Web Press Troubleshooting Guide - Folder - Tears Quarter Fold Table

Description:  After the printed signature leaves the jaw cylinder, completing its first fold, the then enters the quarter-fold area.  If the quarter fold is engaged, there are functions of the process that can cause tears.

Problem:  Tears happening at the lead edge of the signature.
Description:  The lead edge refers to the part of the signature that is already folded once.  This copy just "kisses" the head-stop before being pushed down through the quarter-folding nips by the chopper blade.  This timing is critical for success.
Solution:  This is most commonly a timing issue.  Adjust the timing of the chopper blade to allow the signature to barely touch the head-stop before going down.  If the chopper blade goes down too soon, it will cause an uneven fold as there is less control of the signature.  If the chopper blade goes down too soon, it will cause tearing issues.  

Problem:  Tears happening at tail edge of signature.
Description:  This is also related to timing, but can be a combination of variables.  As the signature it pushed into the quarter fold nips, the copy can be difficult to control.  All kinds of flipping and twisting can occur, which may cause random rips.
Solution:  Adjust timing and quarter-fold nip tension on the copy to get the right combination.

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