[gig0]

I can't help you but can tell you print stuff for White Castle. BELLY BOMBS!

 

[Lukew]

We get this from time to time. I always trace it back to being a contaminant usually a tiny dry ink particle on the metering roller & sometimes water form.
I remember we had one brand of ink that always did it, not sure it it was from poorly ground pigments or just tiny flecks of dried ink in the fresh tins.

 

[blindpig]

Have seen those marks on my Komori 540 SP. It seems to be caused by metal or other trash, on or even cut into the water forms. We also get that same pattern when a bad plate hang,(Tall ends up sticking up in a sharp point), cuts the water form in same pattern as you chatter. New water form takes care of the problem. Ps. We also get a pattern like that from our Fuji plate machines, when crap builds up on processor rollers, only tracks show up in random colors.

 

[jackcardc]

We see them predominately in the dark units especially Black and dark spot colors. In the ligher colors they blend in with the print and are not easily seen. I am leaning towards Kaoticor’s comments as that’s what I have guessed by talking to a few of the pressmen. As of now it’s easier for the less experienced press crew to ask for new plates for a quick fix without trouble shooting. Also we noticed they show more often after there is a change in the fountain solution. Also the pic was cropped to show just the tics. Didn’t want to have an oversize photo. Thanks for the responses.

 

[rsands]

Is it just down that area or covering more of the sheet?

 

[jackcardc]

It is in random areas across the sheet. Never in the same area. Always in the press direction and CTP direction from lead edge to trail edge of sheet. When we pull the plates from press, we see a small shiny mark on the plate as if it was scratched. We do not see this on plate prior to going to press.

 

[buckeye]

...we see a small shiny mark on the plate as if it was scratched. We do not see this on plate prior to going to press.

That would DEFINITELY be a Pre-Press/plate problem and not a pressroom problem in our shop.

Erik

 

[Alois Senefelder]

Visible

Visible

Hello jackcardc,

Question - are these marks visible on paper within a 50/100 makeready sheets ?



Regards, Alois

 

[Drewstre]

That would DEFINITELY be a Pre-Press/plate problem and not a pressroom problem in our shop.

Erik

-----
Um, how ya figure? He said "When we pull the plates from press, we see a small shiny mark on the plate as if it was scratched. We do not see this on plate prior to going to press." I can't see how that's a pre-press issue. Sounds mechanical to me.

 

[buckeye]

Drewstre,

I was being facetious. It clearly sounds like a press/mechanical issue to me, but in our shop, our pressroom has a bad habit of thinking otherwise.

Erik

 

[chad.trent]

Drewstre,

I was being facetious. It clearly sounds like a press/mechanical issue to me, but in our shop, our pressroom has a bad habit of thinking otherwise.

Erik

That's not limited to just your shop...

 

[buckeye]

That's not limited to just your shop...

Oh the stories I could tell, but won't, so as to not hi-jack this thread.

Erik

 

[jackcardc]

They seem to appear out of no where, no set amount of sheets or run time. The Press crew cleans blankets and after start up they will re appear after 3000 sheets.

 

[jackcardc]

We are doing our checks before going to press as in cleaning the VLF’s drum roller, as we know it picks up metal plate shavings occasionally. However we thought we should see any marks caused by this. Plates are inspected just for these marks and nothing can be seen. One thought was maybe the anodize coating of the plate has a flaw and the fountain solution further enhances the problem. Also the plates are processed 90 degrees from the way the plate is imaged and run on press.

 

[bgfx]

can you process the plate in the other direction left to right instead of lead to tail

 

[HPC]

This is a shot in the dark but we've had a similar problem, way different press, turned out to be the plate guard, one pressman would really slam that thing in place as a result we were getting marked plates only on his shift. A loose bracket holding the guard was the cause, not to mention the pressman.