What is Foam Sealing?

Liquid foam sealing and formed-in-place foam gaskets have been used for decades across a range of industries. Simply put, they are a liquid applied substance that then hardens to form the seal.

There are a few different methods of generating these high specification foam seals, Robafoam specialises in a single component foam system which we will focus on as an example. We believe our product and process gives you the best sealant on the market, and in this piece, we are going to discuss some of the benefits of foam sealing and what makes foam sealing so good.

What is foam sealing, foam gasketing, formed-in-place gasketing and formed-in-place foam gasketing?

The standard definition of a foam formed in place gasket or seal is that the seal material being applied is a liquid; this way it can flow into the groove or intimately mate with the surface it has been applied to. Because of this, formed in place foam gaskets can be applied to a wide range of surface finishes, part geometries and can vary in size and shape as it’s applied depending on the flow rate and dispensing rate of the material.

Once on the surface, the liquid then has to undergo some form of curing; this can be heat cured, a two-component chemical reaction or air-cured.

Most of the foam materials being applied (and non-foamed materials) are either thixotropic or have high viscosities which stops them from losing their shape when sat on the surface.

What is the aim of a Foam Gasket?

The aim of using a formed in place seal is to create a truly bespoke seal that is applied directly to the part. This means the sea is bonded onto the part either onto a flat surface or more often, into a groove which ensures that the most intimate seal can be formed and any surface imperfections such as sink within a moulded part or surface scratches on a metal part do not affect the seal performance as the seal will fill the gaps and not just sit on the surface.

Methods of applying foam seals

Depending on the level of accuracy and the performance requirements of the seal, you can apply these seals in two main ways:

Manually Applied Foam Seal Straight from the Cartridge

Foam can be applied straight from the canister, this is a cost-effective answer for many people who are looking for high resistance insulation for home projects. Manufacturers make foam sealing systems easy to use and accessible for this method of application as well, so it is a great solution that comes with an array of benefits. Here are some of the key factors to take into account:

Manually Applied Sealing Foam is Only as Good as the Operator

We have already discussed the great assets of polyurethane foam, and how its properties lend themselves to being a perfect solution for sealant needs. another great benefit is that it can be applied manually, on the other hand though, this means your foam seal is only as good as its operator. To have an effective barrier, you need to have the foam effectively applied to the required areas.

Manually Applied Foam Gaskets are Cheaper than other Solutions

The physical properties of foam types for sealing purposes are a great form of resistance at a lower cost; especially when manually applied. However, as previously mentioned, to get the best application generally you will need some experience.

Good Enough for Low to Mid IP Ratings

When a foam gasket is manually applied, it is good enough for low to mid IP ratings, good for NVH reduction, bonding, potting and cushioning.

Using Robafoam Technology to Robotically Apply Foam Components

Here at Robafoam, we have a tried and tested way to apply a foam gasket effectively compared to other application methods; hence, offering you the best resistance and insulation properties. Here are some key factors about our method:

More Reliable Resistance

For the best repeatability and accuracy, applying a seal by robot ensures the seal is the same every time. Using this method, you can control the seal very accurately, this can allow for tolerances to 1/10th mm which can be important for technical applications.

Better for Large Projects

Perfect for large projects where tooling can be manufactured, leading to high throughput of parts with low numbers of rejects and low downtime.

Top IP Ratings

With a higher degree of accuracy, this is the best way to get top IP ratings and the highest performance for NVH reduction, bonding, potting and cushioning.

Top 5 questions we’re asked about Foam Sealing Materials

What is Polyurethane Foam Sealant?

With less face to face meetings now, we understand that information can be harder to find, so we thought it would be a good time to investigate the sorts of questions we get asked about our unique foam sealing process.

Both the foam material itself and the process in which it is made and applied is unique within the sealing industry and offers many benefits for our customers. However, it also means that sometimes designers and manufacturers have questions about how it could work with their part. Below are the top five questions we get asked at Robafoam.

