What's the Difference between Doubling and Slurring?

[Bryan]

Am I right that Doubling will always be basically Circumferential, and Sluring can be in all directions?

 

[Olle]

doubling can be lateral and diagonal also

 

[steveo]

Are you having a doubling issue? olle ' right it could be either.....

 

[print101]

Doubling is normally due to incorrect setting or worn grippers, allowing movement from unit to unit. Slurring is excessive squeezing of the halftone dot, this is normally movement between plate and blanket or blanket and paper. Both can be lateral and circumferential.

 

[exheidmech]

Doubling and Slurring are exaclty the same thing. When a pressman tells me his press is slurring or doubling, the troubleshooting process is exaclty the same. Terminology may be different in other countries. As noted in the previous post, print101 used the word slur do describe an increase in halftone dot size. I have never heard using the word "slur" to describe excessive dot gain here in the US. Even here in the US some people say slur and some say double, all the same thing.

 

[jetscreamer]

I've always believed was doubling was due to worn or incorrectly adjusted cylinder or transfer grippers, but i have seen it on a stream fed press when the sheet brushes and wheels are set to tight to the back of the sheet. Slurring usually occurs with incorrectly packed plate or blanket cylinders (baby you got to have the right squeeze).

 

[Bryan]

Thanx for the info; If in fact you have gone through, cleaned and adjusted all the grippers, and you know you have the right squeeze on the blanket, would you look at all to a mechanical "slop" between impression cylinder to blanket Cylinder within a unit?

 

[Bryan]

This problem is showing up on a 40" 6/C Akiyama.

 

[exheidmech]

The list of causes of slurring/doubling/blurring is as long as my arm. Causes can be bad blankets, incorrectly packed blankets, loose blankets, bad thrust bearings on any 1 cylinder, incorrectly timed grippers, worn pads, worn grippers, bad paper, incorrect infeed setup, bad side guides, incorrect set up of side guide, bad cam followers, smashed cylinder surface, incorrect allightment of main drive gears. Im sure I missed a few but the common ones are paper, blankets, feeder setup, and grippers. First thing I always do is throw in some 100# high quality long grain paper, this will at least eliminate paper.

 

[Bryan]

Pressman had the sequence in the middle 4 units. I suggested they move the units around to see if it makes a difference and isolates one tower over another.

 

[JOHNYPRINT]

Hi bryan
It does not matter what you call it,the answer is what you need to get to, exheidmech is on the button with his comments. I am at the same point as you are in that i am trying to resolve a double on a ROLAND 700. look back through the threads and it might help you to solve your problem. Check all the simple things first and to keep the boss happy with the most inexspensive, its a process of elimination. By the sounds of it you have cleaned and re-set grippers. take a pull with just deck/tower 1 in pressure, check print, if it's ok then it's occurring after deck 1. Then take another pull with decks 1 & 2 in pressure if unit 1& 2 print ok put 2& 3 in pressure ,keep going until the double/ slurr appears, then you can begin to assume where the double is occurring,keeping in mind that the double could be happening between more than one unit. It could be the impression grippers it could be on the transfer drum. keep in mind that setting the grippers with bad pads is pointless,(pads are more important than tips if you are working to a budget). make sure you have first made sure that your cam followers are ok, sometimes they may look and feel ok but under load they can cause a problem, the next thing to check(and this is the point where i am with my press) is the timing of the gripper transfer, if the impression cylinder is releasing the sheet before the next transfer drum has got control of the sheet(flying gripper transfer) there will be a slight movement and cause a double this could be caused by a worn cam. if you get to that point and still have a problem then you should seak the press manufacturers help. By the way how old is the press and how many impressions has it done, have the pads, tips , camfollowers been on the press for a long time, nothing lasts forever. Hope this may help.
regards johnyprint

 

[The Heidelberg Guy]

Doubling and Slurring are exaclty the same thing. When a pressman tells me his press is slurring or doubling, the troubleshooting process is exaclty the same. Terminology may be different in other countries. As noted in the previous post, print101 used the word slur do describe an increase in halftone dot size. I have never heard using the word "slur" to describe excessive dot gain here in the US. Even here in the US some people say slur and some say double, all the same thing.

