Labeling machines are core equipment on packaging lines and are widely used in food, pharmaceutical, household and personal care, and electronics industries. After long operation or incorrect use, faults such as crooked labels, bubbles, missed labels, and label breaks can appear. This article lists 10 common faults and their fixes, applicable to round-bottle, flat-surface, side, and inline labeling machines, and useful for shop-floor troubleshooting, after-sales training, customer guidance, and routine maintenance.
Quick reference table of common faults
| No. | Symptom | Main cause |
|---|---|---|
| 1 | Crooked labels | Positioning offset / uneven pressure from the pressure roller |
| 2 | Bubbles and wrinkles | Speed too high / dirty surface / unstable tension |
| 3 | Intermittent missed labels | Photoelectric sensor fault / product speed too high |
| 4 | Double or multiple labels applied | Photoelectric sensor false trigger / substandard label stock |
| 5 | Frequent label breaks | Excessive tension, burrs on the cutting edge, poor-quality labels |
| 6 | Inaccurate label position | Parameter delay deviation, unstable conveyor speed |
1. Crooked, offset, or uneven labels
Cause 1:The gap in the product guide rails is too large, so products sway from side to side and drift off center.
Solution:Fine-tune the conveyor guide rails to match the product size, keeping products centered and stable with no swaying.
Cause 2:Uneven pressure from the label application roller, so the rolling force is inconsistent.
Solution:Adjust the pressure roller evenly so the entire label is rolled with consistent force.
Cause 3:The peel plate is tilted, so the label dispensing position is offset and not parallel to the labeling position on the product.
Solution:Correct the horizontal and vertical angles of the peel plate and clear any debris from the edge to ensure straight label dispensing.
Cause 4:Product positioning guides are not calibrated, so incoming products arrive in inconsistent orientations.
Solution:Recalibrate the guide positioning plates to make product infeed position and orientation consistent.
Cause 5:The label reel is loose, brake damping is unstable, or the reel is not aligned on the same horizontal line, so the label drifts as it runs.
Solution:Lock the label reel, adjust the damping force, and keep the label web running steadily without drift.
Cause 6:The labels are not made to standard, adhesion drops after long storage, and inconsistent gaps between labels cause vertical and longitudinal offset.
Solution:Use a professional tool (calipers) to measure the label gap and keep it consistent.
2. Bubbles, wrinkles, and uneven labels
Cause 1:Labeling speed is too high and the pressure roller cannot keep pace with label dispensing.
Solution:Reduce the running speed and label at a steady rate to match the rolling pace.
Cause 2:Oil, water stains, or dust remain on the product surface, affecting adhesion.
Solution:Clean the product surface before production to ensure it is free of oil, water, and dust.
Cause 3:Label unwind and rewind tension fluctuates, making the web unstable.
Solution:Adjust rewind and unwind damping to keep label tension constant and avoid tightening and loosening.
Cause 4:The pressure roller is aged, worn, or lacks elasticity, so it does not press the label down properly.
Solution:Replace worn or hardened pressure rollers to ensure flat rolling.
Cause 5:Bottles slip or rotate unevenly during round-bottle labeling.
Solution:Adjust the height and pressure of the bottle support rollers and holding rollers so bottles rotate at a steady speed without slipping.
3. Missed labels, intermittent labeling, labeling that starts and stops
Cause 1:The product detection sensor sensitivity is too high or too low, so the detection signal is unstable.
Solution:Re-adjust the sensor sensitivity and calibrate the detection distance.
Cause 2:The production line runs too fast or products are spaced too closely, so the sensor cannot pick up a signal.
Solution:Reduce the conveyor speed and increase product spacing to ensure stable detection.
Cause 3:Dust buildup or obstruction on the sensor lens causes detection to fail.
Solution:Clean the sensor lens regularly (do not use thinner) and keep it clean and unobstructed.
Cause 4:The label dispensing delay parameter does not match, so labels are peeled too early or too late.
Solution:Fine-tune the advance and delay parameters to match when the product arrives.
Cause 5:The conveyor belt slips, so product spacing becomes irregular.
Solution:Tension the conveyor belt, check it for wear, and replace it promptly if aged.
4. Double labels, consecutive labels, two labels on one product
Cause 1:Light, reflections, or debris interfere with the sensor, causing false dispensing triggers.
Solution:Adjust sensor sensitivity and detection angle to avoid reflections and interference.
Cause 2:The label liner is translucent or label spacing is non-standard, so the machine misreads the signal.
Solution:Use qualified labels with standard dimensions and an opaque liner (glassine liner recommended).
Cause 3:Stepper labeling parameters are disrupted, so the label feed length is abnormal.
Solution:Reset the stepper labeling parameters and restore the machine calibration data.
Cause 4:Product pileups or jams on the line cause repeated detection.
Solution:Organize material flow on the line so products convey in order without pileups or jams.
