Recognise the symptom before changing settings
Describe what changes, where it first appears and whether it follows a product batch, packaging batch, filling head, lane, speed, temperature or time in the run. Typical observations include:
- caps lean after application
- torque spikes or capping heads stall
- leaks appear despite high torque
- thread or tamper-band damage is visible
Likely causes to separate
A symptom can have several unrelated causes. Treat the following as hypotheses to test rather than a list of settings to change at once.
- cap released off-centre or at the wrong height
- bottle neck not controlled under the chute or pick head
- incompatible or damaged threads
- capping force applied before initial engagement
- container spinning or tipping
Check in this order
Check 1
Observe cap placement at low speed before torque.
Check 2
Check caps and neck finishes from multiple batches.
Check 3
Measure chute, pick-and-place or cap-drop alignment.
Check 4
Verify top pressure and bottle side support.
Check 5
Inspect whether the cap completes an initial turn freely.
Corrective actions to evaluate
After the cause is demonstrated, select the least disruptive correction that returns the process to a safe, repeatable and approved state.
- centre and stabilise cap placement
- adjust application height and top load
- improve bottle control and star/guide setup
- remove damaged or incompatible packaging
- use a capping method suited to the closure geometry
Prevent the problem returning
- approve cap-neck combinations through line trials
- inspect cap handling change parts
- keep cap dust and flash out of the feed system
- include cross-thread reject detection where risk justifies it
Record evidence, not only the final setting
Capture the product and packaging batches, machine recipe, head or lane, speed, temperature, vessel level, symptom frequency, intervention and post-correction results. This creates a usable centreline and allows recurring loss to be prioritised through OEE or downtime analysis.
Common questions
What is the first check for caps cross-threading or sitting crooked?
Observe cap placement at low speed before torque.
What commonly causes caps cross-threading or sitting crooked?
Common causes include cap released off-centre or at the wrong height, bottle neck not controlled under the chute or pick head, incompatible or damaged threads.
Should the machine be adjusted immediately?
Change one controlled variable at a time after the measurement method, product condition, packaging and safety state are confirmed.
When should production be stopped?
Stop and follow the site safe-isolation and escalation procedure when there is risk of injury, contamination, fire or explosion, uncontrolled product release, damaged guards, unsafe pressure or an unverified quality result.
What information should be recorded?
Record product and pack batch, recipe, machine settings, filling head or lane, time, temperature, speed, symptom, corrective action and the evidence that performance returned to the approved condition.