+1!!!

 

[madjock]

Having seen Heidelberg guys setting grippers I wouldn't recommend trying it unless you have all the right tools and know exactly what you are doing!

 

[pressman57]

First thing I always do is throw in some 100# high quality long grain paper, this will at least eliminate paper.

Truer words have never been spoken. You can see exactly when the good stock is gone.....thing of beauty, thing of beauty, hideous crap, hideous crap.....etc.

 

[rossio]

The list of causes of slurring/doubling/blurring is as long as my arm. Causes can be bad blankets, incorrectly packed blankets, loose blankets, bad thrust bearings on any 1 cylinder, incorrectly timed grippers, worn pads, worn grippers, bad paper, incorrect infeed setup, bad side guides, incorrect set up of side guide, bad cam followers, smashed cylinder surface, incorrect allightment of main drive gears. Im sure I missed a few but the common ones are paper, blankets, feeder setup, and grippers. First thing I always do is throw in some 100# high quality long grain paper, this will at least eliminate paper.

... differs pro´s from laymen

Sorry but I´m an old printer...first think I´ve learned was to learn how it works.

 

[InkSlinger]

I think Johnnyprint has a pretty good take on this one, I've found that on Akiyamas, those cylinder cam followers can have a great effect here. I think that there is a lot of pressure on them and can tend to go bad sooner than one might expect even when greased regularly. Check them for surface cracks and excess play (laterally as well as around) and replace all on the cylinder if any are found bad. Proceed unit by unit (as johnnyprint described) until the problem is located, take the load off of the follower, and check them for slop, smoothness of roll, surface cracks etc. Assuming, of course, that they are properly lubricated.

Then, depending on their (the followers) previous condition grippers may need to be reset...

I've always felt that slur and doubling are just different levels of the same problems, where doubling is when it gets really bad...

Best of Luck...

 

[bad78]

Am I right that Doubling will always be basically Circumferential, and Sluring can be in all directions?
Slurring is when the halftone dots shift from round to eliptical shape. 3 kind of sluring : circumferential, lateral and diagonal. Cause : the interuption between image reciver ( from plate to blanket ) or between image transfer ( blanket to paper ). Doubling is when the halftone dot seem double. Cause by worn impression cylinder gripper, untight plate and blanket.

 

[tonyc]

I don't believe slur and doubling are the same thing and identifying the difference will help to find the fault quicker. A double is where the printed dot does not register in exactly the same position, think of 2 overlapping circles.
A slur is a drag of a dot which results in a comets tail on the dot either vertically or horizontally. Example - This can happen when the plate cylinder cylinder and blanket are turning at different speeds due to the blanket being over packed.
Checking the dot on a colour bar patch through a illuminated magnifier (x50) will enable a quick identification. A star target will show a horizontal or vertical figure 8 for slur. A double is normally shown as a diaganol number 8 but can be horizontal if the double is even across the sheet.

 

[John Van Hoorn]

Doubling and Slurring are exaclty the same thing. When a pressman tells me his press is slurring or doubling, the troubleshooting process is exaclty the same. Terminology may be different in other countries. As noted in the previous post, print101 used the word slur do describe an increase in halftone dot size. I have never heard using the word "slur" to describe excessive dot gain here in the US. Even here in the US some people say slur and some say double, all the same thing.

We have a winner!

 

[amp080]

Hi
We have a GTO52-P age 2002 and it is producing of what i think is slurring.
We had tested the press by printing unit by unit and the first unit always matches spot on; while the second unit is slightly shifting from head to tail of sheet in a synchronised manner of about 1 mm shift each sheet up and down
The slurring we are getting on the second unit is caused by ink migration from the first unit of the press.
We have also noticed that the pair of grippers located on the storage drum is receiving the sheet positioned differently in terms of gripper byte

Does anyone have an idea what is causing the issue?