Komori ink density differs gripper to tail

[Slice]

We have two 2007 Komori LSX a 29" and a 40". Both of these presses show different ink density from gripper to tail. When we run multiple-up of the same image and it is cut down the shade differs from pile to pile. the 40" runs conventional inks, the 29" runs UV inks. Someone said to have the operator adjust roller timing. I don't know what he is talking about and I am not an operator. Can someone explain in layman's language what is happening?

Thanks

Slice.

 

[Cornishpastythighs]

http://printplanet.com/forums/sheetfed-web-offset-discussion/20397-ink-flow-roller-setting

A discussion from Printplanet about this very subject

 

[Foster]

On our LS 640 we have to adujust the oscillation. In the PQC-touch panel ours in under Inker clutch/phase screen. Where we engage and disengage the unit not printing. If yours is the same, You should see a button for home position and start. Are current home position is 400 mm. You can change that to change the oscillation. That is the set value button. You pick the unit you want to change, then increase or decrease the set value. When you decrease the set value, it take the density more to the tail of the sheet. Increase set value you get more density to the gripper. For example i need unit 3 to print more ink too the tail, i select unit 3 take set value down to say 290 mm then hit start button. You will see it change to 290 mm. Then you can always hit home position then start to go back to 400 mm. Hope this helps. Best answer i got.

 

[The G-man]

Hello. I ran a 2007 Lithrone. That adjustment was on the gear side of the press. You have to open the door to the unit and remove a small panel to get to the adjustment. What this does is time when the ductor roller charges the inking rollers. Most pressman shoot for the charge to be when the plate cylinder gap comes around. Refer to your manual for details.

 

[Deleted member 16349]

We have two 2007 Komori LSX a 29" and a 40". Both of these presses show different ink density from gripper to tail. When we run multiple-up of the same image and it is cut down the shade differs from pile to pile. the 40" runs conventional inks, the 29" runs UV inks. Someone said to have the operator adjust roller timing. I don't know what he is talking about and I am not an operator. Can someone explain in layman's language what is happening?

Thanks

Slice.

This condition seems to be common. Timing of the ductor can affect this and also timing of the oscillators can affect this depending on the image being printed.

Of course it is press design related and it means that one can not get an accurate profile of how the press prints since it prints differently in different areas.

Trying to adjust timing of the ductor and the oscillation might help if you can move towards a more neutral condition.

Also a possible action can be to open some of the contact points between rollers in the roller train to change the way ink films are stored on rollers and their paths to the plate.

Good luck.

 

[Dan Roll]

I agree with all of the above roller related approaches, but would like to add if your ink has too high a pigment load, you will see a lessening of density from lead to tail.

 

[Green Printer]

Go here. This eliminates the problems. I am having this installed on press next year.

Welcome to Amerikal

 

[Deleted member 16349]

Go here. This eliminates the problems. I am having this installed on press next year.

Welcome to Amerikal

Interesting. Looking forward to your results and comments after you get started.

On one unit for testing or for all print units?

 

[Green Printer]

Interesting. Looking forward to your results and comments after you get started.

On one unit for testing or for all print units?

All Units. These have been out in the field for close to 20 years in Japan's can industry. There are installs in the US.

 

[Deleted member 16349]

All Units. These have been out in the field for close to 20 years in Japan's can industry. There are installs in the US.

I think it would also be good for Dry Offset for printing containers. But it would have to have much narrower segments.

Good luck.