Doubling and misregister on our CD 74

[Raman karthi]

Dear sir,
I have problem in our CD 74 machine , double image and misregister on all thickness of paper and board. We have checked cam follower is looking good.

How to rectify it.please any information are helpful.
Thanks.

 

[Mathew]

In which direction you have misregistering? Lateral or circumferential?

 

[Raman karthi]

Circumferential direction sir and both edges are better and middle of sheet is more problem and one sheet and third sheet register same and second and fourth sheets are same register

 

[Adil]

You have to check the calibrated sheets covering the blanket cylinder, it must be a blue calibrated sheet 0.4 in thickness

 

[Raman karthi]

That packing sheet is o.4 mm we are using sir

 

[Adil]

The causes of doubling are Differences in stretchability, roughness, thickness, absorption capacity of the support, tensions due to an unfavorable distribution of the pattern or to large climatic Differences between the paper and the atmosphere of the workshop. printing, high ink tack or damaged machine seized gripper.
So to solve these problems I suggest solutions in order of cause as follows:
Improve the press settings (feeder, clamps, turning system), change the support, adapt the climatic conditions of humidity in the stack and ambient in the workshop, reduce the ink tack, reduce the settings between blanket and counter cylinder pressure.
Good luck

 

[Raman karthi]

The causes of doubling are Differences in stretchability, roughness, thickness, absorption capacity of the support, tensions due to an unfavorable distribution of the pattern or to large climatic Differences between the paper and the atmosphere of the workshop. printing, high ink tack or damaged machine seized gripper.
So to solve these problems I suggest solutions in order of cause as follows:
Improve the press settings (feeder, clamps, turning system), change the support, adapt the climatic conditions of humidity in the stack and ambient in the workshop, reduce the ink tack, reduce the settings between blanket and counter cylinder pressure.
Good luck

Thanks for the information sir.

 

[Mechanica Speedmaster]

I would suggest to put a straight lineal on the transport gripper pads in order to check if the gripper pads are in same line. Check both gripper bars on the transport cylinder!

 

[Raman karthi]

I would suggest to put a straight lineal on the transport gripper pads in order to check if the gripper pads are in same line. Check both gripper bars on the transport cylinder!

Dear sir we have checked all unit impression cylinder and transfer cylinder cam follower, but some unit transfer cylinder cam follower is little playing , and we have checked impression cylinder gripper bar pad pressure is putting same tension.

You mean transport cylinder is impression or transfer cylinder?

 

[Mechanica Speedmaster]

I mean transfer cylinder, sorry to confused you. I dont mean in first plan to check the gripper tension ( this would be next step) but to check as i wrote if the gripper pads are all in line- they have to be straight. If you have any play in cam followers than you have to replace them, do yourself a favour ..., you have to eliminate all possibilities.

 

[turbotom1052]

Have you checked all grippers for freedom of movement? If you GENTLY pry open the grippers off their pads you will feel any that may be sticking. If you encounter sticking grippers you may want to consider cleaning the grippers and gripper shafts with kerosene applied with a paint brush, working the kerosene into all areas of grippers, pads, shafts, and bushings. Be sure to dry off thoroughly the kerosene, finishing it all off with a good greasing. If you find any of the zerk fittings not wanting to take grease, it must be addressed.

 

[Raman karthi]

Have you checked all grippers for freedom of movement? If you GENTLY pry open the grippers off their pads you will feel any that may be sticking. If you encounter sticking grippers you may want to consider cleaning the grippers and gripper shafts with kerosene applied with a paint brush, working the kerosene into all areas of grippers, pads, shafts, and bushings. Be sure to dry off thoroughly the kerosene, finishing it all off with a good greasing. If you find any of the zerk fittings not wanting to take grease, it must be addressed.

Ok sir thanks for the advice, we have cleaned All impression grippers and grease filled.

 

[Raman karthi]

I mean transfer cylinder, sorry to confused you. I dont mean in first plan to check the gripper tension ( this would be next step) but to check as i wrote if the gripper pads are all in line- they have to be straight. If you have any play in cam followers than you have to replace them, do yourself a favour ..., you have to eliminate all possibilities.

Ok sir , will check pad line and change cam follower.

 

[turbotom1052]

Ok sir thanks for the advice, we have cleaned All impression grippers and grease filled.

All grippers should be cleaned and greased. Not just the impression cylinder gripers!!!

 

[Raman karthi]

All grippers should be cleaned and greased. Not just the impression cylinder gripers!!!

Ok sir thanks for information