Choosing the right rubber for custom sealing rings and gaskets and gaskets can make or break your application. There are many types of rubber materials used in seals, each with unique physical and chemical properties. It is very important to select the right rubber material according to the requirements of different application environments, such as temperature, chemical media, pressure, etc., which directly affects the functionality, durability and stability of the seal. This article is to help readers understand the importance of selecting the appropriate rubber material for custom sealing rings and gaskets based on various factors.
1. Silicone Rubber (SR)
Silicone rubber is a versatile elastomer known for its exceptional performance across a wide temperature range. It remains highly flexible and functional in extreme temperatures, from -60°C to +250°C (-76°F to +482°F). This broad temperature tolerance makes it ideal for use in applications that experience both intense heat and cold. Additionally, silicone rubber is non-toxic, odorless, and resistant to UV and ozone exposure, ensuring its durability even in harsh outdoor environments. Its biocompatibility also makes it a popular choice for medical and food-grade applications.
Pros:
- Excellent resistance to extreme temperatures.
- Biocompatibility and non-toxicity make it suitable for medical and food applications.
- Good electrical insulation properties.
- Superior resistance to UV and ozone degradation.
Cons:
- Poor mechanical strength compared to other rubbers.
- Limited resistance to oils, fuels, and many solvents.
- Can suffer from lower tear and abrasion resistance in dynamic applications.
Applications
Silicone rubber is widely used across various industries due to its unique properties. Here’s a breakdown of its applications in different industries:
- Automotive: Silicone rubber is commonly used for sealing rings and gaskets in engines and other high-temperature components. Its ability to withstand extreme heat makes it essential for automotive applications, ensuring reliable seals even in demanding environments.
- Medical: In the medical industry, silicone rubber is used for gaskets in sterilizable devices. Its biocompatibility and resistance to temperature extremes make it an ideal material for medical equipment that must meet strict hygiene and safety standards.
- Household Appliances: Silicone rubber is very commonly seen in the kitchen like coffee makers and ovens. Its heat resistance ensures that silicone seals and components can perform consistently in appliances exposed to high temperatures.
- Electronics: In electronics, silicone rubber is used for waterproof seals in devices such as smartphones. Its durability and ability to resist moisture and environmental factors ensure long-lasting protection for sensitive electronic components.
Alternatives
Due to the limitations of silicone rubber materials, if better oil resistance and high temperature resistance are hard requirements, then fluorine silicone rubber (FKM) is a good alternative; if low cost and water resistance are considered, EPDM is the best alternative
2. Nitrile Rubber (NBR)
Nitrile Rubber (NBR) is known for its excellent chemical resistance against oil and liquid fuel, making it ideal for dynamic applications that involve high mechanical stress. Its outstanding oil resistance is one of the best among common elastomers, allowing it to perform reliably in harsh environments while maintaining long-term durability and mechanical performance.
Pros:
- Superior resistance to oils, fuels, and many chemicals.
- High wear resistance and tear strength.
- Good low-temperature flexibility (down to -40°C / -40°F).
- Cost-effective and widely available.
Cons:
- Poor ozone and UV resistance—degrades when exposed to sunlight or oxygen.
- Not suitable for use in high-temperature environments (max temperature around 120°C / 248°F).
- Limited resistance to strong acids and solvents.
Applications
Nitrile rubber excels in environments where frequent exposure to petroleum-based fluids, oils, and fuels is common. It is commonly found in the automotive industry, such as in fuel system seals and engine oil seals. It’s also a key material in hydraulic equipment, oil seals, sealing rings and gaskets used in industrial machinery.
Alternatives
While nitrile rubber (NBR) performs well in applications involving petroleum-based fluids, it has certain limitations that may require alternative materials. For high-temperature environments exceeding 100°C, HNBR or FKM offer better thermal stability. In cases of prolonged outdoor use or ozone exposure, EPDM is a more suitable option due to its superior weather and ozone resistance. When dealing with strong acids, bases, or ketones, FFKM (perfluoroether rubber) should be used, as it provides exceptional chemical resistance in aggressive environments.
3. EPDM Rubber (Ethylene Propylene Diene Monomer)
EPDM rubber is known for its outstanding weatherability, including resistance to ozone, UV radiation, extreme temperatures and outdoor conditions. EPDM is also highly resistant to steam, hot water, and glycols, making it an excellent choice for plumbing seals or heating and cooling systems. There it is commonly used in both static and dynamic sealing applications due to its good compression set resistance.
