GTO 46 Register Issue

[aqazi81]

GTO 46 2 Color press showing strange register problem,
2nd unit register moving back and forth only from OS around 1-2 mm. This is happening only on Art coated paper, Strange thing is when we run the press with one unit impression off then there is perfect register. Also the press operator told me that the impression indicator on OS on 2nd unit also moves gradually during production run towards + sign.

Any Ideas?

 

[mantman]

Did you check plate being tight, perhaps it`s plate clamping bar?
Though if impression rises to + that means there is more pressure at paper therefore change of registration. When you switch off unit II, impression continues to + sign?
Also check feeding grippers bite why only coated paper cause problems

 

[contractor]

Try checking all the cam followers on all cylinders make sure they are not seized or with flat spots. If you can try to get the cylinders in a position where you can push down on the grippers to release the spring pressure and feel the follower to see if there is too much up and down movement. It should feel like a bearing. Also on the plate cylinder there is a drive pin that is bolted with 4 - 5mm Allen key bolts this can sometimes wear and give movement problems. It's on the drive gear and you can see it if you open the little door. Also try cleaning your pads and grippers.

 

[aqazi81]

Thank you all for your input, I'll check all these things and update you.

 

[eriktheprinter]

Short grain stock? If it is only on that particular stock....Or stock affected by temperature / humidity? If you eliminate the stock, next is transfer between units like contractor said- cam follower or sticky gripper most likely culprit. Lightweight stock? Heavy coverage?

 

[aqazi81]

Just to update you, It was gripper setting issue on 2nd Unit impression cylinder.

Thank you all for your help.