Paper Bag Machine Troubleshooting FAQ

Why is the bag bottom not pasting properly?

Poor bottom pasting traces to glue temperature or viscosity off spec, glue roller gap and doctor blade wear, or paste timing against the folding station. Check the glue's working temperature first, then the roller film thickness, then the timing of paste application versus the folding sequence.

What causes creases on a paper bag machine?

Creases usually come from uneven tension across the web, worn folding boards, or misaligned scoring. Check tension balance left to right first, then the folder geometry and scoring depth — creases that appear at one side only point to tension, creases everywhere point to the folding section.

Why do rejects climb when the bag machine runs faster?

Speed-linked rejects mean a station cannot keep up with the web: glue application lagging at higher speed, knife timing drifting, or vacuum transfer missing. Slow down and confirm each station's timing at speed, then correct the limiting station — pushing speed beyond what the glue and transfer can follow only converts rejects into more rejects.

How often should the glue system be checked on a bag machine?

Check glue temperature and viscosity at shift start and after every glue top-up, and inspect the roller gap and doctor blade weekly or with every major job change. Glue is the most drift-prone consumable on a bag line, so the check that catches it early is the one that prevents the most bottom-pasting rejects.

Why does the bag knife tear instead of cutting clean?

Tearing usually means a blunt blade, worn or damaged anvil, or cut timing that is out of sync with the web. Inspect the blade edge and anvil condition first — if both look sound, verify the timing mark alignment, because cutting on the wrong part of the cycle makes even a sharp blade tear.

What should I check first when tension keeps drifting?

Work back from the unwind: brake condition and setting, dancer roll response, reel splice quality, and web path alignment. Tension faults that come and go usually point to the brake or a bad splice; tension faults that grow through a reel point to the unwind or the dancer. Log which one appears and the cause narrows itself.