Folder Troubleshooting Guide - Quarter Fold

Troubleshooting Crooked Fold At Chopper / Quarter Fold

Problem: Glue lines or backbone wetting not lined up.
Description: For web presses that run magazines with glue or a backbone wetting solution along the spine of the quarter fold, it is important that all glue or water lines line up exactly, one on top of the other.
Solution: Line up all the glue heads to the exact point where the chopper blade hits the copy. To ascertain this point, turn off the glue heads temporarily and see where the chopper hits. Then glue lines can be lined up to this point.

Problem: Chopper table brushes not set properly.
Description:  At the chopper table head stop, a set of brushes will push down on the lead edge of the copy. This assists with the following:

  • Slows down the product
  • Assists in preventing dog ears on the edges as it descends into the quarter fold nips
  • Can correct the product that is coming in crooked.

Solution: Stop and set these brushes evenly against the product. Start up and gradually increase or decrease the pressure of these brushes evenly. This is really a work of art and requires experience and a good feel for how the brushes work.

Problem: Magnetic brakes not set properly.
Description: For presses such as ones that Man Roland makes, magnetic brake skis stop the copy as it enters the chopper fold area. These skis can wear over time and the solenoids can sometime stop working. Additionally, the impact force for each can be adjusted for different stages of the braking process.
Solution: Check each ski for wear and replace as necessary. Run a test on each solenoid to ensure it works. Adjust initial and secondary forces as required.

Problem: Poor timing of chopper blade.
Description: Each chopper fold table has a sweet spot for timing. Usually, this spot occurs in the following way - The chopper blade touches the product at about 1/2 inch before it touches the head stop. This will vary based on the speed of the press.
Solution: Adjust the chopper timing as necessary. The principle is that the product will just "kiss" the head stop before it goes down the quarter fold nips. If it hits the head stop any harder, tears or jams will occur. Any less and folding will not be stable.

Problem: Dirty chopper table
Solution: Clean the quarter fold nips as well as the table itself. Inspect all the belts and the idlers for any buildup. Buildup on the idler rollers can increase or decrease belt speed or even create different nip pressures against the copy.

Problem: Poor tucker blade and jaw not releasing properly.
Description: To diagnose this problem, look for patterns in the delivery and compare that to the timing of the pin and tuck cylinder as well as the move able jaw cylinder. For example: If you have a 2:5:5 system and the problem is occurring every 5 copies, then you know that there is either a jaw or tucker blade not working properly. If it occurs every other copy, then you have a cutting block problem. If it occurs every 10 copies, then you have a tucker blade and jaw cylinder not function well together.
Solution: Look for the patter and adjust the jaws as necessary. Many web pressmen will remove a different pin at each point on the first cylinder to help identify and diagnose the copy that is not delivering properly.

Problem: Linear perf not lined up.
Description: An additional way of getting stability on the chopper table is to run a linear perf just below the first nip after the former board. This is of course only possible where the final product will be perfect bound.
Solution: To increase stability, ensure that if you are running a linear perf, that it is lined up perfectly with where the chopper blade hits.

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