5. Label breaks and frequent label tearing
Cause 1:Unwind brake damping is too tight, so excessive overall tension tears the web.
Solution:Loosen the reel damping and reduce overall label tension so the web runs with proper slack.
Cause 2:Burrs or a sharp edge on the peel plate cut through the label liner.
Solution:Polish the peel plate edge to remove burrs and keep it smooth and flat.
Cause 3:The label material is poor quality, the liner is brittle, or the adhesive has aged.
Solution:Switch to certified pressure-sensitive labels and avoid substandard consumables.
Cause 4:The waste-label rewind pull is too strong and tears the label web.
Solution:Reduce the pull of the waste-label rewind motor to avoid overstretching the labels.
6. No label dispensing, machine does not feed labels
Cause 1:Machine parameters are corrupted or the program has stalled, so the motor does not run.
Solution:Restart the machine, reset the labeling parameters, and restore the initial state.
Cause 2:The product sensor gives no detection signal, so the machine receives no dispensing trigger.
Solution:Check the sensor indicator light and readjust the detection position and sensitivity. If adjustment does not solve the problem, the label may be outside the sensor’s working range or the sensor may be damaged; consult the manufacturer.
Cause 3:The label is jammed in the peel plate or the web path and stuck.
Solution:Stop the machine, clear the jam, and re-thread the label web correctly.
Cause 4:The emergency stop is pressed and the machine is in protective lockout.
Solution:Reset the emergency stop and check for protective faults before clearing the lockout.
7. Inconsistent label position, labels placed too far forward or back, poor positioning
Cause 1:The dispensing delay parameter does not match the conveyor speed.
Solution:Fine-tune the dispensing delay parameter to suit the running speed of the machine.
Cause 2:Conveyor belt speed is unstable, speeding up and slowing down.
Solution:Calibrate the conveyor motor speed to keep it constant throughout.
Cause 3:Product sizes and orientations are inconsistent, so infeed is irregular.
Solution:Standardize product orientation and use products of consistent specifications.
Cause 4:Stepper motor missed steps or a loose belt cause labeling accuracy deviation.
Solution:Check the motor belt and gear drive, tighten the fittings, and resolve the missed-step issue.
8. Slipping, jerky rotation, and misaligned labels on round bottles
Cause 1:Bottle support roller height is set incorrectly, so the bottle is not held firmly.
Solution:Fine-tune the support roller height so the bottle contacts the rollers fully and evenly.
Cause 2:Dust on the roller surface reduces friction and causes slipping.
Solution:Clean dust and oil from the roller surfaces to restore friction.
Cause 3:Bottle holding roller pressure is too light or too heavy, so bottles rotate abnormally.
Solution:Adjust the holding roller pressure until bottles rotate at a steady speed without slipping or deforming.
9. Abnormal noise, vibration, and jerky label feed
Cause 1:Drive gears and bearings lack lubrication or are worn, increasing running resistance.
Solution:Lubricate bearings, gears, and drive chains with the specified oil at regular intervals.
Cause 2:The label reel axis is not parallel, so the web is pulled off to one side.
Solution:Correct the reel parallelism and coaxiality to keep the web running smoothly.
Cause 3:Debris remains in the label path or drive components.
Solution:Clear debris and dust from inside the machine regularly to keep the path clear.
10. Weak adhesion, lifted edges, and labels that fall off
Cause 1:The product surface is not clean and has dust, oil, or water stains.
Solution:Thoroughly clean the bonding surface before production and keep it dry.
Cause 2:Low workshop temperature or high humidity reduces adhesive activity.
Solution:Keep the workshop ventilated and dry; in cold conditions, pre-warm the label stock.
Cause 3:The pressure roller force is insufficient, so the label is not fully bonded.
Solution:Increase the pressure roller force appropriately so all four edges of the label are firmly pressed.
Cause 4:The label adhesive has expired or the material is poor quality, so tack is insufficient.
Solution:Replace with new, certified, in-date pressure-sensitive labels.
Cause 5:In winter, low temperatures harden the labels and they fall off as they pass through.
Solution:Add a radiant heater to warm the labels.
Routine maintenance guidelines (general)
- Daily maintenance:Clean dust and debris from the detection sensor, peel plate, and conveyor belt; check waste-label removal on the rollers, the label web condition, and roller contact.
- Weekly maintenance:Check the tightness of reels, belts, and gears; tighten loose screws; lubricate drive bearings.
- Environmental requirements:Keep the machine dry and well ventilated; never wash the electrical cabinet with water, and avoid humidity and dust buildup.
- Rust prevention:Spray rust-preventive oil on the stainless steel and iron parts and wipe it evenly with a soft cloth; WD-40 is recommended.
- Shutdown maintenance:For long shutdowns, release label tension and remove consumables to prevent labels from aging and deforming and the machine from staying under load.
If you encounter any of these issues with your labeling machine and cannot resolve them yourself, contact the Wanzhi Automation technical team for professional support.