Compression Set

Compression set occurs when a gasket fails to return to its original thickness after being subjected to prolonged compressive stresses at a given temperature and deflection. The causes include excessive loads or overtightening, but exposure to high heat and chemicals can also contribute to this form of failure.

To prevent compression set, select a gasket material (such as silicone rubber) with good compression set properties. Silicone has a molecular structure that rebounds better than most elastomers, and it maintains its elasticity over time. It’s also important to determine if the gasket design and material are right for the application, and if the installation procedure is correct.

Overfilling the Gland

A gland is a groove or cavity that houses, supports, and compresses a custom gasket. To provide proper sealing, the gasket needs enough space to compress and deform under pressure. If the gland is overfilled, however, the seal will extend beyond the lower pressure side and begin to tear. This can cause one side of the gasket to appear frayed, worn, or “nibbled”.

To avoid overfilling the gland, aim for 80% to 90% gland fill. If redesigning the gland isn’t possible, reducing the gasket’s width is often the simplest adjustment. Many high consistency rubber (HCR) materials are available in a range of standard thicknesses, and liquid silicone rubber (LSR) supports molded gaskets for specific gland dimensions.

Chemical Swell

Chemical swell occurs when a rubber gasket absorbs a fluid to which it’s exposed. This causes the gasket material to expand, soften, or become distorted. Absorption changes the gasket’s physical dimensions, but it also affects mechanical properties such as hardness and tensile strength. That’s why chemical swell is related to compression set and other types of gasket failure.

To prevent chemical swell, select a gasket material that resists the substances to which it will be exposed. For example, fluorosilicones can withstand jet fuel. In addition, consider whether the chemical exposure is continuous or intermittent. A gasket material that can withstand fuel splash may not be able to withstand long-term immersion, especially at high temperatures.

Thermal Degradation

Thermal degradation happens when a gasket is subjected to temperatures beyond its recommended range. Short-term extremes may not cause immediate failure, but prolonged exposure can cause materials to harden, crack, or lose their elasticity. Thermal degradation is associated with excessive heat, but extreme cold can also make some materials brittle and cause performance issues.

To prevent this form of failure, design gaskets for the full range of expected temperatures and not just ambient. Consider worst-case scenarios for both extreme heat and extreme cold. For applications that require resistance to extreme temperatures, use materials that are engineered to withstand them.

Installation Damage

Installation damage is sometimes called “pock marking” because this form of failure results in large notches on the surface of the seal. Often, overstretching the gasket material is to blame. Installation damage can also occur if an enclosure has sharp or rough surfaces that scratch or tear elastomeric components.

Designers can apply chamfers or lead-ins to housings to simply gasket installation, but assemblers need to avoid scraping the seal along an enclosure’s edges. In addition, installers must avoid stretching solid elastomers beyond 50% of their original diameter. This is especially important with door or hatch gaskets because they may not fit if they’re overstretched.

Get Expert Assistance from Stockwell Elastomerics

Contact Stockwell Elastomerics for assistance with troubleshooting a failed gasket or designing a better and more effective seal.

The post Common Gasket Failures and How to Prevent Them appeared first on Stockwell Elastomerics.

Stockwell Elastomerics supplies enclosure-level EMI/RFI shielding that also provides environmental sealing. These EMI gaskets fabricate consist of solid silicones that contain metal or metal-coated particles, or cellular silicones that are bonded to Monel wire. Silicone elastomers are inherently electrically insulating, but adding metal particles or wires makes them electrically conductive instead. Either silicone or fluorosilicone can be used as the base elastomer.

How Shielding Works and Why It Matters

EMI/RFI shielding works by blocking, absorbing, or redirecting electromagnetic energy, which travels in the form of waves. The effectiveness of an EMI/RFI shield depends on its electrical conductivity, magnetic permeability, material thickness, frequency range, and shield geometry. A shield must create a continuous conductive path around protected electronics because any seams, joints, or gaps could become leakage points.

