This article will take an in depth look at gasket materials.
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Gasket materials are the critical element in the manufacture of gaskets and determine the type of function of a gasket as well as the conditions under which it can be used. The purpose of gaskets is to prevent leakage, seal connections, and block contaminants from entering a critical process.
Pressure and temperature are crucial factors in selecting gasket materials and their compatibility with an application. Choosing the right material ensures that the process operates properly and efficiently, minimizing the need for maintenance or repairs.
The different materials are going to be discussed in the succeeding sections.
When selecting a gasket material or designing a custom gasket, there are numerous options available. Some of the most common categories of gasket materials include:
Solid materials are often used as an alternative to sponge materials for gaskets. They offer greater durability and a longer lifespan, with solid gaskets potentially lasting twice as long as those made from sponge materials. Additionally, solid materials can endure higher compression forces than sponge materials, making them ideal for applications that require handling significant compression.
Forming processes such as waterjet cutting, die cutting, and CNC cutting can be used to form solid materials into gaskets. These solid materials have the capabilities of being three dimensionally molded.
Some of the solid materials used in forming gaskets include:
Gaskets made from solid silicone are mainly used in outdoor applications where environmental conditions are less critical. They are ideal for scenarios requiring resistance to extreme temperatures, such as applications exposed to sunlight that might otherwise cause degradation.
Gaskets made from fluorosilicone are suitable for the same conditions as silicone, but they also offer superior chemical resistance. With their ability to resist fuels, oils, and extreme temperatures, fluorosilicone gaskets are particularly well-suited for fuel delivery applications in the automotive and aerospace industries. Due to these added advantages, fluorosilicone is more expensive than silicone.
Nitrile gaskets are designed for industrial applications where environmental extremes and high wear are factors. Nitrile is a robust and durable material that resists chemicals such as oils and fuels. Additionally, some versions of nitrile are suitable for use in food and agricultural applications.
Neoprene gaskets are more cost-effective than fluorosilicone and silicone. They are ideal for applications requiring resistance to liquids like oil and water. Neoprene also offers high resilience and elasticity, allowing it to withstand elongation and tearing better than silicones. Additionally, it has good resistance to fatigue and abrasion.
Gaskets made from Peroxide Cured EPDM They are widely used in rubbers that offer excellent resistance to weather, water, ozone, and UV exposure. Peroxide-cured EPDM, in particular, benefits from heat stability, making it resistant to steam and extreme temperatures. It is generally less expensive than silicone for many applications. However, peroxide-cured EPDM is not ideal for use in applications that are exposed to oil.
Butyl is a synthetic rubber known for its resistance to chemicals and oils. It effectively resists moisture and prevents gases from escaping. Butyl is commonly used in medical and aerospace applications.
Fluoroelastomer is the premium choice among solid materials, offering a combination of benefits that surpass those of other solid materials. It provides excellent resistance to chemicals and extreme temperatures. However, it is more expensive than other solid materials. Fluoroelastomer is primarily used in the aerospace industry, where these properties are essential.
Fluorocarbon gaskets feature a flat cross-section and are reusable for non-critical applications. They are commonly used in situations that require frequent reassembly. Fluorocarbon gaskets serve as an alternative to copper gaskets and are used to seal conflat flanges. However, they are not suitable for high-temperature applications, as they lose strength at elevated temperatures.
Gaskets made from sponge materials are typically used for applications with low compressional forces. Sponge materials are chosen when:
Sponge materials reduce the impact of compressional forces on housings. They are often preferred over solid materials because of their UL flame ratings. For example, silicone sponge with a UL94V-0 flame rating is more readily available than solid silicone with the same rating.
For applications requiring compressible and soft materials, silicone sponges are an ideal choice for padding and gasketing. They offer excellent resistance to extreme temperatures, making them well-suited for outdoor use. Their closed-cell structure prevents water absorption and provides a superior compression set. Among silicone materials, silicone sponge has the longest lifespan and is available in extra firm, firm, medium, and soft densities.
For applications that need a flexible and soft material, neoprene blend is an excellent choice for gaskets. It is a more cost-effective option compared to solid rubber and many other sponge materials. Neoprene blend is used for shock absorption, weatherstripping, thermal barriers, and basic sealing in various industries. Its closed-cell structure prevents water absorption. Neoprene sponge is available in extra firm, firm, medium, and soft densities.
EPDM sponge offers similar benefits to neoprene blend, but with greater resistance to ozone, making it ideal for environments where ozone exposure is a concern. As a result, EPDM sponge is more expensive than neoprene blend.
