Heidelberg PM 74 2005 2 COLOUR

[Alistair Tinsley]

Hi everyone and thank you all for your help.
I am unable to find what is causing the problem on print.Two marks same place everytime that go across the sheet from on end of cylinder to the other as shown in Photo.
Have checked ink rollers,but it's same place every time so cannot be them.
Checked blanket, tried new blanket,new packing,makes not difference.Never no mark on plate,plate is fine,can see a little shade on blanket though but all feels good.The next cylinder is fine as well and nothing on transfer cylinder, blue net replaced etc.
Any pointers appreciated.
Thank you
I changed to other unit and it was fine as photos show.

 

[Beguin]

Hello dear sir, have you checked the touch of the four ink touch rollers against the plate and the touch of the dampening touch roller against the plate. There must be ink and dampening rollers or the contact with the plate is too much. Thank you very much.

 

[Alistair Tinsley]

I have checked these all yes.
All look as they should.
If it was the touch rollers though why would it always be same spot?
It bound to move ,this is exactly same place every pass.
Also there is no sign of the problem on the plate.
Thank you for reply.
Any other suggestions

 

[asem alsafady]

Dear sir
Does the problem appear one unit only?
Is the first attached photos you have sent one solid colour job?
Do these lines appear only horizontally at the gripper edge area?
Can you explain the second and third attached photos?

 

[Alistair Tinsley]

Thank you for reply.
First attached photo solid block.
It is mainly the 2 marks at gripper edge i am concerned about.
Yes problem only on one unit.
Photo with arrow the bad unit as you can see with the marks.
These go horizontal all way across sheet at gripper edge 60mm in for first mark 80mm for second mark.
Photo with tick is the good unit which cleans up and prints perfect.
Really strange,used to print great.
Blankets packing all new.
What do you think ?
Thanks

 

[Phil Patey]

Thank you for reply.
First attached photo solid block.
It is mainly the 2 marks at gripper edge i am concerned about.
Yes problem only on one unit.
Photo with arrow the bad unit as you can see with the marks.
These go horizontal all way across sheet at gripper edge 60mm in for first mark 80mm for second mark.
Photo with tick is the good unit which cleans up and prints perfect.
Really strange,used to print great.
Blankets packing all new.
What do you think ?
Thanks

Hi Alistair,
This looks like a repeat mark.
It could be caused by the Dampening forme (plate) roller sliding as it touches the front edge of the plate.
This slip can cause a horizontal repeat mark across the sheet.
You must make sure that the dampening plate (forme) roller has more pressure to the matt chrome oscillator roller than to the plate.
Ie; when setting the Plate dampening roller, it should have a stripe of 5mm to the plate and 6mm to the Matt Chrome roller. OR,
You can set it to 4mm to the plate, and 5mm to the Matt Chrome.
The pressure to the Matt Chrome should always be stronger than the pressure to the plate.
Otherwise, If you still have the same problem you can change the timing of the oscillation, this can help.
Instructions are in the operators manual, it's easy to do and can't do any damage (unless you leave the bolt loose).
Just take a photo of the setting before you move it in case you have to return to the original setting.
Good luck.
Cheers Phil

 

[Alistair Tinsley]

Hi Alistair,
This looks like a repeat mark.
It could be caused by the Dampening forme (plate) roller sliding as it touches the front edge of the plate.
This slip can cause a horizontal repeat mark across the sheet.
You must make sure that the dampening plate (forme) roller has more pressure to the matt chrome oscillator roller than to the plate.
Ie; when setting the Plate dampening roller, it should have a stripe of 5mm to the plate and 6mm to the Matt Chrome roller. OR,
You can set it to 4mm to the plate, and 5mm to the Matt Chrome.
The pressure to the Matt Chrome should always be stronger than the pressure to the plate.
Otherwise, If you still have the same problem you can change the timing of the oscillation, this can help.
Instructions are in the operators manual, it's easy to do and can't do any damage (unless you leave the bolt loose).
Just take a photo of the setting before you move it in case you have to return to the original setting.
Good luck.
Cheers Phil

Thank you for reply.
Yes this makes a lot of sense.
I am going to go through all these settings
Cheers