Mechanical comparison
Check for loose adjustment points, contaminated rollers, damaged peel edges, liner build-up and uneven take-up.
Fault-finding guide
Front and back labelling machine troubleshooting guide
A structured fault-finding route for twin-side and multi-head labellers, from pack handling and sensing to web tracking, wipe-down and speed.
On this page
Troubleshoot the process in the same order every time
Front and back labelling faults often have more than one possible cause. Changing several settings together can hide the real problem and make the next format harder to reproduce. Work from the pack path to the label path, then the application contact and running speed.
- Pack condition: confirm the correct container, fill weight, cap and surface condition.
- Product handling: check orientation, guides, belts, hold-down, spacing and transfer.
- Label roll: confirm material, gap, web width, core, winding direction and damage.
- Sensing: check product trigger and label-gap or clear-label sensor response.
- Dispense path: inspect web tracking, liner tension, peel plate and take-up.
- Wipe-down: confirm pressure, contact point and that fresh edges are not disturbed.
- Timing and speed: compare delay, dispense speed and conveyor speed with the recorded format.
Safe working: follow the machine manual and isolation procedure. Do not reach into moving machinery, defeat guards or bypass safety devices to diagnose a fault. Use a competent engineer where the task exceeds normal operator adjustment.
Symptom table
Where to start when the finished label is wrong
| Both labels drift together | Check product position, conveyor speed, common trigger, container movement and changes in pack spacing. |
|---|---|
| Only one label drifts | Compare that head’s sensor, roll, web path, delay, dispense speed, peel plate and wipe-down. |
| Label is consistently offset | Verify the nominal datum and recipe setting before treating a repeatable offset as random variation. |
| Label skew varies pack to pack | Look for container rotation, rocking, unstable guide contact, varying fill weight or inconsistent wipe-down. |
| Wrinkles or bubbles | Check panel geometry, label size, application angle, wipe-down pressure, surface condition and label construction. |
| Edge lift or flagging | Check panel radius, mould seams, contamination, adhesive suitability, storage condition and later guide contact. |
| Missing label | Check product sensing, label sensing, roll end, liner break, head-ready signal and fault recovery. |
| Double feed or wrong gap | Inspect the label gap, transparent construction, sensor teach, liner variation and web tracking. |
| Front/back mismatch | Confirm both recipes, roll identity, artwork orientation and whether one head recovered differently after a stop. |
| Fault only at higher speed | Review product spacing, acceleration, label dispense, belt contact, liner take-up and downstream restriction. |
Twin-head diagnosis
Use the unaffected head as a comparison
Where two similar heads apply labels to the same pack, the stable head provides useful evidence. Compare roll construction, sensor status, web path, head angle, peel-plate position, wipe-down and recorded settings. Do not assume the heads should have identical values: front and back labels may differ in size, material and required position.
Electrical comparison
Review sensor indication, alarms, product trigger, encoder relationship and the selected recipe without changing multiple parameters.
Material comparison
Swap only when authorised and useful. Different label or liner batches may behave differently even when artwork looks identical.
Specialist guides
Follow the fault into the correct detailed check
Wrinkles and bubbles
Pack shape, wipe-down and label construction.
Adhesion and edge lift
Surface condition, adhesive and storage.
Sensor faults
Opaque, film and transparent label detection.
Web and peel path
Roll alignment, tension, peel plate and wipe-down.
Need a repeatable fault reviewed?
Record the product format, label batch, settings, speed, alarm history and clear photographs or video of the fault. Lancing can use that evidence to distinguish an operator setup issue from a material, sensor, handling or mechanical problem.