5 Must-Have Features in a rubber washer seal

13, May. 2024

 

The Ultimate Guide to Rubber Washers: Types, Benefits ...

What are Rubber Washers?

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Rubber washers are small, circular or flat-shaped components made of rubber that are designed to provide a seal or cushioning between two objects. They are commonly used in a wide range of applications, including plumbing, automotive, electronics, and construction.

Everything you need to know about Rubber Washers:

The main purpose of rubber washers is to prevent leakage or seepage of fluids or gases between the surfaces they are placed between. They act as a barrier that seals off any openings or gaps and prevents the flow of air, water, or other fluids.

Rubber washers are preferred over other materials because of their unique properties, including their ability to conform to surfaces and their resistance to chemicals and extreme temperatures. They are also highly flexible and can be easily manipulated into the desired shape or size.

Overall, rubber washers are essential components that play a critical role in ensuring the proper functioning of a wide range of machinery and equipment. Their importance in providing a leak-free and safe environment makes them a go-to choice for many industries.

Different Types of Rubber Washers

Flat Rubber Washers

These are the most common type of rubber washers typically used for applications where a tight seal is required between two flat surfaces. They come in a variety of sizes, thicknesses and materials, typically manufactured in a circular shape. The flat design of these washers allows for a larger surface area to be covered, making them suitable for applications where the load needs to be spread. They provide a reliable seal against air, water, and other fluids and are commonly used in plumbing fixtures, electrical equipment and machinery. 

O-rings are similar to circular rubber washers but with a round cross-section, designed to fit into a groove and compress between two surfaces. This allows O-Rings to provide a seal in both radial and axial directions. O-Rings are available in a range of sizes and materials, often used for hydraulic and pneumatic systems where they provide a high degree of sealing effectiveness against pressure and fluid leaks. Additionally, O-Rings can be found in many common appliances, automotive vehicles and industrial equipment. 

Bonded Rubber Washers:

These washers are made by bonding rubber to a substrate, such as metal or plastic. The bonding process is usually achieved through vulcanization, which results in an extremely strong and durable bond. Bonded rubbed washers are used in a variety of applications where a secure seal is needed between dissimilar materials including automotive fuel systems and industrial equipment. They come in a range of shapes and sizes and are typically manufactured from materials that are resistant to heat, chemicals and other harsh conditions. 

Benefits of using Rubber Washers 

Rubber washers are often preferred over plastic or metal washers for many reasons, offering a unique set of characteristics and benefits, they are used in many industries all around the globe. But what are some of the key benefits of using rubber for washer manufacturing?

Sealing Properties: Rubber washers can provide an excellent seal due to their flexibility and the way they conform to the surface they are sealing. This can make them a more suitable choice over other materials such as metal or plastic, which will not create as tight of a seal. 

Excellent Resilience: The resilience of rubber washers means they can recover their original shape even after being compressed or stretched. This means they can provide a long-lasting, reliable seal in applications where they will be subjected to repeated cycles of compression and expansion such as in valves and pumps. 

Chemical and Temperature Resistance: Rubber washers can resist a wide range of chemicals, making them suitable for use in harsh environments where exposure to corrosives is common. Depending on the rubber material used, some rubber washers can withstand extremely high or low temperatures without losing any vital sealing properties. 

Cost-Effective: Rubber washers are almost always more cost-effective than other types of washers. This makes them a popular choice for applications where a reliable seal is required but cost is a primary consideration. 

Easy to Install: Rubber washers are easy to install and require minimal tools and equipment, making them a popular choice for many applications from DIY projects to large scale industrial work. Additionally, the flexibility of rubber washers means they can often conform to slightly uneven surfaces, making them easier to work with in certain situations. 

How are Rubber Washers manufactured?

