Tightening Continuous Thread Caps - Spindle Cappers

Continuous thread closures, also often referred to as screw-on caps, exist over a wide range of industries. Beverages such as bottled water and soft drinks typically use a continuous thread flat cap that can be twisted by the consumer for easy access to the drink. Screw-on type closures, however, can take many different forms other than a simple flat cap. Sports caps, flip-top lids, pumps and even trigger sprayers will often screw on and off of products ranging from soaps and shampoos to household cleaners, motor oil and more.

One type of capping machine used to automatically seal bottles using screw-on type closures is the automatic spindle capper. Analyzing the different components of this automatic packaging machine will help to understand how the spindle capper continuously and reliably tightens threaded caps with almost no operator interaction.

An automatic spindle capper will consist not only of the capping machine, but also an automatic cap delivery system. The delivery system can use a vibratory bowl, a cap elevator, or a combination of these machines to ensure correctly oriented caps are delivered to the bottles prior to the tightening process. An operator of an automated line will need to provide bulk caps to the sorting machine. These caps can simply be dumped into a hopper at the beginning of production and, depending on the work day and the speed, may need to be replenished from time to time.

Once the hopper is running and the capper is running, the caps will either travel up a flighted conveyor belt or around the rim of the vibratory bowl. Each delivery system allows caps that are oriented incorrectly to fall back into the hopper to start the journey again, meaning only caps that will be placed correctly on bottles will reach the capping machine.

From the bowl or elevator, the cap is delivered to a cap chute. The chute holds the correctly oriented caps in place to be delivered to the bottle as it passes by on a power conveyor. At the end of the chute each cap will be held be a set of fingers. As the bottle passes and catches the edge of the cap, the fingers release the cap, and the bottle and cap combination will continue down the conveyor to enter the capping machine.

The spindle capper itself will include different components to keep the bottle and cap stable and ensure consistent and reliable tightening. A stabilizer bar will typically press down on the cap to avoid cross-threading or falling caps. The stabilizer bar may look different for different projects depending on the closures being used for any given project. Bottles will be guided through the spindle capper using gripper belts to stop vibrations, tipping or other issues that could lead to inconsistent capping. For tall or uniquely shaped bottles, double gripper belts may be used for added stability.

The tightening itself takes place as the bottle and cap move through the capping machine on the power conveyor, traveling through several sets of spinning disks that will thread the cap onto the bottle. On most spindle capping machines, the last set of spindles will include clutches that allow the packager to fine tune the amount of torque that will be applied during the capping process.

In addition to adding bulk caps to the automatic delivery system, operators will set up the spindle capper prior to production for the bottle and cap to be prepared. This process normally consists of simple hand crank and knob adjustments to position the gripper belts and spindle disks correctly. However, once the machine is set up, the operator is free to engage in other production processes, simply observing the machine itself or the packaging line as a whole to ensure proper performance. The spindle capper can run continuously throughout the production day as this machine tightens caps without stopping or slowing the conveyor belt to complete the process.

To learn more about the machine, click to the Spindle Capper page on the Liquid Packaging Solutions website, or contact LPS to discuss your capping project today.