Optimum results for these seals, combining security with easy-to-peel features, are achieved by making an appropriate choice of lining material and using the correct measure of pressure, heat and time during the induction sealing process. Pressure is needed for the liner to have an even seal to the container rim and this is achieved by the torque heads of the capper when placing the closure onto the filled container.
Heat is applied via a magnetic induction process. This raises the temperature of the seal’s metallic foil element to initiate adhesion of the seal liner with the container rim. Timing is crucial for a successful seal. Timing intervals include the period the closure passes beneath the induction coil and the following cooling period, during which the container must not be subject to any rough handling as it is moved by the conveyor.
Too much pressure (cap-on torque) between the liner and container rim, excessive heat to activate the liner seal surface, or extended dwell time under the induction coil will leave users with a seal that cannot be removed with ease. While too low a level of heat, pressure or time will result in leaks or the ingress of contaminants. Optimal operating window settings for these parameters are normally determined by running trials on the production line under typical conditions.
The choice of liner is also critical to ensuring easy-open packaging and reputable liner manufacturers are constantly developing products to match consumer needs. While there are literally hundreds of different specialist liners available to meet all manner of applications, those liners with an easy-to-grip tab, such as Selig's Lift 'n' Peel™ induction seals, have considerable consumer appeal.
This type of easy-open polyester tab is designed to be ergonomic, flexible and extremely strong, and is engineered specifically to maintain product quality whilst being easy for the consumer to remove. In addition, they can be printed with a customer specific design or branding logo, as well as clear opening instructions in a large font, indicating the position of lift and direction of pull.
An ageing global population is here to stay and the packaging sector must ensure its products constantly evolve to accommodate the needs of the elderly and remain relevant by removing restrictive design. Easily removable seals, such as the Lift ‘n’ Peel™, are very much a part of this process. By selecting the most appropriate lining material and optimising the induction heat sealing process, it is possible to remove the barriers that sub-par packaging can create to ensure it is easy to open while also being totally secure for a positive user experience.