Rubber Washers are manufactured using various techniques and different machinery including CNC Digital Cutting, Hydraulic Punching and Waterjet Cutting. Among these methods, CNC digital cutting is the most common and versatile manufacturing technique for rubber washers. Here is an overview of each method:

CNC Digital Cutting 

CNC (Computer Numerical Control) digital cutting is a precise and efficient manufacturing method for rubber washers. It involves using computer controlled cutting machines equipped with specialised tools to accurately shape and cut rubber materials. CNC digital cutting offers several benefits for rubber washer production including: 

  • Cost Effectiveness - CNC Digital Cutting allows for high automation and precision, reducing material wastage and overall production costs. The CAD software allows you to embed each washer shape side by side, allowing for maximum utilisation of the rubber material, minimising waste and optimising cost effectiveness. 
  • Shorter Lead Times - The automated nature of CNC Digital Cutting enables quick setup and production, resulting in shorter lead times for manufacturing washers. This is particularly beneficial for meeting tight production schedules or urgent orders. 
  • Accuracy in Production - CNC machines are capable of achieving high levels of accuracy and repeatability in cutting rubber materials. Working to extremely high tolerances, CNC Cutting ensures consistent dimensions and shapes for the rubber washers, meeting the required specifications for a project. 

Hydraulic Punching 

Hydraulic Punching is an older and more traditional manufacturing method commonly used for smaller production runs of rubber washers. It involves using a hydraulic press equipped with specially designed cutters to create the desired dimensions and holes in rubber materials. Whilst it might be suitable for small designs or low volume production, hydraulic punching is not as precise or efficient as CNC digital cutting. 

Waterjet Cutting 

Waterjet Cutting is a specialist manufacturing process used for cutting densers, harder or thicker rubber materials that cannot be easily cut with accuracy through the standard CNC cutting process. It utilises a high-pressure jet of water mixed with abrasive particles to precisely cut through the rubber material. Waterjet cutting offers the advantage of being able to handle more challenging materials but is typically reserved for specific applications where other cutting methods are not suitable due to the increased costs of using a waterjet machine. 

In rubber washer manufacturing, CNC digital cutting stands out as a preferred technique due to its cost-effectiveness, reduced lead times and accuracy in production. However, hydraulic punching and waterjet cutting can be utilised when specific project requirements call for their unique capabilities.

Click Here to continue reading and learn about the common applications of rubber washers, how to measure them, how to choose the correct rubber material for your washers and information on where you can purchase a range of rubber washer solutions.

Gasket Material: Types, Uses, Features and Benefits

Gasket Materials

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Introduction

This article will take an in depth look at gasket materials.

You will understand more about topics such as:

  • What is a gasket?
  • Gasket materials and their functions
  • Most common gasket materials and their characteristics
  • Types of gasket materials formulations and grades
  • Gaskets with pressure-sensitive adhesive backing
  • Salient considerations for gasket material selection
  • And much more...

What are Gasket Materials?

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 the determining factors in regard to the choice of gasket materials as well as its compatibility with an application. The correct choice of material ensures that a process will function properly and efficiently without need for maintenance or repair.


The different materials are going to be discussed in the succeeding sections.

Gasket Materials and Their Functions

When choosing a gasket material or building a custom gasket, there are a wide variety of options. Some of the popular categories for gasket materials include:

Solid Materials

Solid materials are typically an alternative to sponge materials. They have the advantage of giving the gasket more durability and a longer lifespan. The lifespan of a solid gasket can be two times longer than that of a sponge material. Moreover, solid materials can withstand a higher compression force than a sponge and are thus recommended in applications that need to handle high compression forces.


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:

Silicone

Gaskets designed from solid silicone are primarily used in outdoor applications. They are applied where the physical properties of the environment are not as critical. However, resistance to extreme temperatures would still be needed. Examples include applications prone to degradation from sunlight exposure.

Fluorosilicone

Gaskets made from fluorosilicone can be used in the same conditions as silicone, although they have another advantage of chemical resistance. Resistance to chemicals like fuels and oils and resistance to extreme temperatures make fluorosilicone best suited for application in fuel delivery in automotive and aerospace industries. Fluorosilicone costs more than the silicone because of the added advantages.


Nitrile

Gaskets made from nitrile are meant for industrial applications with environmental extremes and high wear. Nitrile is a tough and durable material that also has resistance to chemicals such as oils and fuels. Other versions of nitrile can be used in food and agricultural applications.