Pros:
- Excellent outdoor durability (ozone, UV, and weather resistance).
- High temperature tolerance (up to 150°C / 302°F).
- Great resistance to water, steam, and polar chemicals.
- Flexible at low temperatures (down to -50°C / -58°F).
Cons:
- Poor resistance to oils, fuels, and hydrocarbon solvents.
- Moderate mechanical strength—less durable than NBR or FKM in high-wear environments.
- Can be prone to swelling when exposed to certain hydrocarbons.
Applications
EPDM is widely used in scenarios: water, steam, hot water, ozone exposure, outdoor environment and applications that require high durability, including automotive seals, weatherproofing, roofing, and plumbing. In the automotive industry, it’s commonly found in radiator seals, window weatherstripping, and door gaskets. Its excellent weather resistance also makes it ideal for water-resistant seals in outdoor equipment and machinery, a preferred choice for applications that demand long-lasting performance.
Alternatives
However, EPDM is not suitable for applications involving contact with oil-based substances such as gasoline, lubricants, or diesel. For better oil and weather resistance, fluorine rubber (FKM) is a more appropriate choice. If high temperature resistance and flexibility are the priority, silicone rubber (SR) is the best alternative.
Related reading: What Is EPDM Seal and Gasket?
4. Isoprene Rubber (IR)
Isoprene rubber, a synthetic alternative of natural rubber, closely mimics the properties of natural rubber due to its similar molecular structure. It offers excellent elasticity, resilience, and rebound, making it ideal for applications that require frequent deformation and recovery. Its strong abrasion resistance also makes it perfect for seals exposed to regular movement or compression.
Pros:
- Excellent elasticity and flexibility, similar to natural rubber.
- High rebound and abrasion resistance, making it suitable for custom dynamic sealing applications.
- Comparable performance to natural rubber, with more consistency in quality and fewer impurities.
Cons:
- Weather resistance is relatively low, especially when exposed to ozone, UV light, or extreme outdoor conditions.
- Moderate heat resistance, typically suitable for applications up to 80-100°C (176–212°F).
- Chemical resistance is not as high as synthetic rubbers like nitrile or fluorocarbon.
Applications
Isoprene rubber is widely used in applications that require the resilience and elasticity of natural rubber but with more controlled consistency. It is commonly used for automotive seals, o-rings, gaskets, and vibration-damping components in machinery. It is also used in medical and consumer goods applications, where its high elasticity and low impurities are desirable.
5. Styrene Butadiene Rubber (SBR)
Styrene Butadiene Rubber (SBR) is one of the most widely used synthetic rubbers in the world, primarily due to its cost-effectiveness and versatile properties. SBR is produced by copolymerizing styrene and butadiene, combining the strengths of both materials. SBR offers good abrasion resistance, tensile strength, and aging stability, which makes it suitable for a variety of custom sealing gaskets and rings in dynamic and static environments.
Pros:
- Good abrasion resistance and flexibility, making it ideal for sealing applications subject to wear and tear.
- Aging resistance, which allows it to maintain functionality for a longer period.
- Cost-effective, which makes it a popular choice for general-purpose seals and gaskets.
- Resistant to water and mild chemicals, making it suitable for use in environments where exposure to these elements is common.
Cons:
- Poor ozone and UV resistance, which means it can degrade over time when exposed to sunlight or atmospheric ozone.
- Limited oil resistance compared to materials like nitrile or FKM, making it unsuitable for sealing applications involving petroleum products.
- Moderate heat resistance, typically up to 70-100°C (158–212°F), which limits its use in high-temperature environments.
Applications
SBR is widely used in automotive tires, gaskets, and sealing rings in industrial machinery. It is also used in vibration damping components, floor mats, and insulating materials. For sealing rings and gaskets, SBR is most commonly found in low to medium-temperature environments, where the material is not exposed to harsh chemicals or ozone.
6. Butadiene Rubber (BR)
Butadiene rubber (BR) is a synthetic rubber that is primarily known for its high elasticity and excellent low-temperature flexibility. It is made from the polymerization of butadiene, which results in a material with outstanding rebound properties. Butadiene rubber is highly resistant to abrasion and has a low compression set, making it ideal for sealing applications that involve dynamic motion or high-pressure environments.
Pros:
- Excellent low-temperature flexibility, making it ideal for applications exposed to cold environments (e.g., cryogenic seals).