EMI/RFI shielding is essential for maintaining electromagnetic compatibility (EMC), the ability to operate in an electromagnetic environment without causing or experiencing unacceptable levels of interference. Without proper shielding, systems may fail EMC testing, experience field failures, or interfere with other devices and equipment. Shielding keeps out external interference, but it also prevents internal circuitry from radiating electronic noise into the environment.

Electromagnetic Interference (EMI) vs. Radio Frequency Interference (RFI)

EMI interrupts, obstructs, degrades, or otherwise limits the effective performance of circuits. The “electromagnetic” refers to how electric current has electrical and magnetic forces and effects. The “interference” refers to how when an electromagnetic signal is transmitted, or propagated, that signal can be received by a circuit that is not the intended recipient. The sources of EMI are many and include, switching transients, and magnetic fields from motors.

Like EMI, RFI limits the effective performance of circuits and is propagated through conduction or radiation. However, RFI refers to interference in the RF band, typically 20 kHZ to 300 GHz. The sources of RFI include Wi-Fi, Bluetooth radios, radar systems, RF transmitters, switching power supplies that generate high-frequency harmonics, and digital electronics with fast edge rates. Like EMI, RFI can enter or exit tiny gaps in enclosures, such as between the sides and cover.

Conductive Silicones vs. Other EMI/RFI Shielding Materials

Electrically conductive silicones are not the only type of EMI/RFI shielding material. Other types of elastomers, such as EPDM, can be filled with metal or metal-coated particles; however, silicone has a wider temperature range and provides superior resistance to sunlight and ozone. Metal foils, metallized fabrics, metal alloys, and rigid shields are also used for EMI/RFI shielding. Metals have higher conductivity and reflectivity, but conductive silicones offer important advantages.

For example, conductive silicones are multi-functional materials that block EMI/RFI and keep out environmental contaminants such as dust and moisture. Unlike rigid metals, conductive silicones are also soft and elastic. This allows them to conform to uneven surfaces, fill gaps, and maintain a consistent seal even when there are tolerance variations between surfaces. Conductive silicone gaskets also require less pressure, or a lower clamping force, to create an effective seal.

Request a Free Silicone EMI Gasket Materials Touch Brochure 

Stockwell Elastomerics cuts and molds gaskets from EMI/RFI shielding materials that are sourced from supplier partners and are kept in stock or ordered on-demand. Request a free silicone EMI gasket materials touch brochure for samples, and contact Stockwell Elastomerics for help with material selection and gasket design assistance.

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Stockwell Elastomerics offers in-house 3D printing for silicone, nylon, and specialty resins—enabling customers to get their hands on functional part in days, not weeks.

How does Stockwell use 3D printing?

Our additive manufacturing team prints silicone components and precision fixturing directly in-house. Applications include:

• Rapid prototypes for fit, form, and functional testing
• Custom jigs and fixtures for assembly and inspection
• Large-format and multi-material builds for engineering and testing

Supported materials include silicone (LSR and RTV), nylon, and engineering-grade resins for high-temperature, precision, or high-impact applications.

3D Printing Equipment & Capabilities

Why engineers choose Stockwell for 3D printing prototypes

• In-house expertise: Deep knowledge of silicone and elastomeric materials
• Rapid turnaround: Parts in days, not weeks
• Functional performance: Not just aesthetic prototypes—end-use capable components
• Seamless production ramp up: Ability to quickly scale from prototypes to production, all with the same team

Get started

Accelerate your silicone part production process or inquire about our printed fixture capability.
Request a consultation or prototype today.
www.stockwell.com | service@stockwell.com | 215-335-3005

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Stockwell Elastomerics specializes in silicone gaskets and fabricates low outgassing materials for spacecraft and space vehicles, semiconductor manufacturing, defense electronics, analytical instrumentation, LED lighting, and medical devices and equipment.  Low outgassing silicones have very low levels of unreacted volatiles such as low-molecular-weight siloxanes. They’re typically tested to ASTM E595, a standard method for measuring the outgassing properties of materials.