Neoprene

Gaskets made from neoprene are more cost effective when compared to fluorosilicone and silicone. Neoprene is best suited for applications that need resistance to liquids like oil and water. Neoprene also has high resilience and elasticity, which makes it withstand elongation and tear better than silicones. It also has fatigue and abrasion resistance.

Ethylene-Propylene-Diene-Methylene (EPDM)

Gaskets made from Peroxide Cured EPDM are applied widely using rubbers with good weather, water, ozone, and UV resistance. As the Peroxide Cured EPDM is cured, heat stability makes the Peroxide Cured EPDM resistant to steam and extreme temperatures. The Peroxide Cured EPDM is less costly when compared to silicone depending on applications. However, Peroxide Cured EPDM is not best suited in applications prone to oil.


Butyl

Butyl is a synthetically made rubber that is resistant to chemicals and oils. It resists moisture and does not allow gasses to escape. Butyl is commonly applied in medical and aerospace applications.

Fluoroelastomer

The fluoroelastomer is the premium choice of solid materials as it provides synergized benefits for all solid materials. Some of the benefits include resistance to chemicals and extreme temperatures. However, it is more costly than all the other solid materials. It is mostly applied in the aerospace industry, which needs all these properties.


Fluorocarbon Gaskets

Fluorocarbon gaskets have a flat cross section and are reusable for non-critical applications. They are widely used for applications that require frequent reassembly. Fluorocarbon gaskets are an alternative to copper gaskets and used to seal conflat flanges. They are not used for high temperature applications since they lose their strength with increased temperatures.

Sponge Materials

Gaskets made from sponge materials are mostly employed when low compressional forces. Sponge materials are the choice when:

  • The housing assembly is prone to bowing or warping
  • The housing can crack at compression stops
  • Or plastic housings are used

Thus, sponge materials make these housings less affected by compressional forces. They are sometimes preferred over solid materials due to their UL flame ratings. As an example, a silicone sponge material at UL94V-0 flame rating is easier to find when compared to solid silicone.

Silicone Sponge

In applications that need compressible and soft material, silicone sponges are a preferred option for padding and gasketting. Silicone sponge has extreme temperature resistance and is therefore best suited for outdoor applications. Its closed cells are not interconnected and can prevent absorption of water and provide an excellent compression set. Out of all the silicone materials, the silicone sponge has the longest life. It can be available in extra firm, firm, medium and soft densities.


Neoprene Blend

In applications that require a compliant and soft material, neoprene blend is the best choice for gasket applications. It is a much cheaper option than solid rubber and many other sponge materials. Its applications include shock absorption, weatherstripping, thermal barrier, and for basic sealing in industries. Neoprene blend has closed cells that are not interconnected, making it impermeable to absorb water. The sponge rubber can be available in extra firm, firm, medium and soft densities.

EPDM Sponge

The EPDM sponge has the same benefits as the neoprene blend. However, its resistance to ozone is greater, making it best suited in environments where exposure to ozone is a challenge. This makes it more expensive when compared to the neoprene blend.

Foam Materials

Foam materials are similar to sponge materials in that they are recommended for use in applications that require low compressional forces. They, however, offer lower compressional forces in comparison to sponge materials. Foams are generally less expensive when compared to solid or sponge materials. They are used to provide a simple seal from the duct and primary air. They do not provide a genuine environmental seal. They are best suited where a basic seal of two materials is needed and not for critical applications outdoors.

Silicone Foams

The cellular silicone foams have extreme temperature resistance. They are employed in applications that require resilience in cushioning, sealing, vibration and insulation. They can be found in six varieties which range from ultra soft to extra firm.

Filter Foams

The filter foams are custom designed to Filter out dust. Filter foams permit air to Flow in and out of the system yet keep out dust. They are mostly used in electronic applications where dust is undesirable.


Polyurethane Foams

Polyurethane foams can be used broadly in gasketing, energy absorption, and sealing. They are less costly when compared to silicone foams. They also have a low compression set. Polyurethane foams can be available in a variety of densities and firmness within each formulation.

