Introduction to IHS Seals - When to Use Them (and When Not To)

Induction Heat Sealing is a way of hermetically sealing a laminated disc to the top of a plastic or glass container, after the container has been filled. Done right, it provides tamper evidence, prevents leaks, preserves freshness, and enhances brand.

Induction Heat Sealing - What Is It?

Induction Heat Sealing (IHS) is a way of hermetically sealing a laminated disc to the top of plastic or glass containers, after the container has been filled. Done right, it provides tamper evidence, prevents leaks, preserves freshness, and enhances brand.

IHS Induction Heat Seal Process Diagram
[Diagram courtesy of Selig Group.]

Induction seals are typically multi-layer laminate discs including a heat-sealable foil laminate. The discs are usually pre-inserted into screw closures, which are then screwed onto the filled pack on the production line to the correct torque, before passing through a machine where it spends a pre-determined length of time under a head with an induction coil, creating the right amount of heat to seal the laminated disc onto the top surface of the container neck. The correct Pressure, Heat and Time are the three key elements required for a successful seal.

The disc usually has a compressible foam pad at the top - so when the end user unscrews the lid, this foam seal remains in the lid. They then peel off the foil layer which is sealed onto the container, and when they re-close the screw lid, the foam provides the necessary seal for protection during the remainder of the product's life.

Where is it Used?

E-commerce giants like Amazon have been encouraging the use of IHS seals in recent years, within the standards they are setting out as part of their move towards safer and more sustainable transport packaging for e-commerce parcel deliveries.

Clearly, IHS sealing has been around for a lot longer than this though - typically, it's used in anywhere where tamper evidence is important, along with preserving freshness and even reducing pilfering. It can also ensure leak prevention, although a well-designed closure and container combination shouldn't ever leak.

For specific instances, you might think nutrition, jars of supplement pills or tablets, perhaps some hot-filled balms or creams, and in other industries, this is commonplace in food and drink - such as milk, fresh juices, or processed honey and spreads.

What Container Materials is it Relevant For?

IHS sealing can actually be used on plastic - for example PET, PP and HDPE - and also glass containers. The adhesion level and the best type of seal to use will vary, depending on the type of material involved. For more details, please contact us.

Other variables can include the type of removal - e.g. whether an easy peel is important, such as providing a pull-tab to help the end-user remove the seal.

Products this case study features:

Airless

Typical IHS Liner Seal Diagram

This Lift n Peel seal from Selig demonstrates some of the complexity which can be involved in the laminated layers of an IHS liner.

IHS Lined Closures

View a selection of Richmond's range of IHS closures. Discuss your specific requirements with the team.

View IHS Lined Closures

So Far, So Good - So Why is Everyone Not Using IHS?

Firstly, it could add expense. If you have proved that, for example, a jar with a simple EPE-lined lid already does a successful job of protecting your product, then replacing this with IHS sealing means using a more expensive type of cap, and adding additional processes and time into your filling process.

It also adds complexity. As we have hinted at above, there are a number of variables - and we have given a high-level overview of the factors required for a successful seal. When it's working, it really is great; when something fails, there can be an involved diagnostic process involved to pinpoint the causes, eliminate them, and get the process back on track.

There are technical limitations, including reduced effectiveness when using some closure materials, less-common shapes, or very high-density closures. There can also be limitations of the liner that is retained in the closure after the first opening - careful testing is required to ensure the best solution.

There can also be minimum order quantities of many thousand pieces, so depending on your project size, testing and compatibility can prove costly. More specific or unusual material requirements could easily result in a more customised liner specification, which could in turn increase minimum production runs further.

Conclusion

With careful forward planning and research into specifications, induction heat sealing is a great idea for quite a number of applications. It can enhance brand, ensure tamper evidence, and improve maintenance of freshness. As always, chat to our experts to ensure you have covered the bases, including looking into the full range of seal options for your specific application.