How the sorter should orient the caps
The sorter disc has the job of feeding the capper with caps always in the correct orientation (thread down, tamper-evidence band up). When an inverted cap slips through the capper feed chute, two problems follow: (1) the head tries to apply the inverted cap and generates a bottle without cap; (2) the cap may stick in the chuck, causing cascading defects on the next cycles.
The sorter usually does this filtering mechanically — by cap geometry (wider at the bottom than at the top) or by the gap between discs. When that filtering fails, there are two dominant causes.
disco-selecionador-tampa-invertida.jpeg
Causes — Cap
| Item | Cause | Solution |
|---|---|---|
| 10.1.1 | Broken bands (cap without tamper-evidence band). | See broken band diagnosis. Without a band, the cap is symmetric and the sorter can't tell orientation. |
| 10.1.2 | Excessive cap concavity. | Adjust the sorter disc for this new condition. When the lot is over, return to the original setup. |
Cause — Capper
| Item | Cause | Solution |
|---|---|---|
| 10.2.1 | Distance between sorter discs too large. | Adjust the gap by removing shims or adjusting the fixation. Check for disc wear — when the assembly is beyond recovery, replace with a factory-calibrated cap sorter. |
Connection to other defects
Inverted caps connect directly to two other failures:
- Broken band — root cause of inversion.
- Bottles without caps — consequence of inversion (next post).
By correcting the inversion at the sorter, you prevent both. Hence the golden rule: whenever a bottle without a cap shows up on the line, audit the chute and the sorter first.
Guide to Cap Application Problems
The 13 most common capper failures — diagnosis, root cause and correction. Free technical material.
Download the full guide →