Polyolefin

Polyolefin is an inexpensive material in basic gasket making. It is mostly selected as a space filler to prevent two sides of a part from touching.

Foam in Place Materials (FIP)

The form in place is mostly used where a very small gasket is needed. The small gasket may be difficult to die cut and assemble. Such small gaskets are flimsy to manage and elongate time and effort in assembling. In such cases, form in place gaskets are selected to reduce assembly cost. The gasket is dispensed into the unit and cured. FIP materials are typically used in electronic devices due to their size.

Silicone

Silicone sealants and adhesives cure upon exposure to ambient humidity. They have good sealing properties and set well in the majority of ozone, weather, and compression conditions with electrical insulation properties. Silicone sealant can be applied on overhead, vertical, and horizontal surfaces depending on the viscosities.

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When uncured, silicone is capable of adhering to small objects as it cures. When applied in FIP, silicone has high temperature performance but low temperature flexibility. It has a wide range of applications due to it being readily available.

UV Materials

These get used when lead time and production are a priority. UV Materials do not need much curing time after dispensing as silicone does. This makes the turn around faster. UV materials are preferred where high volume and high throughput production are prioritized.


EMI Form In Place Materials

EMI materials are the most popular type of FIP gaskets used in various applications. They meet the requirements of the EMI applications and are best suited when precise and small gaskets are needed. EMI materials can shield between two gasket sides and can be 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

Silicone extrusions merge two types of gaskets i.e. EMI shielding and environmental seal into one product. It has a thin shield that is electrically conductive and is co-extruded on a silicone rubber base. They are a good option when there is a need to put a gasket into a grove. In cases where the grove is too small for extrusion, then FIP dispensing is more preferred. Extrusion yields a lower compression force because it is softer when compared to FFIP dispensing.

Silicone

EMI shielding silicone products are conductive as they have a conductive filler which can be nickel, copper, or aluminum. It is very flexible and can fit many designs and sizes, although it is not best suited for harsh environments such as sunlight or caustic chemicals. Such harsh environments can impair the shielding and sealing. Therefore, it is mostly used as connector gaskets or on print circuit boards or electronics.


Fluorosilicone
  • To be conductive, the fluorosilicone uses a fluorinated silicone elastomer base which prevents degradation from harsh environmental conditions. A conductive filler like nickel, aluminum, or copper also helps to enhance conductivity. For additional strength, fluorosilicone may have cloth inserts for tear resistance.
  • Fluorosilicone gaskets are resistant to hydrocarbons from harsh environmental conditions and can be applied in PCBs, just like silicone. It is a chemically resistant material that can be used in gaskets exposed to acetones or detergents. It is thus more costly than silicone.
Nickel Taffeta Foam
  • This fabric is mostly used in applications that need low compressional forces. Its applications include electronics that are stacked in layers in servers and cabinets.

Microwave Absorbing Materials

  • These are dense foam and rubber based absorbers which are resistant to ozone, UV and high temperatures. They are thin and magnetically loaded. They also have a high loss at microwave frequencies but maintain elastomeric binders characteristics. They are designed to lower the Q-factor in cavities as well as attenuating cavity oscillations. In as much as they are not really EMI materials, they are used in EMI applications to absorb frequencies from electronic components emission instead of bouncing them back as EMI materials would.

Thermal Interface Materials

These materials are used in dissipating heat in a component. The selection of the thermal interface material depends on the amount of power output over a time frame. Silicone is widely used for this type of gasket due to its high temperature capabilities. The right conductivity of the material needs to be chosen in order to dissipate the required heat. The more the heat dissipates, the more costly the material is. As with fluorosilicone, silicone materials may have cloth inserts to enhance their tear resistance.

Gap Fillers Silicone
  • These are commonly used for customized gasket production for PCBs or chips applications. They are specifically used where there is a gap between housings mated together and needs to be filled. The gasket is intended to transfer heat to housing made of aluminum which then dissipates heat.
Gap Fillers Acrylic
  • They have the same benefits as silicone gap fillers though they have additional properties to prevent outgassing. The acrylic pads have no materials associated with silicone products such as oil bleeding or siloxane VOC. These materials can cause device failure. The outgassing of silicone can be a source of contamination, especially in electronics hard drives. Therefore, acrylic gap fillers are more suitable for such applications as they are not prone to outgassing.

