The difference in the disks used on the spindle capping machines manufactured by NPACK is another subject that we have touched upon previously. However, the subject is one which always warrants revisiting, both to educate new packagers and refresh the memory of old packagers. The different colors seen on the disks that tighten screw on type closures are not just for aesthetic purposes, they serve a functional purpose as well.
Spindle cappers are one type of capping machine used to tighten continuous-thread caps. While the most common type of screw-on cap is probably the flat cap found on most bottles of water and popular soft drinks, these caps cover a much wider range of bottles and products. Flip top caps on shampoos, conditioners and similar products are often continuous thread closures. Trigger sprayers found on popular glass cleaners, sports caps found on some drinks and even pump sprayers used on some soaps and sanitizers all use screw-on type caps to seal bottles and protect product.
Spindle capping machines use multiple sets of spinning disks to contact the cap and turn it on the threads in order to create a tight seal. The bottles move down an conveyor and through the matched sets of disks, with each set moving the cap a little farther down the threads, allowing for a consistent, repeatable and reliable seal with each cap tightened. Most spindle cappers run automatically using a cap delivery system that automatically delivers and places the cap on the bottle just before it enters the capping area to be tightened by the disks.
For most of the machines manufactured, the disks on the bottle capper will be yellow. This is not because NPACK like the color yellow, though we admittedly have nothing against it. The disks used on the spindle capper actually come in a number of different colors, but the yellow is the most common because of the hardness of the yellow rubber disks. Yes, rather than making the capping machine look good, the spindle disks are color coded according to the hardness of the rubber used to make the disks.
For most plastic threaded caps, the yellow spindle disks are able to spin and tighten the closures without any harm. However, on rare occasions, one of two things may happen. In some cases, caps may become scratched or marred by the disks. Obviously, a packager does not want to put damaged product on the shelf for consumers, even if that damage is only on the caps and the product is fine! In these cases, if adjustments to the capping machine do not solve the problem, a softer disk may be necessary to achieve a good seal without harming the caps themselves. In other cases, the caps simply may not tighten consistently on to the bottles. Again, if adjustments to the set up of the bottle capper do not solve the problem, a slightly harder rubber may be necessary for the disks to correctly do their job. In either case, a change in the hardness of the disks will also lead to a change in the color of the disks used.
As noted above, if you are experiencing damaged caps while running a spindle capping machine, the first step is to refer to the machine manual and check to ensure that the equipment is properly set up. From a level machine to proper positioning of the disks, there may exist a number of different reasons for inconsistent capping or damaged caps. NPACK technicians can help identify the issue or assist with set up. And in those rare cases where a different durometer of spindle disk is necessary, the NPACK parts department can help find the ideal hardness for the project.