How Inconsistent Cap Roundness Causes Automatic Capping Machine JamminG

In the aluminum cap packaging industry, we have noticed a very common but easily ignored quality problem. Most incoming quality inspections focus solely on thread size and appearance, while tiny ovality deviations of the cap blank are always left unchecked.

Manual sorting cannot catch deformation smaller than 0.04mm. However, for modern high-speed automatic capping lines running 100–200 caps per minute, these tiny flaws are enough to cause intermittent feeding jams. From our long-term follow-up with end users, such invisible defects usually result in 5%–7% lower packaging output and frequent unexpected machine stops.

The root cause is not poor threading quality. Most ordinary production machines only tune parameters for thread rolling, with no targeted control for blank stress deformation. After continuous high-volume production, accumulated stress slowly distorts the roundness of semi-finished caps.

Based on our years of on-site machine debugging experience, we have optimized the whole-process circular positioning structure for our cap rolling equipment. This structure slowly releases blank internal stress during rolling processing. In actual batch production, it helps stabilize finished cap ovality within 0.03mm.

This subtle but effective improvement avoids irregular feeding resistance on automated lines, helping clients maintain stable continuous packaging operation and reduce unnecessary production losses.