Silicone Pad Materials

  • The Sil-pad materials are used where a silicone gap filler is preferred but the gap will be very thin. The use of the pads allows it to have the same material benefits while fitting into much smaller gaps.

Thermal Tape
  • These are best suited in creating a structural bond with the custom gasket. Thermal tapes are typically used when two sides of a part need to be bonded together while dissipating heat. They are mostly used in bonding heatsinks to circuit boards.
Thermal Paste
  • Thermal pastes have a wide range of thickness options, unlike pre-formed gap filling materials. They do not need die cut shapes or specific pad thicknesses for different applications. In cases where low compressional forces are needed, thermal pastes can replace gap fillers. They don't pose any stress on components when assembling. Their drawback is that they are messy. They are thus cost effectively used in high volume applications where precision is not a priority.

Leading Manufacturers and Suppliers

    Most Common Gasket Materials and their Characteristics

    From the different gasket materials available,some are most commonly used. This is because they pose unique characteristics favorable for respective applications. These include:

    Cork Gasket Materials

    These are very lightweight and stable materials which can resist penetration by water. They have good compressibility, no lateral flow, and high resistance to oil. The cork is resistant to wear and is not affected by high temperatures.


    Cork & Rubber Gasket Materials

    These combine granulated cork and synthetically made rubber polymers. They have a high resilience and flexibility of rubber and compressibility of cork. Additionally, the rubber can provide chemical compatibility, sealant properties, and resist weather conditions and acids. A wide range of rubber gasket materials can be chosen based on chemical resistance requirements.

    Silicone Gasket Materials

    These are available as sponge, foam, or solid. Regardless of the state, their characteristics include stability at high temperatures, general inertness, and resilience. Some benefits of silicone include:

    • Waterproof - water exposure over time does not degrade it
    • Flexibility - High or low temperatures do not crack or freeze it
    • Shrink proof - It doesn’t shrink over time

    However, the most common drawback of silicone is that it is not best suited for numerous hydrocarbons and steam.

    Natural Rubber Gasket Materials

    Natural rubber has excellent recovery properties. It also has great resistance to most inorganic salts, alkalis, and mild acids. It is, however, not suitable for oils and solvents or 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.


    Urethane Gasket Materials

    Urethanes have excellent aging and abrasion characteristics, although they are not best suited for extreme temperatures. Some of the characteristics of urethanes include:

    • Waterproof - They can also be used in volatile weather conditions
    • Elasticity - They can stay flexible regardless of temperature changes
    • Flexible - They can conform to the application shape

    Neoprene Gasket Materials

    This has excellent resistance to UV and ozone, good tear strength, and strong resilience though it can be damaged easily by petroleum based fuels. Some of the characteristics include:

    • Capability to Foam a permanent seal that is not prone to being broken or reestablished.
    • Has good flexibility and chemical stability over a wide range of temperatures
    • Has waterproof properties and is corrosion resistant

    Types of Gasket Materials Formulations and Grades

    As previously discussed, there are different gasket materials available in the industry. Each of them can be used to meet certain criteria. For the different gasket materials, the formulations and grades can be made from different materials.

    Rubber

    Rubber’s formulations and grades can be used in a wide range of applications depending on operating and environmental conditions.


    Some of the materials used in the formulations and grades include:

    • Peroxide Cure EPDM
    • Conductive Silicone
    • EPDM Nylon Inserted
    • Butyl
    • FDA Approved (Food Grade)
    • Natural (Gum) Rubber
    • Cloth-Inserted (CI)
    • Fluorosilicone
    • Diaphragm
    • Neoprene (Chloroprene)
    • EPDM
    • Latex
    • SBR (Red Rubber)
    • Thermoplastic Rubber (TPR)
    • Neoprene Nylon Inserted
    • Urethane
    • Nitrile (Buna-N)
    • Polyurethane
    • Silicone
    • Santoprene

    Rubber Moulding Compounds

    These are used in molding operations such as transfer molding, compression molding, and injection molding. They create gaskets in different sizes and shapes.


