Komori 40" creasing..

[GazKL440]

We are having a few minor probs with our 40" Komori...

Firstly, longitudinal creasing (grip to tail), always on the drive side of the press, and only on the light stock that we use a lot of(80gsm 'velvet'). It is not terribly bad, not enought to pull up the job, but irritating nonetheless!! This stock comes from china or taiwan or whatever, and we use 2 containers per month of it, and i have noticed that there seems to be a fair amount of variance in the quality of this paper. each skid is a lottery as to how much curl it carries and how well sheeted it is, but it does print very well....aside from this issue!! There is no creasing on slightly heavier stocks, but on the velvet it does become more evident with increased run speed but seems ok around 11,000s/hr. I have tried running very little pressure on the brush wheels, and run my smoothers at an absolute minimum pressure(if at all!!)

Secondly, and this may be related to the first, we get a slightly inconsistent image "run out" in the back corners, again evident on lighter stocks but no problem on 150gsm up. The 1st unit image is the biggest culprit with the rest fitting to within half a line of each other, but unit 1 being black tends to show up. Taking pressure off the smoothers used to make a difference to this, but now it would seem that on the first pass not much helps. Generally on the 2nd pass this issue is improved almost 100%. I need a new metering roller on the 1st unit as its pretty sad, and i think that the lack of water control on that side (its more evident on the operater's side) does not help, but am concerned that it may require re-setting of grippers through the press and have an engineer check the cam-followers etc.

The press is a Komori L440 (yr2000) with about 110million impressions on it..

Any suggestions would be much appreciated

 

[Jimbo]

This might sound simple but is your guide spring too tight? Maybe try using a lighter spring.

 

[GazKL440]

i assume your talking about the side lay roller spring?? Yeah i run it as light as possible, have found too much pressure will give you a slight mis-register, and varying the pressure on the spring doesn't seem to affect the problem on this stock...

 

[Laxmi Kant Kuthiala]

try checking the grain direction of the paper. the grain should run along the gripper edge, which means that the paper should be long grain on the machine. Short grain paper will tend to crease if there is a moisture imbalance between the paper and the pressroom. You can notice this imbalance if the stock starts getting wavey, and it will always be on the cross grain. The wavey side is not what you want in your grippers.

 

[John Arneson]

with 110 mil imps on your press I would say it is most likely time to reset your swing arm gripper and possibly replace the cam follower.

 

[Servicetech]

Start with the swing arm, It needs to be gone through. the pads may be worn and the pad bar may no longer be straight.

 

[QualityPrint]

I have actually seen this happen on newer komoris when the blowers between the units are set too high. This may help you but I am unsure as to the setup of the 2000 komoris.

 

[GazKL440]

Put a new set of rollers in one unit and a new metering roller in first unit, allowing me to cut a lot of water and ink out of unit one to achieve balance, and this did improve the situation a little....and certainly improved the print result Still getting a little creasing, and some run in of the image from grip to tail, but both the run in and creasing are virtually non-existent on 2nd pass. I'm leaning towards getting the swing arm looked at and the grippers throughout the press, as whilst its not the end of the world it is certainly irritating having to split the difference to get a job to an acceptable level.

QualityPrint: The blowers have not been touched since the press was installed, apart from cleaning of filters. So i dont think that they are the prob as this issue has gradually arisen over last few months.

Quick question: Will the height of the cover lay, and the opening depth of the swing arm grippers possibly cause this?? What would be the recommended opening setting of the swing arm grippers be for light stock??

 

[QualityPrint]

A setting of 3 on the front lay is correct for a paper .012 thick. We have been told that 1= .004 thickness in paper. So 2=.008 and so on and so forth.

Also, you may want to check/ clean all the grippers on the impression cylinders as well as the transfers.

 

[GazKL440]

Just a footnote on this issue... This issue continued for a little while, and after having to open the swing arm grippers to accomodate the extra thickness on 350gsm board, i swapped back to a full size 720x1020 100gsm job, and the fit and creasing were absolutely shocking.

A quick re-think on the set up and i realised that i had not re-set the swing arm grippers. Setting them to 3 saw a vast improvement, and coming down a little more saw the creasing completely gone and the fit come in to within half a dot in the back corners, close enough that i could split the difference and run the job without concern, and it only improved as the press warmed up over the course of the run.

The next job on was run on the lightweight 80gsm matt art, and another slight tweak saw this job 100% all over, and without the creasing issue was able to properly crank up the press and get some work done, averaging over 10k s/hr.... very happy

Thank you to all for your suggestions, especially QualityPrint for hitting the nail on the head

 

[pierreborg761]

Dear Sir
We are looking for anti smudge film for impression cylinders before delivery, can anyone help us from where we can source this possibly from EUROPE.
thanks for your help