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Printing Units Troubleshooting - Slurring

Definition:  Slurring takes place when slippage during the image transfer process.


Problem:  Poor tension control.
Description:  If the printing units have too much control of the nip, it may cause tension variations from unit to unit.  
Solution:  Increase or decrease the tension at your infeed unit until it goes away.  Follow the basic tension principles for web offset printing.


Problem:  Poor blanket tension.
Typical slur patch
Description:  The blanket is loose and not secured to the printing cylinder.
Solution:  Torque the blanket to spec.  To not over tighten as this will cause other problems.  It should only be tight enough to prevent slippage and preserve it's properties.


Problem:  Form oscillation.
Description:  Form rollers that are designed to help with ghosting, will move from side to side.  This is good only to the extent that it will prevent ghosting.  
Solution:  Many times the oscillation can be turned off by securing the ends of the roller.  


Problem:  Worn gears or bearings.
Description.  Bearings or gears that are starting to wear will cause slight hesitations in the printing unit or even gear streaks.
Solution:  Check the following - cylinder bearings, gears and even form roller bearings.  Replace any that are worn or simply heating up during the run.  


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