    Some of the materials used in the formulations and grades include:

    • Hydrogenated Acrylonitrile (HNBR)
    • Silicone (VMQ)
    • Styrene-Butadiene (SBR)
    • Polyurethane (AU, EU)
    • Ethylene-Propylene (EPDM, EP, EPT)
    • Neoprene, Chloroprene (CR)
    • Nitrile, Buna-N (NBR)
    • Fluorosilicone (FVMQ, FMQ)
    • Polyacrylate Acrylic (ACM)
    • Epichlorohydrin (EPI)
    • Natural Rubber, Polyisoprene (IR, NR)

    Closed-Cell Sponge Rubber

    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:

    • Silicone Sponge
    • EPDM Sponge
    • Neoprene/EPDM/SBR Sponge Blend
    • Epichlorohydrin (ECH) Sponge
    • Neoprene Sponge
    • PVC-Nitrile Sponge

    Open-Cell Sponge Rubber

    This has interconnected cells that permit liquids, gasses, and other fluids to pass through. Open-cell sponge rubbers are available in five density levels that range from soft to extra firm.


    Some of the materials used in the formulations and grades include:

    • Natural Open Cell Sponge
    • SBR Open Cell Sponge
    • Neoprene Open Cell Sponge

    Compressed Non-Asbestos

    These consist of non-asbestos fibers, which can be aramid or fiberglass, merged with rubber. The formulation yields a better pressure and temperature performance.


    Some of the materials used in the formulations and grades include:

    • Garlock Blue-Gard
    • Frenzelit Novapress

    Cork

    Cork has high flexibility and compressibility. A combination of cork and rubber, for example neoprene or nitrile, yields a gasket resistant to solvents, oils, and fuels.


    Some of the materials used in the formulations and grades include:

    • Cork & Neoprene Blend
    • Cork & Viton Blend
    • Composition Cork
    • Cork & EPDM Blend
    • Cork & Silicone Blend
    • Cork & Synthetic Rubber
    • Cork & Nitrile Blend

    Electrical Insulation

    These materials do not have electrical conductivity and are used in electrical applications.


    Some of the materials used in the formulations and grades include:

    • Fish Paper
    • Lexan Polycarbonate
    • Hitex
    • Vulcanized Fiber

    RFI/EMI Shielding

    These are materials used in protecting electronic and electrical devices from radio frequency and electromagnetic interference.


    Some of the materials used in the formulations and grades include:

    • Chomerics Metalastic
    • Chomerics Soft-Shield
    • Conductive Silicone Rubber

    Fiber

    Fiber consists of a variety of fiber-based materials which include insulating fiber, cellulose fiber, synthetic fiber and vegetable fiber.


    Some of the materials used in the formulations and grades include:

    • Compressed Fiber Sheet
    • Cellulose/Synthetic Rubber Beater Ad
    • Cellulose Fiber Board
    • Vegetable Fiber (Detroiter)
    • Velbuna
    • Cellulose/Nitrile Rubber Beater Ad
    • Cellulose Fiber Paper
    • Non-Asbestos NBR Aramid Fiber

    Foam

    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:

    • Microcellular Urethane Foam
    • Closed Cell EVA foam
    • Cross-linked Polyethylene Foam
    • Polyurethane Foam
    • Filter Foam
    • Silicone Foam
    • Convoluted Egg-Crate Foam
    • Vinyl Foam
    • Multi-Planar EMI Foam
    • Polyethylene Foam
    • Neoprene Foam
    • Polystyrene Foam
    • Polyester Foam
    • Sound Foam
    • Polyether Foam

    Felt

    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:

    • Felt Wicking
    • Polyester Felt
    • Decorative Pure Felt
    • SAE Grades
    • Needled Felt
    • Wool Felt
    • Woven Wool Felt
    • Sheet Felt
    • Felt Stripping
    • Acoustic Grade

    Flexible Graphite

    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:

    1. Industrial - Industrial grade graphite sheets are the most commonly used with a carbon content of 98%.
    2. Nuclear - Nuclear graphite is a high purity graphite foil with tighter control on chemical impurities. The various nuclear grade foils are typically used where detailed chemical analysis reports are needed or in sensitive applications where these impurities could have adverse effects.
    3. Oxidation Resistant - Oxidation resistant graphite is made from ultra high purity graphite foil with special additives to prevent oxidation. The types of applications that require the highest degree of temperature resistance use oxidation resistant foils.