Foam materials, like sponge materials, are recommended for applications requiring low compressional forces. However, they offer even lower compressional resistance compared to sponge materials. Foams are generally more cost-effective than solid or sponge materials and are used to create basic seals between ducts and primary air. They do not provide a robust environmental seal and are best suited for simple sealing needs rather than critical outdoor applications.
Cellular silicone foams offer exceptional temperature resistance and are used in applications requiring cushioning, sealing, vibration dampening, and insulation. They are available in six varieties, ranging from ultra-soft to extra-firm.
Filter foams are custom-designed to filter out dust while allowing air to flow in and out of the system. They are primarily used in electronic applications where dust is undesirable.
Polyurethane foams Polyurethane foams are widely used for gasketing, energy absorption, and sealing. They are generally more affordable than silicone foams and have a low compression set. Polyurethane foams come in various densities and firmness levels within each formulation.
Polyolefin is a cost-effective material for basic gasket making. It is commonly used as a space filler to prevent two sides of a part from making contact.
Form-in-place gaskets are often used when a very small gasket is required, as these small gaskets can be challenging to die-cut and assemble. Due to their delicate nature, managing and assembling these tiny gaskets can be time-consuming and labor-intensive. In such cases, form-in-place gaskets are chosen to reduce assembly costs. The gasket material is dispensed directly into the unit and then cured. Form-in-place (FIP) materials are commonly used in electronic devices due to their suitability for small sizes.
Silicone sealants and adhesives cure when exposed to ambient humidity. They offer excellent sealing properties and perform well under various ozone, weather, and compression conditions, as well as provide electrical insulation. Silicone sealant can be applied to overhead, vertical, and horizontal surfaces, depending on its viscosity.
When uncured, silicone can adhere to small objects as it sets. In form-in-place (FIP) applications, silicone offers excellent high-temperature performance but has limited flexibility at low temperatures. Its wide availability makes it suitable for a diverse range of applications.
UV materials are used when lead time and production speed are critical. Unlike silicone, UV materials require minimal curing time after dispensing, which allows for faster turnaround. They are preferred in high-volume and high-throughput production environments.
EMI materials are the most commonly used form-in-place (FIP) gaskets for a range of applications. They are well-suited for applications requiring precise and small gaskets, as they effectively meet the needs of EMI shielding. These materials can provide shielding between two gasket sides and are commonly used in satellites, aerospace, and test equipment.
This involves using EMI materials to shield between the two areas of a part or product.
Silicone extrusions combine two types of gaskets—EMI shielding and environmental sealing—into a single product. They feature a thin, electrically conductive shield co-extruded onto a silicone rubber base. These extrusions are ideal for fitting gaskets into grooves. If the groove is too small for extrusion, form-in-place (FIP) dispensing is a better option. Extrusions typically offer lower compression force because they are softer compared to FIP dispensing.
EMI shielding silicone products are conductive due to fillers like nickel, copper, or aluminum. They are highly flexible and adaptable to various designs and sizes. However, they are not ideal for harsh environments, such as exposure to sunlight or caustic chemicals, as these conditions can compromise their shielding and sealing effectiveness. Consequently, they are most commonly used for connector gaskets or in printed circuit boards and electronics.
These materials are used to dissipate heat from components. The choice of thermal interface material depends on the power output over time. Silicone is commonly used for this purpose due to its high temperature resistance. It's important to select a material with the right thermal conductivity to effectively dissipate heat. Generally, higher heat dissipation requires more expensive materials. Additionally, like fluorosilicone, silicone materials may include cloth inserts to improve tear resistance.
Among the many gasket materials available, some are more frequently used due to their distinctive characteristics that make them well-suited for specific applications. These include:
These materials are lightweight and stable, with strong resistance to water penetration. They offer good compressibility, minimal lateral flow, and high resistance to oil. Cork is durable, resistant to wear, and unaffected by high temperatures.
These materials combine granulated cork with synthetic rubber polymers, offering the high resilience and flexibility of rubber along with the compressibility of cork. The rubber provides chemical compatibility, sealant properties, and resistance to weather conditions and acids. A variety of rubber gasket materials are available to meet specific chemical resistance needs.
These materials are available in sponge, foam, or solid forms. Regardless of their state, they share characteristics such as stability at high temperatures, general inertness, and resilience. Some of the benefits of silicone include
However, the most common drawback of silicone is that it is not best suited for numerous hydrocarbons and steam.
Natural rubber offers excellent recovery properties and strong resistance to most inorganic salts, alkalis, and mild acids. However, it is unsuitable for use with oils and solvents and does not perform well when exposed to ozone, oxygen, or sunlight.
