The essentials for a good induction sealing

This article deals with the practical application of the induction system.

The experience of Cap Sealing Products professionals in the field of induction sealing allows us to have a comprehensive record of the problems encountered by some of our customers in the application of induction sealing of their containers.

A good induction sealing requires three basic elements:

  • The container-stopper assembly
  • The induction liner
  • The induction sealing

First of all, we will deal with the possible problems that may result from the container-stopper assembly. The criteria to choose a particular type of container usually bear no relation to the adaptability to the induction sealing system. This is why often problems arise when trying to make a seal on a container that is not intended for it. Therefore, if a company expects its product to receive a quality and safety seal, such as an induction seal, we advise it to include the ability of the container to be induction sealed among the search requirements of the appropriate container.

The usual problems that appear when the container-stopper assembly does not adapt well to induction sealing are the following ones, among others:

   a. The stopper does not exert enough pressure against the contanier mouth.

   b. The stopper has an interior design -e.g. an inner cone- that is incompatible with an induction liner.

   c. The container mouth is not completely flat or has irregularities.

All of them have a solution, more or less complicated, the cost of which must be assessed.

Secondly, we have the induction liner. This is the element that will allow us to close the container tightly. Therefore, the most suitable material for this must be selected taking into account the container material and content, as we have already explained in previous articles in this blog. At this point, we would like to add the need to assess, as a solution to problems 1.a and 1.c, the use of a thicker material. The material thickness may help us solve the problem of the contact between the elements. If this is not the case, we'll have to find a seal or FOAM to help us with that.

Finally, we have the possible problems in the execution of the induction sealing on the closed container with the liner on it. With any of the induction sealers we use, whether automatic or manual, we must take the following into account:

  • The distance between the sealer head and the container mouth.
  • Power and time.
  • Wave centrality.

In terms of distance, it should be as small as possible. Regarding the centrality of the wave, we must take into account how the induction wave is emitted to understand that the more centred the container is with respect to the emission of the wave, the better the sealing will be. And with regard to power and time, we recommend carrying out tests from lowest to highest -both power and time- to adjust and adapt the power to each type of container until a perfect seal is verified. If they are too high, a burning smell is noticed or the liners simply do not stick to the mouth.

Beyond these three large blocks of potential problems, there are other types of problems related to the packaging of the product. In the case of a very fast or aggressive automatic packaging, it could leave traces of the contents in the mouth of the container and make it difficult to seal correctly.