Labelling fault guide

How should labelling machine faults be diagnosed?

A structured method for tracing label faults through product presentation, web handling, detection, dispense, wipe-down and adhesion.

Safety first

Preserve the labelled pack and roll evidence before adjusting the applicator.

Make the equipment safe under the site's procedures, retain the affected pack and record the label roll, product format, sensor state and last production event. Do not reach into moving conveyors, wrap stations or liner take-up mechanisms.

Labelling faults should be divided into product presentation, label-web handling, detection, dispense, application and adhesion. An applicator setting cannot correct a pack that arrives at a different datum on every cycle.

Capture before reset

Product and label format
Label roll, batch and roll direction
Fault position on the pack
Guide, sensor and peel-plate condition
Web path and liner take-up
Recent roll, product or changeover event
Acceptable and failed packs

Symptom guide

Separate product, web, sensor and adhesion causes

Observe the first point at which the process departs from normal.

Symptom	Evidence to inspect	Diagnostic boundary
Label position varies	Product datum, guides, spacing, sensor timing, belt slip and container variation	Confirm product position before label dispense
Label skew	Product angle, web tracking, peel-plate alignment, speed match and wipe-down direction	Determine whether skew starts at leading-edge application
Bubbles or wrinkles	Surface condition, label material, adhesive, application pressure, curvature and speed	Map the defect to the pack feature and application sequence
Missing label	Label detection, gap, web break, dispense permission, product sensor and reject logic	Separate failure to dispense from failure to adhere
Two labels feed	Gap detection, transparent material, calibration, web tension and die-cut consistency	Inspect the real production roll, not a substitute sample
Liner break	Web path, edge damage, tension, take-up, roll condition and sharp contact points	Locate where damage begins before the final break

Diagnostic sequence

Start with the product datum and follow the label path

Use one controlled change at a time and keep the original samples.

Confirm the required result.Define label position, orientation, adhesion and any readable-code requirement.
Stabilise the product.Check guides, spacing, orientation and the datum at the application point.
Inspect the label roll.Verify roll direction, gap, die cut, liner, web path and physical damage.
Check detection and dispense.Observe product sensor, label sensor and leading-edge release.
Check application and wipe-down.Compare product speed, label speed, pressure and surface following.
Verify adhesion over time.Inspect the pack immediately and after the period relevant to the production check.

Material and environment

Label performance can change without a machine fault.

Label face stock, adhesive, liner, varnish, ink coverage, roll winding and storage conditions affect dispensing and adhesion. Pack temperature, moisture, dust, oil, product residue and surface energy can change the result. Record changes to both the pack and label supply.

Transparent or metallic labels may require a detection method different from a conventional gap sensor. Flexible or shaped containers may need controlled support so application pressure does not distort the surface.

For technology selection, use the labelling machine types guide. For variable-data faults, also review the data and verification boundary in the print-and-apply guide.

Escalate with

Affected and acceptable labelled packs
Complete label roll or retained roll section
Label specification and batch identification
Photographs showing the agreed datum
Machine format and authorised settings
Video of product entry and application where safe
Recent material, cleaning or environmental changes

Buyer questions

Questions about labelling machine faults

Use the product and label path to locate the first inconsistent condition.

Why do self-adhesive labels bubble or wrinkle?

Labels can bubble or wrinkle when the pack surface is contaminated, curved or unstable; the label material or adhesive is unsuitable; web tension or peel geometry is wrong; product and label speeds differ; or wipe-down does not follow the surface. The defect should be linked to its exact position on the label and pack.

Keep the affected pack and roll identification. Changing pressure may hide the symptom while leaving the material or presentation cause unresolved.

Why are labels applied at an angle or in different positions?

Skew or placement variation can result from inconsistent product datum, guide movement, variable spacing, label-web tracking, sensor detection, dispense timing, product slip or pack-shape variation. First confirm that the product reaches the application point in the same position.

Measure from an agreed physical datum rather than judging by artwork alone. Decoration and container features may themselves vary.

Why does a label sensor miss or double-feed labels?

A label sensor may miss or double-feed when the gap, liner, label material, print, transparency, calibration, web tension or sensor position is unsuitable or inconsistent. The sensor technology must match the actual label construction.

Use the production label roll and inspect the gap and die cut. A hand-cut sample or different liner may calibrate successfully but fail on the real roll.