Chuck capping machines provide a second option for tightening the most popular type of closure, the continuous thread, or screw-on, type cap. We have already discussed the spindle capping machine as a popular choice for tightening these types of caps, so why two different pieces of machinery to perform the same task? As we discussed before, continuous thread screw caps vary greatly, from simple flat caps to flip-tops, trigger sprayers, sports caps, pumps and more. In addition, different packagers have different demands that must be met on any given product. For some cap variations and some production demands, the chuck capper will be a more convenient and efficient solution!
Automatic chuck capping machines typically work with a starwheel type indexing system. In general terms, a starwheel is simply a turning wheel with notches cut to allow bottles to fit within the wheel. The starwheel turns to allow the container to acquire a cap, then positions the containers under the capping heads. For this reason, automatic chuck cappers are normally found on monoblock machines that include a screw-on capping station and on systems that are handling smaller containers such as vials or tubes, to assist in keeping these containers stable through the process. Overall, the chuck capper is the second most popular automatic machine for continuous thread closures, after the automatic spindle capper.
Semi-automatic machines tell a different story, however. While tabletop and semi-automatic spindle cappers do exist, the semi-automatic chuck capping options usually provide better options for those packagers with lower production. Semi-automatic chuck cappers can be manufactured as handheld, tabletop or portable frame machines. Each requires an operator to hand place the cap, while the tabletop models also require placement of the bottle under the capping head. The portability of these machines can allow for greater speed and efficiency, but also offer the benefit of consistent and reliable tightening from cap to cap, something that's not easy to achieve when trying to cap by hand. Handheld chuck cappers can also allow for a capping station, where product can be accumulated and capped in bulk by a single laborer.
Chuck cappers will normally use a steel chuck with a rubber insert, lowering over the cap to apply torque until the bottle is sealed and the closure is tight. While each chuck and insert can handle a range of cap sizes, different chucks and inserts may be necessary when both small and large caps are used at the same facility. Custom chucks and inserts can also be manufactured to handle different types of closures, such as sports caps. To learn more about the different options, visit the Chuck Capper page of the NPACK website.