- High elasticity and rebound properties, which enable it to return to its original shape after deformation.
- Good wear resistance, ideal for seals in high-abrasion environments.
Cons:
- Poor weather resistance—butadiene rubber is susceptible to ozone, UV degradation, and outdoor exposure unless specifically treated.
- Limited oil and chemical resistance—not suitable for environments with exposure to oils, fuels, or harsh solvents.
- Moderate heat resistance, typically suitable for temperatures up to 90-100°C (194–212°F).
Applications
Butadiene rubber is commonly used in automotive tires, shock absorbers, and vibration damping seals due to its excellent elasticity and rebound characteristics. In sealing applications, it is suitable for low-temperature environments and is often found in gaskets and O-rings where high flexibility and wear resistance are required.
More reading: Understanding the Rubber Extrusion Process
7. Neoprene Rubber (CR)
Neoprene rubber, also known as chloroprene rubber, is a synthetic elastomer valued for its balanced set of properties, especially oil and odor resistance. It offers moderate oil resistance, good abrasion resistance, strong weather resistance, and built-in flame retardancy. Neoprene performs well in both static and dynamic sealing applications, and its moderate chemical resistance makes it a reliable option for environments with occasional exposure to oils, solvents, or outdoor conditions.
Pros:
- Moderate oil and weather resistance.
- Good flame resistance—self-extinguishes.
- Balanced properties make it suitable for a wide range of applications.
- Good vibration and noise damping.
Cons:
- Limited low-temperature flexibility.
- Not as resistant to oils and fuels as nitrile or FKM.
- Can degrade under prolonged exposure to ozone, UV, and extreme heat.
Applications
Thanks to these qualities, neoprene is widely used in automotive seals, gaskets, O-rings, vibration mounts, and electrical insulation. It’s especially suited for weather seals and outdoor uses where protection from moisture, sunlight, and chemicals is required, making it a versatile and cost-effective choice for general-purpose sealing and damping needs.
8. Polyurethane Rubber (PU)
Polyurethane rubber is known for its outstanding abrasion resistance, tear resistance, and high mechanical strength. This elastomer is used in applications requiring excellent durability and resistance to high wear and stress, such as hydraulic seals, piston rings, and heavy-duty machinery seals. Polyurethane also has good oil resistance and chemical resistance but is limited in its temperature tolerance—typically, polyurethane can handle up to 90°C (194°F), and higher temperatures can cause it to soften or degrade.
Pros:
- Unmatched abrasion resistance and tear strength.
- High resilience—ideal for dynamic sealing applications.
- Excellent for high-stress environments.
- Good resistance to oils, solvents, and chemicals.
Cons:
- Poor low-temperature flexibility—becomes rigid below -20°C (-4°F).
- Limited heat resistance, typically up to 90°C (194°F), though specialized grades can handle higher temperatures.
- Higher cost compared to nitrile and other standard rubbers.
Applications
Polyurethane is used in dynamic seals where abrasion resistance is paramount, such as hydraulic seals, piston seals, rollers, and machinery seals in industrial equipment. It is also used in automotive applications such as suspension components and shock absorbers.
Recommended reading: Key Molding Processes of Silicone Rubber Sealing Rings
9. Fluorine Rubber (FKM)
Fluorine rubber (FKM), often referred to by brand names like Viton®, is a high-performance elastomer known for its exceptional resistance to a wide range of chemicals, high temperatures, and harsh environments. FKM is widely used in applications where other rubbers would fail due to exposure to aggressive fluids, extreme heat, or UV radiation. Its unique structure, consisting of fluorine atoms bonded to the carbon backbone, provides unparalleled chemical stability and high-temperature resistance. FKM is highly effective in sealing applications where performance and longevity are critical.
Pros:
- Superior chemical resistance to oils, fuels, solvents, and acids, which makes it ideal for industries like aerospace, automotive, and chemical processing.
- High-temperature stability, typically resisting temperatures up to 250°C (482°F), with some specialized compounds capable of withstanding even higher temperatures.
- Excellent resistance to UV light and ozone, which allows FKM seals to perform well in outdoor environments exposed to sunlight and atmospheric conditions.
- Long service life in demanding conditions, reducing the frequency of maintenance and replacements.
Cons:
- Poor low-temperature flexibility—FKM can become brittle at temperatures below -20°C (-4°F), which limits its use in cold environments.
