Line Components and Technologies
Capping: cap types, tightening torque and seal defects
The capping unit is at the end of the line, and all defects it passes are discovered at the warehouse or in the store. Torque setting is the most underestimated procedure on the production floor.
Why torque matters more than speed
An under-tightened cap lets gas and microorganisms through: the product loses carbonation and shelf life. An over-tightened cap strips the thread or deforms the seal — the result is the same, but it is discovered even later.
Tightening torque is set for each bottle-cap pair and checked with a torque meter on a sample from each shift. This is a five-minute procedure that prevents most seal-related complaints.
Magnetic capping heads allow precise and repeatable torque. Spring solutions are cheaper but drift from calibration with wear.
Capping types
| Type | Product | Features |
|---|---|---|
| Screw cap | Water, beverages, oil, chemicals | Magnetic heads, torque control |
| Crown cork | Beer, sparkling, glass | Crimps on the bead, neck geometry is critical |
| Cork or synthetic stopper | Wine | Vacuum unit, often with nitrogen purge |
| Twist-off | Jams, sauces, glass jar | Vacuum in jar after cooling |
| Pump and trigger | Cosmetics, household chemicals | Nozzle orientation, torque control |
| Induction seal | Chemicals, oil, pharma | Membrane under cap, tamper evidence |
Main defect causes
- Wrong torque
- Torque meter check every shift and after each changeover.
- Out-of-spec cap batch
- Incoming dimensional control is mandatory.
- Contaminated neck
- Product drops prevent sealing. Solved by filler valve design.
- Worn chucks
- Scheduled replacement of capping head consumables by runtime.
- Crooked cap feed
- Sorter and feed chute adjustment, cap presence sensor.
FAQ
Is a separate capper needed if there is a triblock?
In a triblock the capper is already integrated and synchronized with the filler. A separate machine is needed for linear layouts or for a second cap type for another format.
How often to replace head seals?
By runtime specified by the manufacturer and unscheduled if the reject rate rises. A set of consumables is included in the spare parts stock from the start.
Can caps of different diameters be used?
Yes, through change parts and sorter adjustment. Changeover time depends on the specific machine design.
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