One of the special properties of natural rubber gaskets is its resistance to the effects of ultraviolet light, which makes them ideal for outdoor use.
Urethanes are known for their excellent aging and abrasion resistance, although they are not ideal for extreme temperatures. Key characteristics of urethanes include:
This material offers excellent resistance to UV light and ozone, with good tear strength and strong resilience. However, it can be easily damaged by petroleum-based fuels. Key characteristics include:
As previously discussed, various gasket materials are available in the industry, each designed to meet specific criteria. The formulations and grades of these materials can be derived from different substances to suit diverse applications.
The formulations and grades of rubber can be tailored for a wide range of applications, depending on the operating and environmental conditions.
Some of the materials used in the formulations and grades include:
These materials are used in molding processes such as transfer molding, compression molding, and injection molding to create gaskets in various sizes and shapes.
Some of the materials used in the formulations and grades include:
This has cells that are separated fully from the other surrounding cells in order to prevent fluid intrusion.
Closed-cell sponge rubbers are available in densities that range from soft, medium to hard. Some of the materials used in the formulations and grades include:
This material features interconnected cells that allow liquids, gases, and other fluids to pass through. Open-cell sponge rubbers come in five density levels, ranging from soft to extra firm.
Some of the materials used in the formulations and grades include:
These materials are composed of non-asbestos fibers, such as aramid or fiberglass, combined with rubber. This formulation enhances their performance under pressure and temperature conditions.
Some of the materials used in the formulations and grades include:
Cork offers high flexibility and compressibility. When combined with rubber materials like neoprene or nitrile, it creates a gasket that is resistant to solvents, oils, and fuels.
Some of the materials used in the formulations and grades include:
These materials do not have electrical conductivity and are used in electrical applications.
Some of the materials used in the formulations and grades include:
These materials are used to protect electronic and electrical devices from radio frequency and electromagnetic interference.
Some of the materials used in the formulations and grades include:
Fiber materials encompass a range of types, including insulating fiber, cellulose fiber, synthetic fiber, and vegetable fiber.
Some of the materials used in the formulations and grades include:
These are all the materials formed by gas trapped within separate or interconnected cells in a solid or liquid.
Some of the materials used in the formulations and grades include:
This is a material based on wool and is formed by exposing it to heat, moisture, and pressure.
Some of the materials used in the formulations and grades include:
Flexible graphite gaskets have superior compressive strength and recovery with very little creep. Three common types of graphite gasket sheets are reinforced (tanged, metal, metal foil, or polymer inserted), pure, and laminated with some varieties of laminated gaskets available with an adhesive backed. Flexible graphite gaskets are resistant to a wide variety of chemicals and are used in cryogenic applications and high temperature applications of 800°F up to 850°F with special grades able to withstand temperatures up to 1000°F (continuous). In oxygen free environments, gaskets are capable of sealing up to 5400°F. They provide a high performance seal in extreme conditions such as high pressure and high temperature applications.
Although flexible graphite gaskets have very low mechanical strength, they can be reinforced by being combined with fiberglass or layers of various metals such as stainless steel, nickel, Inconel, or aluminum and fabrics like fiberglass or polymer films. Much like rubber, flexible graphite gaskets have excellent compressive strength and good recovery.
Some of the grades of flexible graphite sheets include:
In addition to its high resistance to temperature, pressure, and chemicals, flexible graphite excels as a heat spreader due to its excellent thermal conductivity. It also serves as an electromagnetic interference (EMI) shield, effectively suppressing unwanted noise and electrical currents.
The outstanding properties of flexible graphite make it perfect for high-temperature applications that demand tight seals under critical conditions, such as aerospace engines, heavy truck exhaust systems, and steam power plants. It is also an excellent choice for sealing valves due to its thermal heat transfer and dissipation capabilities.
Flexible graphite is widely used across various products and applications. Different manufacturers of flexible graphite gaskets employ their own methods for identifying and classifying their products. They provide information and data to help in selecting the flexible graphite sheets that best suit specific applications.
Mixing these polymers with other substances enhances their characteristics. The formulations and grades incorporate materials such as:
These are materials that can withstand exposure to extreme temperatures.
Some of the materials used in the formulations and grades include:
Spiral wound gaskets are designed to withstand high temperatures and pressures while effectively preventing leaks. They are composed of an outer ring, an inner ring, and a sealing material.
