Direct answer
Inspect the defect that matters rather than only “cap present”. Define acceptable height, seating, orientation, tamper-band and component conditions, stabilise the container, select sensing or vision for the feature, and verify tracking and rejection at normal line speed.
Separate presence from correct closure
A simple sensor can detect an object above the neck but may not distinguish a high cap, crossed thread, missing liner, incomplete tamper band or wrong colour. List each defect and its risk before choosing the method.
Measure acceptable cap height and tilt using drawings and good production samples.
Control container presentation
Bottle lean, variable base height, neck movement and guide contact can make a good cap appear faulty. Use stable conveyor transfers and guides that do not obscure the inspection feature.
For trigger or pump closures, the orientation of the head and dip tube may need separate checks.
Choose sensor or vision technology
Photoelectric, laser displacement, ultrasonic, inductive or camera systems suit different features and materials. Transparent caps, reflective metal and coloured closures need practical trials.
Use multiple measurements where one signal cannot distinguish all unacceptable conditions.
Link inspection to process control
Reject the affected container and count defects by capping head, cap batch or time. A rising high-cap trend can indicate feed, chuck, spindle or bottle-support deterioration.
Define the response to repeated faults and failed rejection so defective closures do not continue to packing.
Information to prepare
- Closure and neck drawings
- Good and defective sample set
- Height, tilt and component tolerances
- Container-stabilisation method
- Sensor or camera performance at line speed
- Reject tracking and confirmation
- Defect trend by head, batch or time
Capping Machines UK
Capping-machine selection and closure-application routes for multiple cap types.