interesting issue with impression

[Albert Noel]

we've been having issues with our ink for a while now and just recently switched inks. we decided to re-fingerprint the press in the process, to make a long story short, i found that unit 5s impression cylinder has a very solid imprint from the blanket. dark enough to read, shiney so on and so forth. only thing is, it's only about 6 to 8 inches up from the gripper.

packing is correct, blanket is correct, all is torqued properly and the unit is printing correctly.

pre-mature impression? impression not disengaging on time? theres no setting that i know of to change impression timing.
anyone seen this before?

i've attached photos and a video link.

MAN Roland 305

 

[rich apollo]

Not really sure what your images were showing. But on two Roland 305's and a Roland Rekord we had a dark stripe that would happen 3-4 inches from the gripper. Magenta showed it really badly, of course. Never could get those bastards to lay smooth solids. They'd print extremely sharp, but wouldn't lay solids for anything.

 

[67drake]

He is printing image onto his backcylinder,so the prees is staying on impressoin after the last sheet had cleared the unit.
We have had this on our Heidelbergs on a few occasions. I don't know offhand what the cause was. I can check with my mechanic when I get to work today.

 

[Paultheprinter]

He is printing image onto his backcylinder,so the prees is staying on impressoin after the last sheet had cleared the unit.
We have had this on our Heidelbergs on a few occasions. I don't know offhand what the cause was. I can check with my mechanic when I get to work today.

The issue on heldebergs is the impression rams, the seals in the pistons go so there is a delay on coming into and of preassure, on heidelbergs you can get the seals renewed, i have had this a few times now and it starts with a 1inch band of impression on the back cylinder and gradually gets worse.

Good luck Paul

 

[Albert Noel]

Not really sure what your images were showing. But on two Roland 305's and a Roland Rekord we had a dark stripe that would happen 3-4 inches from the gripper. Magenta showed it really badly, of course. Never could get those bastards to lay smooth solids. They'd print extremely sharp, but wouldn't lay solids for anything.

i can get this 305 to lay a decent solid but nothing impressive.
yeah, 67drake, thats mostly what i was thinking. i was looking at it again today and it's definitly late coming off. like paultheprinter said, it may be the impression rams. i'll have a look at them tomorrow and see if anything is visibly wrong.

 

[67drake]

Albert,
I got to work today and went to talk to our in house mechanic,he just started here,and had previously worked as a field mechanic for Manrolland for a number of years,so figured this would be right up his alley. I found out he has the week off deer hunting though.
Anyway,I talked to our other inhouse mechanic,but he came to us from Heidelberg,so that's all he knows. He said along the lines of Paul. He said if your rolland is anything like the Heidelberg,you will have pneumatics to drop on impression,and another to force off impression. If your pneumatics for pushing off is getting lazy,it will stay on for a short period too long. He said to check if it has a solenoid for actuating the "off",the Heidelbergs have a button to push on the solenoid to manually operate it.See if it does anything when pushed. Also check for airleaks in the lines to and from it. But,as I said,this is assuming it it similar to Heidelbergs set up.

 

[Albert Noel]

Albert,
I got to work today and went to talk to our in house mechanic,he just started here,and had previously worked as a field mechanic for Manrolland for a number of years,so figured this would be right up his alley. I found out he has the week off deer hunting though.
Anyway,I talked to our other inhouse mechanic,but he came to us from Heidelberg,so that's all he knows. He said along the lines of Paul. He said if your rolland is anything like the Heidelberg,you will have pneumatics to drop on impression,and another to force off impression. If your pneumatics for pushing off is getting lazy,it will stay on for a short period too long. He said to check if it has a solenoid for actuating the "off",the Heidelbergs have a button to push on the solenoid to manually operate it.See if it does anything when pushed. Also check for airleaks in the lines to and from it. But,as I said,this is assuming it it similar to Heidelbergs set up.

i think it's similar to the heidelberg like you mention, with solenoids actuating the pnumatics. i've got a button for manually throwing on and off the impression at each unit, but nothing on the solenoids themselves. i'll have to dig into it today when i get to work.

i wish we had an in house mechanic. sadly we only have 3 presses, so we get to be our own mechanics . thanks i appreciate the time you spent asking about it.

 

[67drake]

No problem.
Yes we are luckey. Our old in house mechanic just got promoted to a position to maintain the whole building campus,so we hired a guy from Manrolland to take his old position,so we have 2 knowledgeable guys around.

 

[Albert Noel]

i did a breif check today and it throws on and off cleanly. doesnt seem to be a delay though i know there is one.

great, service call time

 

[jbeniston]

Albert
The impression off/on is in two stages. First against the plate and then to the impression cylinder and the reverse sequence coming off pressure. There is a delay coming off impression, the air cylinders might be getting lazy or something has happened so the signal is n't getting there in time.
It can be fixed.
JB

 

[Albert Noel]

heh well, getting my manager on board for a service call is not working too well.

i've been complaining about alot of little things over the last few weeks and i think he's a little overwhelmed by me wanting so many little things fixed at once, now add this cylinder issue to the mix...

also, thanks for passing along our many communications. pierre. (i believe is his name) i spoke to him at printplanet last saturday and mentioned he would be coming by to check us out.

 

[jbeniston]

Thanks for the response. I hope Pierre does a good job there, show him the photographs if you don't mind
JB

 

[Albert Noel]

well, this issue seems to have completly solved itself. no image on the impression cylinder at all after 25,000+ sheets and multiple make-readies

 

[jbeniston]

That doesn't usually happen until the mechanic shows up on site. Keep your eye on it, becqause something isn't right. Let Pierre have a copy of your photographs anyway.

 

[67drake]

Albert,I know the problem seems to have gone away,but I talked to our mechanic this AM before I left work,first time I've seen him since he got back.
He pretty much said what our Heidelberg mechanic told me. Most likely a solenoid going bad,or the piston leaking.
But he did say to check a few more things. He said that if your overall press air pressure is to low,it has to show up somewhere first. It can cause weird little problems like this. He said your pressure gauge on your press should be around 8-10 bar,and it is adjustable. If it is lower than this turn the pressure up the next time your problem happens to see if it goes away. He also said he has seen where water in the airlines can cause things like this to happen. Not too often,but easy to check. He said make sure your water trap in your airline is drained so that it does not get into your lines.
Hope this helps.

 

[Albert Noel]

havent seen this issue so far since i've posted, buti'll check it.

it's usually set and running at around 90-100 psi (about 7 bar) but it's been like this since the press was installed. maybe i'll turn it up a little and see what happens.

thanks again for speaking to your mechanic. i appreciate it