Many different types of materials can be used in gasketing applications, and each material has its own set of characteristics that make it the ideal choice given the application and its operating environment. Some of the most common gasketing materials are open and closed cell foams, rubber, vulcanized fibers, non-asbestos material, cork, plastic, and even metal. Foam and rubber are two of the most commonly used materials when it comes to gasketing applications largely because of their compressibility, resilience, ability to be fabricated into complex shapes, and their shock resistance.
These materials can also be combined with pressure sensitive adhesive (PSA) tape, creating a custom gasket that can be produced to your deliver to your exact specifications and easily installed in any product.
For more information on choosing a PSA tape for your gasketing application, see this guide.
While the choice of material may seem simple, there’s a lot more to consider. What needs to be considered when choosing gasket materials? What’s the difference between rubber and foam gaskets? In what situations should you use each material in your application?
Consider the environment where the gasket is being used, as it’s the most likely reason why your gasket will fail, underperform, or lose its effectiveness as time goes by. Choosing a material that effectively performs based on the environmental conditions it will be exposed to is the number one way to ensure longevity, durability, and performance.
Which environmental impact gasket materials?
Temperature: every material reacts differently to temperature changes, which is why you’ll find standard operating temperatures with each material you consider. Heat causes many materials to expand and then deteriorate, while colder temperatures cause them to contract and to become rigid. Understanding the effects of temperature is particularly important in gasketing, as subjecting materials to temperatures outside of their operating range even for a short time can cause the gasket to fail.
UV Exposure: UV light can degrade some material faster than others, causing them to become brittle and break, tear, etc. Be aware of how resistant to UV light your materials are and how much they will be exposed to while in use.
Exposure to Moisture, Chemicals, and Solvents: as with UV light, some materials will degrade and break down when exposed to moisture, water, or certain types of chemicals or solvents.
ESD/EMI Protection: some gasketing applications require that electronic equipment be protected against electrostatic discharges and electromagnetic interference, so it becomes necessary to use a material that can shield against them.
Liquid or Gas: will the gasket be responsible for stopping liquid or gas from passing?
It is also important to consider space gasket must fill, the resilience needed in application, and the force applied in use. The gasket thickness is a critical factor in determining its effectiveness. Meanwhile, depending on the actual in use requirements determining the right compression properties will ensure that the gasket performs at the chosen thickness.
Gasket Thickness: choosing the right material thickness helps ensure your gasket seals properly. Due to cost and performance considerations, specifying thinner materials is optimal. When gaskets are too thick, they are prone to performance issues and introduce a higher probability of generating leak paths. At the same time, when gaskets are too thin, they are unable to reliably seal. Substrate thickness, design space to seal, and gasket material compression characteristics will help determine the optimal design thickness required.
Compression Set: when force is applied to flexible material it compresses. Compression set is the percentage to which the material fails to return to its original height. The higher the number the less a material will return to its original height after compression. The lower the number, the more resilient the material. When designing a gasket, it is important to consider the compression set requirements. In applications with permanent compression, like refrigerator boxes, higher compression set materials may be right. Alternatively, for electrical enclosure door seals, a highly resilient and low compression set material may be required. Typically, the more need there is for resealing a gasket, the lower the compression set should be.
Compression Deflection: the force with which the gasket material pushes back when under force is called compression deflection. Positive material force creates the positive seal required for gasketing. Material compression deflection must be enough to seal given the variation caused by tolerance stack up. but not so much as to necessitate leak paths.
The gasket material you choose depends on the specific gasket application requirements. These are some of the more common gasket material options.
Common open cell foams can be divided into two primary categories: low density polyurethane and high-density micro cellular polyurethane. Low density polyurethane foams (like reticulated foam) are more suited towards filtration applications because of their breathability, but their breathability allows them to be used as door gaskets, helping to cut down on light, sound, moisture, and air infiltration.
High density polyurethane foam has a lot of features that make it an ideal choice for gasketing:
High compression set resistance
Large operating temperature—it tolerates extreme heat and cold
Non-corrosive and strong chemical resistance
Good for sealing, vibration insulation, and sound dampening
In all, it can be an effective material for long-term gasketing applications. 3M’s newly introduced Aero Isoloss provides a wide variety of moduli and densities to choose from.
Because closed cell foams are commonly made from plastics and flexible rubbers, they make great water and vapor barriers in gasketing applications. There are many different types of closed cell foams that can be used, depending on the operating environment (find out more about each foam option and its applications by visiting their product pages).
Solid Rubber Gaskets
Solid rubber materials are durable materials made from a wide array of polymeric elastomers. They are ideal liquid seals that can operate in a wide range of conditions, depending on the material you choose. While more durable than foams, their hardness provides less forgiveness in gasket design. There are many different types of solid rubber gasket options.