Top 5 questions we get asked by potential customers

Here are our most commonly asked questions regarding our foam sealant:

What is Polyurethane foam made of?

The material we apply to our customer’s parts is a single component polyurethane material. Launched in 2015, and developed by chemists in the UK, the material is regularly tested and reviewed to enhance its performance.

It is categorised as a 1K technology as it uses a single component that requires no additional chemicals or materials to apply the foam or for it to cure. The material is entrained with compressed air to create the foam and the amount of air used can be adjusted to create a wide range of foam hardness, depending on the requirements of the customer.

What level of IP rating can be achieved with Polyurethane foam?

This is one of the most common questions we are asked. And the answer is that our foam can achieve any IP rating required, as long as its incorporation is considered alongside the design of the part.

Achieving an IP rating is a balance between the compression, hardness, and width of the seal, working with the flexibility, span, and wall thickness of the part. It is therefore very helpful if we work with designers at the early stages of the development of the parts to ensure these requirements are considered.

How long do Polyurethane foams take to cure?

On its own, the material takes seconds to cure when subjected to heat above 80C. We generally use thermal ovens to cure the seals however they can also be moisture cured if required.

The length of time it takes to cure varies due to the substrate of the part and the size of the foam seal that has been applied. To ensure the whole of the seal is cured fully, the part that the seal has been applied to also needs to reach 80C. A metal part would reach this temperature easily due to its thermal conductivity, therefore, reducing the curing time, however, a plastic part takes longer. We refer to this as the heat-sink property of the part material. Generally, it can take anywhere between 2 and 7 minutes for the seal to fully cure.

How long does a polyurethane foam seal last?

Our foam seal has been rigorously tested to ensure it lasts the lifespan of the product that requires the seal. For example, a street lighting has a life span of around 10 years or a car’s warranty guarantees a time frame of around 7+ years.

Naturally, the dynamic forces to which the joint is subjected, along with exposure to more aggressive chemicals can have an impact on the longevity of the seal. Also, the greater level of service requirement (decompressing and recompressing the foam seal) will impact its seal performance over time. And those seals operating at the higher end of its thermal resistance will also play a factor.

Does it stick to all types of parts?

This is a trickier question to answer as it is very much dependent on the substrate that the foam is being applied to. The relationship between the foam material and part surface is key and, in particular, the Dyne value which measures the surface energy of the part surface.

It is not a simple matter of saying that we naturally bond to powder coat surface, for example. As there are many types of coatings with one category.  However, if we find through testing, the material is unable to stick to the substrate, all is not lost. Using atmospheric plasma; more often than not, we are able to change the parts surface energy.

Naturally, not all customers require adhesion and this is something we would consider in our evaluation of a new application. All our robot cells have a plasma system incorporated, meaning this option is never an issue for our customers. Below is a table giving a general “rule of thumb” regarding adhesion to different material types.

Other Frequently Asked Questions

Here are a few more questions that people often ask:

Is Polyurethane foam good insulation?

Polyurethane foam is often used as a foam sealant, the application process means it can be applied to tricky surfaces and areas easily as it takes the form of the environment it’s applied to. As a result, construction has implemented insulating foam sealants as an alternative to traditional sealants. Here are some of the things polyurethane foam can protect against:

Heat Insulation

Polyurethane foam is a great form of thermal insulation. It can easily fill gaps and cracks as the foam will fill any area it is applied to. The spread of the foam will seal any seals and help keep heat in.

Sound Insulation

With spray foams, and their ability to mould to a shape or area, they also insulate against sound. They can help prevent vibration between two surfaces and as a result, can help eliminate unwanted noise.

Water insulation

Again, since polyurethane foam fills gaps and cracks so well, it can be the perfect barrier for water as it stops even the slightest bit of moisture from getting through joints.

Are Polyurethane Foams flammable?

Polyurethane foam is not flammable; however, like most seals, it can only withstand certain levels of heat. For most jobs though, this is no issue as the foam is great for heat insulation.