Fit problem SM52-5

[amsl]

Recently we have been having issues with the fit on the magenta (4th unit) on our SM52-5, it is consistantly printing smaller over the whole sheet compared to the other units. We have tried all the usual things like packing and different blankets etc, but nothing seems to make the slightest difference to it, it is like it on all stocks aswell. Then yesterday i discovered that one of the other operators had had one of the automatic blanket wash rolls come off and jam between the blanket cylinder and impression cylinder. i only found this out as i found the remains of the wash roll underneath the machine! Has anybody got any suggestions as to what it could of done to cause the fit problems we are now having, as this is the only thing i can put it down to.
Thanks

 

[mrheidelberg]

Recently we have been having issues with the fit on the magenta (4th unit) on our SM52-5, it is consistantly printing smaller over the whole sheet compared to the other units. We have tried all the usual things like packing and different blankets etc, but nothing seems to make the slightest difference to it, it is like it on all stocks aswell. Then yesterday i discovered that one of the other operators had had one of the automatic blanket wash rolls come off and jam between the blanket cylinder and impression cylinder. i only found this out as i found the remains of the wash roll underneath the machine! Has anybody got any suggestions as to what it could of done to cause the fit problems we are now having, as this is the only thing i can put it down to.
Thanks

Can you get an engineer to clock the cylinders on that particular unit ?

 

[rbailleu]

we had a 2 color with the same problem. one of the cylinders is pushed out of round. most likely the impression as the blanket cyl moves so would just be pushed back. could be checked out with a dial indicator by heidelberg or some one else. easy fix pack either magenta imp cylinder or all the others. cheap proper fixif it works loosen cylinder journals and reseat retighten you will need a mechanic for1- 2 days. expensive fix $10,000+ new impression cylinder and 3 days for 2 mechanics.

 

[max]

i had the same problem on my 2 colour sm52, the impression jacket had been changed after damage and the new jacket was different, slighty thiner

 

[Peter R]

You can also check if the cylinder has been knocked out of round by printing a dry solid. Install a new blanket and packing. Set up on full size sheet, preferably an art paper. Print a solid with the dampers disengaged. Back the impression off until the image appears mottled. Keep backing the pressure off & if the cylinder has taken a knock it will show up as a low area on the sample. You may see whole low areas across the center, front , back or more on the drive or operator sides. Having samples like this to aid an engineer before they arrive on site is a great help & assist them in where to check with their dial gauge.

I also agree with Max that the installation of a miss matched impression jacket can also cause print length issues. The oem jacket has a vulcanized plastic sheet on the back which most aftermarket jackets don't have. The plastic is there to reduce the corrosive effects of the two metals. If you have miss matching jackets the slightest difference in thickness will cause print length issues.

 

[amsl]

Thanks for the replys. We have had the cylinder clocked and it was slightly out but the problem is still there, its not horrific but its not perfect. We have had some new impression cylindar jackets fitted on some units including this one. They were all purchased from Heidelberg, do all the units have the same jackets?, They all had the vulcanized plastic on the back. Since we had the cylinders clocked it seems to be side to side rather than over the whole sheet.
Thanks for your help.