Problem. In FIBC fabric production, the most common symptom is a batch of panels that should be identical but are not. Operators see panels from the same batch coming out at different lengths, side-seam or bottom-panel alignment that refuses to line up, constant manual re-measuring at the cutting station, and a panel length that changes again the moment the fabric roll is replaced. None of these points to a single fault, which is exactly why the defect keeps returning even after a machine setting is adjusted.

Possible Causes

• Cut length setting does not match the panel development drawing. If the number entered into the machine does not match the flat panel layout, every piece is consistently wrong.
• Roll tension or material stretch. Woven PP fabric fed under variable tension stretches unevenly, so the same setting produces a different real length from roll to roll.
• Fabric roll lateral drift. A roll that walks sideways feeds at an angle and cuts the panel off-square.
• Hot-cutting temperature changing the cut edge. Temperature affects how the cut edge behaves, and an unstable setting adds variation to the finished panel.
• No first-piece check after a size change. Switching bag size without a fresh trial cut lets the previous order's error carry straight into the new one.

Inspection Sequence

Work through the checks in a fixed order, so that one confirmed cause is not masked by another:

1. Measure the first piece before running the batch.
2. Check roll tension and the web-guiding position.
3. Verify the cut length setting and the seam allowance.
4. Re-sample the panel after every roll change or length change.

Reference Parameters

What the Numbers Do — and Do Not — Mean

The ±2 mm figure is the machine's rated cutting accuracy. It is not a zero-error guarantee under every material, every speed and every working condition. Tension, material stretch and roll condition still influence the real panel length, which is why the inspection sequence above matters as much as the specification sheet. Treat the parameter as the basis for a controlled process, not as a promise that can replace first-piece measurement. For a plant producing uneven FIBC panel size or inconsistent FIBC fabric length control, the fastest route to a stable result is to fix the length setting first, stabilise roll tension and guiding second, and re-verify the first piece after every change.