- Higher cost compared to other elastomers, which may make it less suitable for cost-sensitive applications.
- Limited resistance to certain acids and chemicals, although it generally performs better than most elastomers in harsh chemical environments.
Applications
FKM is widely used in high-performance sealing applications in sectors where exposure to heat, chemicals, or fuels is common. It is used in aerospace fuel seals, automotive fuel system O-rings, hydraulic seals in heavy machinery, and chemical processing equipment. Its ability to handle extreme temperatures and aggressive fluids makes it an essential material for industrial custom gaskets and automotive engine seals.
10. Fluorine Silicone Rubber (FVMQ)
Fluorine silicone rubber (FVMQ) is a hybrid material that combines the best properties of silicone and fluorine rubber. This elastomer combines the temperature resistance and flexibility of silicone with the chemical resistance of fluorine rubber, resulting in a high-performance material capable of withstanding extreme environments. Fluorine silicone rubber retains many of the desirable properties of standard silicone, such as low toxicity, good electrical insulation, and stability over a wide temperature range, while adding the oil and chemical resistance typically associated with fluorocarbon rubbers.
Pros:
- Outstanding high and low-temperature resistance, with service temperatures ranging from -60°C (-76°F) to +250°C (+482°F), making it suitable for a wide array of applications.
- Excellent chemical and oil resistance, particularly to fuels, oils, and solvents, similar to pure fluorocarbon rubbers.
- Superior flexibility at both high and low temperatures, ensuring excellent sealing performance in fluctuating temperature environments.
- Good weathering and UV resistance, allowing it to perform well in outdoor conditions.
Cons:
- Limited low-temperature flexibility compared to pure silicone, as it can become stiff in extremely cold environments.
- Costlier than standard silicone, making it less economically viable for less demanding applications.
- Moderate mechanical strength—while better than silicone, fluorine silicone rubber may still not match the mechanical properties of other rubbers like nitrile or polyurethane under high mechanical load conditions.
Applications
Fluorine silicone rubber is commonly used in automotive, aerospace, and chemical processing applications where seals are exposed to extreme temperatures and aggressive fluids. It is used for fuel system seals in aviation, high-temperature seals in automotive engines, and chemical-resistant custom gaskets in industrial equipment. It is also employed in medical applications that require both chemical resistance and temperature stability, such as seals for sterilization equipment.
Fluorine Rubber (FKM) vs. Fluorine Silicone Rubber (FVMQ)
| Property | Fluorine Rubber (FKM) | Fluorine Silicone Rubber (FVMQ) |
| Temperature Range | -20°C (-4°F) to +250°C (+482°F) (some grades up to 300°C (+572°F)) | -60°C (-76°F) to +250°C (+482°F) |
| Chemical Resistance | Excellent resistance to oils, fuels, solvents, and acids | Excellent resistance to oils, fuels, solvents, and chemicals |
| UV/Ozone Resistance | Excellent | Good (better than standard silicone) |
| Low-Temperature Flexibility | Poor (can become brittle below -20°C / -4°F) | Moderate (flexibility reduced at low temperatures) |
| Heat Resistance | Excellent (up to 250°C / 482°F) | Excellent (up to 250°C / 482°F) |
| Mechanical Strength | High (tough and durable under mechanical stress) | Moderate (better than silicone, but not as strong as FKM) |
| Flexibility | Moderate (becomes stiff in cold environments) | Excellent (good flexibility across a broad temperature range) |
| Cost | Higher cost compared to most elastomers | Higher cost compared to standard silicone |
| Applications | Automotive fuel seals, aerospace, hydraulic systems, gaskets | Fuel system seals in aviation, high-temp automotive seals, chemical-resistant gaskets |
| Primary Benefit | High-performance material for extreme temperatures and chemicals | Combines high-temperature resistance and chemical resistance with flexibility of silicone |
More information about rubber materials: Rubber Raw Material Introduction
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In Summary
Selecting the right rubber material for sealing rings and gaskets involves considering various factors such as temperature resistance, chemical compatibility, mechanical strength, abrasion resistance, and cost. Each material has its strengths and weaknesses. For extreme temperatures, silicone or FKM might be necessary. For oil and fuel exposure, nitrile rubber is the preferred choice, while EPDM excels in weather and steam resistance. Polyurethane is ideal for high-wear, high-stress environments, and neoprene offers a balanced approach to sealing in diverse applications.
