The induction cap sealing process relies on 3 components - pressure, heat and time. Today, I'd like to share a little bit on the first of these three, pressure. Induction sealing is a non-contact process, therefore it requires a source of pressure on the foil inner seal in order to successfully seal your product. This pressure is created by applying application torque on the closure. When properly torqued onto the container, the closure exerts pressure on the foil liner resulting in intimate contact between the foil seal and your container. Add a little heat for a given amount of time and you have a hermetically sealed package.
What's the right amount of torque? Now that's the magic question! A rule of thumb we often use is 1/2 the diameter of the closure in inch-pounds. For example, a 38mm closure should receive approximately 19 inch-pounds of application torque. While this is a good rule of thumb, there is usually a larger range. Three resources you can use to find your range:
- Cap Supplier - your best source for application torque information is your cap supplier; they know their products better than anyone and will be able to provide you with an exact range for your closure
- Enercon's cap ruler - allows you not only to measure cap/bottle diameters easily, but also list suggested application torque ranges (request your free cap ruler today)
- Enercon's web site - we have a page dedicated to suggested cap application torque
Application torque is one of those vital components to the induction sealing process. Too little (or too much) torque and you'll end up with unsealed products. Applying inconsistent application torque will result in inconsistent results. If you can nail down the proper application torque on your package, you'll be well on your way to properly sealed packages every time!