Spindle Capping Machines and Wheel Color
Spindle capping machines, both tabletop and automatic, will use a set or sets of matching spindle wheels to tighten screw on type caps onto bottles and other containers. If you are familiar with spindle cappers, you may have noticed that the wheels used to tighten the caps may vary in color. The reason for the different colors goes beyond personal preference or aesthetic value, and different colors will work better for different projects based on the container and cap used for the project.
Before we explain the significance of the spindle wheel colors, let's take a look at how the spindle capper works. An automatic spindle capper will have caps delivered to the bottles via a chute (the semi-automatic versions will require an operator to place the caps). Once the cap is introduced to the bottle, it must be screwed down over the existing threads. On an automatic spindle capping machine, the bottle and cap are held steady as they move on a power conveyor through the matched sets of spindle wheels mentioned above. A typical spindle capper will have four sets of these wheels. As the bottle and cap pass by the wheels, each set will contact the cap at a precise location, using the spinning motion of the wheels to tighten the cap on the threads. For this reason, each set of spindles may sit slightly lower than the previous set, as the cap will lower when being tightened. It is this contact with the cap, along with the sturdiness of the cap and bottle, that require different colors of spindle wheels for different projects.
Each color spindle wheel used at NPACK will correspond to a specific durometer. Durometer refers to the hardness of the spindle wheel and, though more than one durometer scale exists, it generally runs from 0 to 100, with lower durometers being softer and higher durometers harder. Most spindle capping machines will use a wheel with a durometer between 45 and 60, soft enough to not mar the cap or damage the bottle, but hard enough to maintain a useful working life. However, certain applications will require wheels outside of the typical range.
Soft caps or non-rigid bottles may require a lower durometer to avoid scuffing the surface of the cap or crushing or collapsing the top of the bottle. The advantage is the ability to use unique and cost-efficient packaging materials. The disadvantage is that these softer durometer wheels may tend to wear more quickly than others, thus requiring more frequent replacement. On the other hand, some cap and bottle combinations may include a ridge on the outside of the neck. The cap must be tightened over this ridge and a higher durometer disk may assist in these situations. Each new project may require some trial and error during the manufacturing process to determine which durometer of wheel will result in a consistent and reliable tightening, without causing damage to the bottle or cap and without requiring constant replacement of the wheels.
NPACK carries four spindle wheels in stock at our LaPorte, Indiana plant. These range from red disks at a durometer of 45 to gray discs at a durometer of 70. Custom spindle wheels can be ordered for projects that require extremely soft or extremely hard wheels. For more information on spindle cappers or the wheels used on the machines, browse the NPACK website or call our offices to speak with a Packaging Specialist.