Numerous machines are available for producing a range of gasket materials, including rubber, cork, silicone, and fiber-based substances. These machines play a crucial role in modern industry by enabling the efficient and precise manufacturing of gaskets. Gaskets are essential components in sectors like automotive, aerospace, construction, and manufacturing, where they provide sealing and prevent leaks, thereby ensuring the integrity and reliability of equipment and systems. Below, we review various brands offering machines for gasket material production, available in the United States and Canada.
The FlashCut Gasket Cutting System by Atom FlashCut has likely become popular due to its precise cutting capabilities, versatile software, and ability to handle a broad range of gasket materials. These features enable efficient and accurate production, making it a favored choice among gasket manufacturers.
Dieffenbacher's Fiberforge machine merges extrusion and lamination processes to create gasket materials with continuous lengths, customized profiles, and superior sealing properties. This innovative approach and the high-quality results it delivers have contributed to its widespread popularity.
The Zemat RCE Gasket Cutting Machine from Zemat Technology Group has gained popularity for its efficiency, high cutting speed, and precision. These features enable gasket manufacturers to streamline their production processes and meet stringent requirements effectively.
Sutherland Presses provides gasket-specific compression molding presses renowned for their precise control over temperature, pressure, and molding time. Their ability to consistently produce high-quality gaskets with superior sealing properties has made these machines highly sought after in the industry.
The Rolmacon Gasket Die Cutting Machine from Rolmacon Global Ltd is likely popular for its precise and efficient die cutting capabilities. Its ability to deliver high productivity and customization makes it well-suited for gasket manufacturers who require speed, accuracy, and flexibility.
Please be aware that specific models and features may have changed since the last update. For the most current information on the latest models and capabilities of machines used for producing gasket materials in the United States and Canada, it is recommended to consult the manufacturers or industry resources.
Most of the materials discussed earlier can be provided with or without a pressure-sensitive adhesive backing. Adding this backing reduces installation time and labor. However, it is not recommended for use in applications such as:
Several considerations should be kept in mind when choosing a gasket material appropriately for an intended application. These key considerations include:
Pressure: the pressure range that the gasket should withstand.
Temperature: the temperature range that the gasket should withstand.
Ozone and UV Exposure: how exposed will the gasket be to ozone and UV radiation.
Media: will the gasket be exposed to corrosive or abrasive fluids.
Product Standards: are there any specific product requirements within the industry.
Industry Standards: are there any industry-specific standards affecting the choice of gaskets.
Temperature considerations are usually the primary factor in selecting a gasket material, as temperature can significantly affect the material's properties, including sealing performance, compression set, and maximum stress tolerance. Both internal and external temperatures are crucial; for instance, gaskets exposed to direct sunlight may experience internal temperatures exceeding 140 degrees. Conversely, gaskets exposed to freezing temperatures can become stiff or brittle, increasing the risk of failure. Additionally, gaskets subjected to alternating cycles of cold and warmth may develop a high compression set.
UV and ozone exposure can lead to the degradation of rubber gaskets. Ozone is not only present in the atmosphere but can also be generated by electrical enclosures with high-voltage components. Both UV and ozone can break down the carbon bonds in the backbone polymers, causing the gaskets to dry, harden, scale, crack, and flake. Organic rubber gaskets, such as Buna-Nitrile, natural rubber, and synthetic isoprene, degrade more quickly under these conditions. In contrast, silicone and EPDM materials offer better resistance to UV exposure.
Joints are susceptible to deformation when pressure is applied to a system, making the selection of a gasket material that can withstand such pressure crucial. Many modern gaskets feature a PxT rating factor, which indicates the maximum pressure and temperature limits they can endure.
Industries such as automotive, aerospace, consumer electronics, and others must comply with Federal EMI product standards. Components and internal wires can emit EMI and act as antennas, necessitating control over EMI radiation. To manage this, electronic components are housed in conductive enclosures, with the lid and enclosure requiring complete contact. Thus, selecting the right conductive gasket is crucial. These gaskets not only help attenuate EMI but also provide environmental sealing.
Considering the media to which the gasket will be exposed is crucial. Generally, sealing liquids is easier than sealing gases, which should be evaluated after determining the temperature and pressure ranges. Chemical resistance is also essential, as certain chemicals can impact the gasket’s structural integrity and functional properties. It is important to assess the gasket’s chemical resistance in relation to temperature, as some fluids can become aggressive at higher temperatures. Therefore, a gasket that performs well at ambient temperatures may not maintain the same effectiveness at elevated temperatures.
Gaskets serve as mechanical seals to prevent process fluids from leaking and to keep contaminants out of sensitive areas. Each system requires a specifically suited gasket, making it essential to choose the right one for each application. It is important to balance various factors when selecting a gasket.
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