    Aside from its high temperature, pressure, and chemical resistance, flexible graphite acts as a heat spreader with excellent thermal conductivity. Additionally, it performs as an electromagnetic interference (EMI) shield to suppress unwanted noise and electrical currents.

    The exceptional quality of flexible graphite makes it ideal for several types of high temperature applications that require a tight seal in critical conditions such as aerospace engines, heavy truck exhausts, and steam power plants. It is ideal as a sealing material for valves in addition to its thermal heat transfer or dissipation properties.

    Flexible graphite is a material that is commonly used in a wide array of products and applications. Each flexible graphite gasket manufacturer has their own unique methods for identifying and classifying their products and have information and data that assist in finding the flexible graphite sheets that can exactly fit an application.

    Plastics

    These polymers have their characteristics enhanced by mixing them with other substances. Some of the materials used in the formulations and grades include:

    • PTFE
    • Polycarbonate
    • Acetal
    • ABS
    • Acetate
    • Nylon
    • Ultra High Molecular Weight (UHMW)
    • High Density Polypropylene (HDPE)
    • Low Density Polyethylene (LDPE)
    • PVC
    • Polypropylene
    • High Impact Polystyrene
    • Phenolic
    • Vinyl (Rigid & Flexible)
    • PETG

    High Temperature Materials

    These are materials that can withstand exposure to extreme temperatures.


    Some of the materials used in the formulations and grades include:

    • Silicone Coated Fiberglass
    • Flexible Graphite
    • Fluorosilicone
    • Compressed Non-Asbestos
    • Silicone Sponge and Foam
    • Conductive Silicone

    Spiral Wound Gaskets

    Spiral wound gaskets are capable of withstanding high temperatures and pressures as well as prevent leaks. They consist of an outer ring, inner ring, and sealing material.

    • Outer Ring: The outer ring is made of carbon steel and is referred to as the centering ring or guide ring. It centers the gasket when it is inserted.
    • Inner Ring: The inner ring prevents windings from buckling and helps avoid problems.
    • Sealing Material: The sealing material prevents leaks and is placed around the windings and filler material. Most spiral gaskets use flexible graphite that is rated for high temperatures or polytetrafluoroethylene (PTFE), which is not rated for high temperature applications.

    Leading Manufacturers of Gasket Material Producing Machines

    There are many machines available to produce various materials suitable as gasket materials, such as rubber, cork, silicone, and fiber-based materials. These machines are important in today's society because they enable the efficient and precise manufacturing of gaskets, which are critical components used in industries such as automotive, aerospace, construction, and manufacturing to provide sealing and prevent leakage, ensuring the integrity and reliability of equipment and systems. Below, we discuss various brands that offer machines used for producing gasket materials, available in the United States and Canada.

    Atom FlashCut - FlashCut Gasket Cutting System:

    The FlashCut Gasket Cutting System from Atom FlashCut has likely gained popularity due to its precise cutting capabilities, versatile software, and the ability to handle a wide range of gasket materials. These features allow for efficient and accurate production, making it a preferred choice for gasket manufacturers.

    Dieffenbacher - Fiberforge:

    Dieffenbacher's Fiberforge machine combines extrusion and lamination processes to produce gasket materials with continuous lengths, customized profiles, and excellent sealing properties. This innovative approach and the resulting high-quality output have contributed to its popularity.

    Zemat Technology Group - Zemat RCE Gasket Cutting Machine:

    The Zemat RCE Gasket Cutting Machine by Zemat Technology Group has become popular due to its efficiency, high cutting speed, and accuracy, allowing gasket manufacturers to optimize their production processes and meet demanding requirements.

