When a 3PL's autobagger starts misfeeding three times an hour, the first phone call is always to the bagger manufacturer. The second is to the maintenance tech. The third — sometimes weeks later, when the bag supplier is finally brought into the conversation — is when somebody actually measures the bag.
Here's what gets missed: the bag almost always passes a manual inspection. The bag opens. The flap seals. The dimensions print as labeled on the case. What it doesn't have is the width tolerance the bagger needs.
What “tolerance” means in this context
A bagger doesn't run on the labeled width of the bag. It runs on the consistent width — the standard deviation, bag to bag, across the same roll. A 9.000″ bag that runs at 9.000″ ±0.030″ all day will autofeed cleanly. The same 9.000″ bag running at 9.000″ ±0.080″ will jam every twenty minutes — even though every single bag passes the spec sheet.
Most off-the-shelf poly mailers don't publish their width tolerance, because at the gauge most catalog distributors stock — extruded on a fixed die, no inline gauge monitoring — the actual tolerance is in the ±0.060″–±0.090″ range. It's fine for a hand-pack station. It's not fine for a 90 bag/min Autobag, ePac, or Sharp tabletop bagger running 12-hour shifts.
What's actually causing the jam, in order of frequency
- Width drift across the roll. Bag #1 measures 9.000″. Bag #50,000 on the same roll measures 9.070″. The bagger's hopper centers on 9.000″ — at bag #45,000 it's misfeeding.
- Inconsistent film stiffness. Resin blend changes batch to batch. Stiffer film feeds; limper film slumps and double-feeds. This is the silent jam.
- Static. Bags cling to each other coming off the case. The anti-static spec lives in the resin formula, not in a topical spray.
- Edge curl. Cooling-tower temperature drift during extrusion produces an inside-curl the bagger's vacuum heads don't pick up cleanly.
What to ask your supplier
A vertically integrated supplier — meaning they extrude their own film and convert it on their own lines — can answer three questions a converter-only supplier can't:
- What was the gauge variation on the last lot you shipped me? They should have the inline gauge-monitor data per roll.
- What was the resin blend lot, and is it the same blend as the previous shipment? Resin substitution is the silent autobagger killer.
- Can you run a test lot at the spec you'd recommend and let us pull it on our line before we commit the production order? Custom extrusion can adjust the layer balance for stiffness without changing the dimension on paper.
If the answer is in catalog terms — “we stock 9×12, 10×13, 14×19, that's what we have” — they're not in the bagger conversation. They're in the warehouse conversation. You're going to keep paying the bagger tech $180/hr to diagnose film.