Fault-finding guide

Packaging line troubleshooting

Use a structured fault record to separate the visible symptom from its cause, confirm the operating context and verify the correction without bypassing safety measures.

Safe first response

Stabilise the process, preserve evidence and avoid random adjustment.

Stop or isolate the equipment when required by the machine instructions, site procedure or risk. Do not reach into moving equipment, defeat an interlock or bypass a guard to observe a fault. Maintenance and fault-finding must be carried out by people competent for the task.

Record the exact symptom before changing settings. Note the product, format, recipe, batch, machine state, alarm, recent changeover, speed condition and where the last accepted pack was produced. Photograph or retain a defective sample where site rules permit.

Change one verified cause at a time. Multiple simultaneous adjustments can hide the real fault and make the next failure harder to diagnose.

Minimum fault record

Date, time, machine and product format
Observed symptom and alarm text
Running, starved, blocked or restart condition
Recent cleaning, maintenance or changeover
Defective sample or image where appropriate
Action taken and part or setting changed
Verification after restart

Symptom matrix

Start with the stage where the defect first appears.

Symptom	Check first	Possible process causes to verify
Intermittent fill variation	Product supply, temperature or condition, air in feed, container position and nozzle state	Unstable head pressure, inconsistent product, incorrect recipe, worn or contaminated dosing parts, movement during fill
Drip, string or splash	Nozzle position, shut-off condition, product behaviour and container opening	Product viscosity change, unsuitable nozzle action, fill profile, delay or unstable container
Cap cross-thread or incomplete closure	Cap orientation, placement, neck finish, bottle support and tightening alignment	Mixed or damaged components, poor presentation, off-centre placement, container rotation or incorrect tooling
Label skew, wrinkle or bubble	Container datum, label web tracking, peel point, wipe pressure and surface condition	Variable container geometry, unstable handling, label construction, tension, sensor setup or application speed relationship
Code missing or unreadable	Data state, trigger, substrate, print distance, consumable condition and inspection result	Incorrect product detection, poor surface, wrong recipe, print-head condition or unconfirmed reject
Frequent conveyor stops	Where accumulation begins, pack stability, guide pressure and downstream availability	Line imbalance, unsuitable transfer, false sensor detection, uncontrolled back pressure or restart logic

Cross-machine faults

The first machine to stop is not always the source of the problem.

Starved

Look upstream for product supply, component replenishment, spacing or control signals that prevent the next cycle from being released.

Blocked

Look downstream for capacity, reject confirmation, case packing, accumulation or an unstable transfer that consumes the available space.

Restart repeat

Check whether in-process packs, counters, recipes and machine states are reconciled before a coordinated restart.

Turn repeated faults into an engineering improvement list.

Trend faults by product and format rather than combining every stop under one description. A problem that occurs only with the tallest bottle, clearest label or least stable case needs a different response from a general machine fault.

Review recurring issues against the controls and sensor definition, changeover method and maintenance plan. Correct the underlying presentation, access or process condition before increasing speed.

For safety information, follow the machine instructions and site procedures. The HSE's machinery safety introduction explains the importance of suitable equipment, maintenance, guarding, isolation and emergency controls.

Escalation evidence

Fault history by product and format
Alarm and control-state record
Images or retained samples
Settings before and after the fault
Parts inspected or replaced
Temporary and permanent action
Result under sustained production

Separate containment, correction and root-cause action.

Containment makes the current situation safe and prevents suspect product from progressing. Correction restores the verified setup or replaces a failed item. Root-cause action removes the condition that allowed the fault to recur. Record all three separately so a temporary reset is not mistaken for a permanent fix.

When a fault follows changeover, compare the current machine condition with the approved format record before adjusting beyond it. Check fitted parts, recipe, guides, sensors, label path, product supply and component identity. When a fault follows maintenance, confirm that guards, connectors, settings, fasteners and test results were returned to the approved state.

Escalate with a reproducible description

Technical support can respond more effectively when the fault can be recreated or bounded. State whether it occurs on every pack, at a particular interval, only after a stop, only with one format or only after a consumable change. Include the last action that reliably clears it and how long the correction remains effective.

After the permanent action, verify the difficult condition and monitor the next representative production run. Close the record only when the symptom and the underlying risk have both been addressed.

Root-cause review

Immediate containment and product status
Verified machine condition
Trigger and repeat pattern
Physical, control, material or method cause
Corrective and preventive action
Documentation or training update
Sustained-production verification

Next step

Send a clear fault record when requesting technical support or replacement equipment.

Send the product, container, closure, label or outer-pack samples that represent normal and difficult production. Include the required task, current process, intended output, available space and any existing equipment that must remain.

Useful enquiry routes

Fault questions

Common questions when a packaging line will not run consistently

Preserve the sequence of events before changing settings or replacing parts.

What should be checked first when a packaging line stops?

First make the equipment and product safe, then capture the original alarm, machine states, pack positions and the last successful cycle before resetting anything. Confirm whether the initiating condition is local to one machine or is a blocked, starved or permission state passed from another stage.

A reset may clear the symptom and erase useful evidence. Photograph or export the event information where the site's procedures allow.

How can a packaging line bottleneck be identified?

Identify the bottleneck by observing which stage repeatedly builds an upstream queue, starves downstream equipment or determines the interval between finished packs during stable production. Include replenishment, minor stops, cleaning checks and operator tasks; the nominally slowest machine is not always the sustained constraint.

Use the output and capacity guide to distinguish cycle capability from production performance.

When should a packaging line fault be escalated to the supplier?

Escalate when the fault cannot be resolved within authorised procedures, involves safety functions, recurs after an approved correction, requires protected settings or software access, or risks damage and product quality. Stop rather than bypassing an interlock or continuing with an uncontrolled condition.

Provide the alarm history, time sequence, video where safe, machine and format details, recent changes and the steps already taken. A reproducible description enables more focused support.

Diagnose filling faults Diagnose capping faults Diagnose labelling faults

Boundary faults

Diagnose component feeding and inspection as complete functional paths.

Repeated stops often appear at one sensor or station even though the initiating cause lies earlier in the material or data flow.

For caps, containers and labels, trace the path from bulk supply through separation, orientation, accumulation and transfer. The feeding guide identifies the states and component behaviours to observe.

For quality faults, follow detection through decision, tracking, physical reject and confirmation. The inspection and reject guide helps distinguish a sensing problem from a tracking, actuator or full-bin problem.

Evidence before adjustment

Exact fault time and line state
Last accepted and first failed pack
Upstream queue and downstream demand
Recipe, format parts and material revision
Sensor input and control decision
Physical result and recovery action

Why does a packaging line fault return after restart?

A packaging line fault returns after restart when the reset clears the alarm but not the material, setting, timing or interface condition that caused it. Record what changes during the reset and inspect the first packs through the affected boundary.

Repeated resets without cause removal can move uncertain product further along the line.

How can a sensor fault be separated from a process fault?

Separate a sensor fault from a process fault by checking the physical pack condition, the sensor input, the control interpretation and the commanded response in sequence. A correct sensor can report a real presentation problem, while a stable pack can expose alignment, contamination, wiring or timing issues in the sensor path.

Feeding systems guide Inspection and reject guide Discuss a line fault