Gaskets play a crucial role in ensuring the safety and functionality of countless devices across various industries. From providing waterproofing to maintaining the integrity of electronic enclosures, the right gasket selection can make a significant difference.
This blog post will explore why gaskets are necessary, what materials are used, common applications, gaskets versus O-rings, and design considerations to help you choose the best gasket for your needs.
Why Are Gaskets Needed?
Gaskets are essential components that serve as seals between two non-moving, static surfaces, preventing the leakage of fluids or gases. Their primary function is filling the space between mating surfaces and compensating for any irregularities to create a reliable seal.
Gaskets are critical in helping devices meet specific IP (Ingress Protection) ratings, which define the level of protection against the intrusion of water, dust, and other foreign bodies. Gaskets are pivotal in achieving such ratings by forming watertight seals that prevent moisture ingress, thus ensuring the longevity and performance of the device. Gaskets can also be used in cases where anti-vibration or mounting assistance is required.
Gaskets at use in a heavy-duty application.
Gasket Materials
Selecting the right material for a gasket is crucial for ensuring optimal performance and longevity. Based on the environment and application your gasket will be placed in, should determine what material it should be constructed from. Here are some common materials used in gaskets:
Rubber Gaskets
Rubber gaskets are highly flexible and resilient, making them suitable for applications requiring frequent assembly and disassembly. They offer excellent resistance to water, oils, and chemicals, making them ideal for various industrial applications. Rubber gaskets also offer superior compression sets compared to foam gaskets, meaning that after years of use, the gasket is less likely to suffer any permanent deformation. These gaskets are commonly made through the means of injection molding, though they can be die-cut to specific shapes and sizes for custom designs.
Foam Gaskets
Foam gaskets provide excellent cushioning and insulation properties. They are lightweight and can conform to irregular surfaces, making them suitable for applications where vibration damping, and thermal insulation are required. Foam gaskets come in two main types: open-cell and closed-cell forms. Open-cell gaskets are light, flexible, and adaptable to unique and uneven profiles. Closed-cell foam is denser and firmer, which provides a higher resistance to outdoor elements. Like rubber gaskets, foam gaskets can be molded into their final form, or cut from sheets to their desired shape and size.
Foam gasket used in an enclosure.
Metal Gaskets
Metal gaskets are used in high-pressure and high-temperature applications where rubber or foam would fail. They offer superior strength and durability, making them ideal for use in harsh environments such as automotive and aerospace industries. Metal gaskets are also used best in high-pressure situations, as they are more suited for handling greater amounts of psi compared to a rubber or foam gasket. These gaskets are made from a single piece of metal that is cut to their final size.
Where Gaskets Are Used
Gaskets are employed in a wide range of applications across different industries, such as in machinery, food processing, electrical equipment, pumps, cars, and much more. Any piece of equipment that needs to keep out foreign liquids or dust from the inside should require a gasket or some type of seal-forming material. Here are some uses of gaskets that Epec deals with frequently:
Enclosures
Gaskets are often placed between the body and lid of an enclosure to prevent the ingress of dust, moisture, and other contaminants. This is especially important in outdoor or harsh environments where the device is exposed to the elements. Some examples you could see are electrical outlet boxes, controllers, flood lights, cable splitters, and more. All these types of enclosures will typically advertise some type of IP rating that is reinforced by the gasket included in the enclosure.
Silicone gaskets in an enclosure.
Membrane Switches
In electronic devices, gaskets are used in conjunction with membrane switches to provide a tactile feel and ensure environmental protection. They help maintain the integrity of the switch by preventing contaminants from entering the device. As membrane switches are typically connected directly to a PCBA or electrical component of a device, moisture or dust mustn't breach the seal of the membrane to cause these vital parts to fail.
Exterior Connectors
Gaskets are used in exterior connectors to provide a watertight seal, preventing moisture from penetrating the connection and causing electrical failures. This is critical in automotive and marine applications where exposure to water is common. These gaskets tend to be much smaller and are typically designed with O-rings in mind due to their size and fit.
Flat Gaskets or O-Rings
The choice and structure of gaskets depend on the application requirements and the environment in which the device operates. Not all equipment has the space to fit an O-ring, or some devices need more than just a flat gasket to provide adequate sealing. Here is a brief comparison of the two:
Flat Gaskets
Flat gaskets, often referred to as sheet gaskets, are made from flat materials such as rubber, foam, or metal. They are commonly used in applications where the sealing surfaces are flat and parallel. These gaskets are versatile and can be easily cut to fit complex shapes, often used in many custom designs where mating surfaces are unique.
Example of flat gaskets.
O-Rings
O-ring gaskets are circular, torus-shaped seals commonly used in dynamic applications where there is movement between parts. They are designed to fit into a groove and are compressed during assembly, creating a seal that prevents leaks. O-rings are often used in hydraulic and pneumatic systems due to their excellent sealing capabilities. O-ring material is limited to flexible materials, such as silicone, neoprene, or any type of rubber or foam material.
Designing with a Gasket in Mind
When designing an engineered product that incorporates gaskets, several factors must be considered to ensure optimal performance and reliability. Even if a single factor is anything less than sufficient, the integrity of the seal may be compromised. Gasket design should never be skimped on, as an improper gasket design can be the difference between a device becoming certified and reaching the market, and never making it out of the R&D lab.
Space for Expansion
It is essential to allocate enough space for the gasket to expand when compressed. Over-compression can lead to gasket failure, reducing its effectiveness and potentially compromising the seal. Thin enough gaskets can be placed between two flat mating surfaces, or inside a cutout in one of the surfaces that is compressed with the mating surface once pressed together. Once compressed, the gasket will expand and fill in any open space left between the two surfaces.
Interference Fit
The amount of interference, or compression, required for a gasket to form an effective seal depends on the material and application. Designers must carefully calculate the necessary interference to ensure a proper seal without over-stressing the gasket. Foam gaskets require higher compression to form a watertight seal compared to rubber gaskets, though it becomes much easier to compress when dealing with a foam gasket.
Complete Compression
Ensuring complete compression of the gasket across the entire sealing surface is vital for preventing leaks. Uneven compression can lead to gaps and potential points of failure, reducing the overall effectiveness of the seal. To create an even seal, it is recommended to provide adequate compression across the perimeter of the gasket or increase the rigidity of the mating surfaces to prevent any bowing once the two surfaces are mated together.
Summary
Gaskets are essential components that play a vital role in ensuring the safety, performance, and longevity of devices across various industries. By understanding the different types of gaskets, materials, and design considerations, you can make informed decisions when selecting the right gasket for your application. Whether you need a simple flat gasket or a custom solution, choosing the appropriate gasket can help you achieve the desired level of protection and performance.
