According to bottle cap manufacturers who have processed thousands of different bottles and caps, capping is actually one of the most difficult parts of the bottling process.

Key factors to consider for better bottle capping results are:

Choosing the right type of capping machine

Inline capping machine: This machine has the benefit of being lower cost, requiring no part changes, and can handle a wide range of caps including trigger sprayers (hand placed). The main problem with this machine is that there are bottles and caps that tend to have thread cuts, difficult caps and bottles will have more trouble on a palletizer than a pick and place machine. Most companies run this machine up to 100 bottles/minute but some can run up to 250 bottles/minute (depending on the bottle and cap design).

Chuck cap pick and place: This machine works better on most containers and caps because the cap is transferred to the chuck and once on the chuck, it is placed directly onto the container. If you choose a cap with a bottle, you have the threads of the container in different random places, so if the tolerances or design are a little tight or unstable, you will have cross threaded caps.

This type of machine works well but is expensive and requires parts to be changed for each bottle and the additional cap adds to the already high cost.

For speeds above 200 bottles/minute it is the only viable solution

Bottle Cap Thread Design

Cap Design: Cap design is important, before committing or buying in bulk make sure everything has been machine tested in the production area. There are projects where one bottle with one cap has 5% of the cap having a horizontal thread and another design, the same size, has 0.2% of the cap having a thread

Bottle shape as well as tolerances are also important, especially with glass bottles. Also there are designs where the thread on the bottle starts at the top edge and others have a small gap, on an inline machine this makes a big difference because when selecting the cap, if there is a gap the cap can sit properly before the thread starts.

Each bottle and cap needs to be examined, researched and tested to ensure that it will function properly at the required speed, torque and consistency.