    Sutherland Presses - Gasket Compression Molding Presses:

    Sutherland Presses offers gasket-specific compression molding presses, which have gained popularity for their precise control over temperature, pressure, and molding time. The ability to consistently produce high-quality gaskets with excellent sealing properties has made these machines sought after in the industry.

    Rolmacon Global Ltd - Rolmacon Gasket Die Cutting Machine:

    The Rolmacon Gasket Die Cutting Machine from Rolmacon Global Ltd is likely popular due to its accurate and efficient die cutting capabilities. By enabling high productivity and customization, this machine can meet the demands of gasket manufacturers seeking speed, accuracy, and flexibility.

    Please note that specific models and features may have evolved since this last update. It is advisable to consult the respective manufacturers or industry resources for the most up-to-date information on the latest models and capabilities of machines used for producing gasket materials in the United States and Canada.

    Gaskets with Pressure Sensitive Adhesive Backing

    Most of the materials discussed previously can be available with or without the pressure sensitive adhesive backing. Adding a pressure sensitive adhesive backing minimizes time and labor requirements when installing gaskets. It is, however, not recommended in applications such as:

    • When EMI shielding gaskets are used. The effectiveness of the shielding material can be reduced by the adhesive.
    • When solvent resistance is a priority. The adhesive is prone to damage and degradation from solvents.
    • When the flat surface area is minimal. Without sufficient surface area, the adhesive cannot form a good bond.
    • When the gasket is exposed to high stress. The adhesive is prone to losing its integrity over time.

    Salient Considerations for Gasket Material Selection

    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

    Temperature considerations are typically the starting point when choosing a gasket material. This is because of its ability to change the material’s characteristics, including sealing properties, compression set, and maximum stress it can withstand. Internal and external temperatures are important to consider because gaskets exposed to direct sunlight can experience internal temperatures that can go beyond 140 degrees. On the contrary, if the gasket is exposed to freezing temperatures, it can become stiff or brittle and make it more prone to failing. If gaskets experience back and forth cycling from cold to warm alternately, it can end up having a high compression set.

    Ozone and UV Considerations

    UV and ozone exposure can cause rubber gaskets to degrade. The atmosphere is not the only source of ozone. Electrical enclosures that have electrical components at high voltage can also be a source of ozone. UV and ozone can have the backbone polymers’ carbon bonds broken down, resulting in drying, hardening, scaling, cracking, and flaking. Organic rubber gaskets such as Buna-Nitrile, natural rubber, and synthetic isoprene break down quicker. Silicone and EPDM are the two materials that can better resist UV.

    Pressure Considerations

    Joints are prone to deformation when pressure is exerted onto a system. Thus, the choice of a gasket material that can withstand such pressure is critical. Some contemporary gaskets now have a PxT rating factor that advises on the pressure and temperature maximum limits.

    Electromagnetic Interference (EMI) Considerations

    Industries such as automotive, aerospace, consumer, and electronics industries are obliged to adhere to product standards of the Federal EMI. Components and internal wires can emit EMI and can function as emitting antennas. In controlling EMI radiation, electronic components are encased in conductive enclosures. The lid and the enclosure should have complete contact. Therefore, it is critical to choose an appropriate conductive gasket. The gaskets can be a source of EMI attenuation and environmental sealing.

    Media Considerations

    The media which the gasket will be exposed to is an important consideration. Generally, a liquid is much easier to seal compared to a gas. This can be considered once the temperature and pressure ranges have been decided on. There are chemicals that can affect the structural integrity and functional properties of the material. Thus, the gasket’s chemical resistance is vital. This has to be considered in relation to the temperature effect on the chemical resistance. Some fluids are aggressive when exposed to certain temperatures. Thus, fluids sealed at an ambient temperature may not yield the same performance at higher temperatures.

    Conclusion

    Gaskets are used as mechanical seals to prevent process fluids from escaping or contaminants from entering the delicate areas. Each given system has its best suited gasket, and it is critical to make the right gasket choice for each. A balance between the different considerations of gasket selection should be struck.

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