What is Outgassing? Why Is It a Problem?

Outgassing is the release of volatiles from a material as gas molecules. In solids and liquids, there are four mechanisms: diffusion, vaporization, desorption, and permeation. No matter how it occurs, outgassing is a problem when gas molecules that escape from a material condense upon and cloud surfaces such camera lenses, sensors, and electronics. Typically, this occurs when a material is exposed to very low pressure (i.e., a vacuum) and/or high heat.

ASTM E595 and Outgassing Tests

ASTM E595 establishes outgassing tests that are used to measure the following.

• Total Mass Loss (TML) quantifies the total amount of material that evaporates or releases gases from a sample.
• Collected Volatile Condensable Material (CVCM) is the percentage of material that condenses on a cooled collector plate.
• Water Vapor Recovered (WVR) is an optional measurement for materials that absorb and release water vapor. 

ASTM E595 is associated with spacecraft and space vehicles, but it’s not limited to them.

How NASA Defines Low Outgassing Materials

Space is a near-perfect vacuum, and the surfaces of satellites and spacecraft heat up as they absorb solar radiation. In Earth orbit, surfaces facing the Sun can reach as high as 250°F (120°C). Under these low pressure and high temperature conditions, outgassing can cloud space telescopes and degrade the performance of solar arrays and avionics.

ASTM E595 provides a framework for measuring TML, CVCM, and WVR, but it’s not the last word on what constitutes a low outgassing material. For engineers who need to meet NASA requirements, it’s important to note that NASA-STD-6016 specifies that a non-metallic material (such as a silicone) must meet the following criteria to be considered low outgassing.

• ≤ 0.1% CVCM
• ≤ 1.0% TML less WVR

Other Industries That Need Low Outgassing Silicones

Low outgassing materials, especially silicones, are also used with the lithography optics and vacuum chambers in semiconductor manufacturing equipment. That’s because molecular contamination can cause pattern defects, yield loss, and optical haze. Similarly, outgassing with optics and photonics can cause fogging or haze with camera modules, laser assemblies, LiDAR systems, and night-vision optics.

With defense electronics, silicone outgassing can contaminate detector surfaces as well as precision optics. Consequently, low outgassing materials are used with radar and missile guidance systems. Analytical instruments such as mass spectrometers use these specialized materials to avoid ghost peaks. LED lighting uses them to prevent fogging. Medical devices and equipment that are sterilized in an autoclave also use low outgassing silicones for gasketing.

Stocked Materials with Low Outgassing

Stockwell’s application engineering team is available to help determine which silicone grade best aligns with your application requirements. We maintain a large inventory of select silicone foams, sponges, and solid materials to support rapid prototyping and small-quantity sampling for development builds. Stockwell supports low and high-volume production, and our manufacturing is proudly Made in USA.

Contact Stockwell Elastomerics for more information.

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There are different types of conductive rubber, but electrically conductive silicones resist moisture, contaminants, and a wide range of temperatures while allowing engineers to balance shielding performance with softness as measured on the Shore A scale.

When to Use Conductive Silicone Gaskets

Conductive silicone gaskets combine the material and performance properties of silicones with electrical conductivity. Whether they are cut or molded, these EMI seals fill gaps between lids and panels that would otherwise admit environmental contaminants and unwanted electrical interference. They also maintain their resilience under repeated compression cycles. With silicone as the base material, these gaskets can also support enclosure designs that require Ingress Protection (IP) ratings.

Depending on the filler that’s used, conductive silicone gaskets can resist galvanic corrosion, a problem in marine environments. Electrically conductive silicones are also available with UL 94V-0 flame resistance, and in compounds that meet the lettered requirements in the U.S. military’s MIL-DTL-83528 specification. Silver-coated fills provide higher levels of electrical conductivity, while silicones that contain nickel-aluminum or nickel-graphite particles are cost-effective.

When to Use Metallic Plating

Metallic plating can be used in conjunction with conductive elastomers, but not as a substitute for gasketing. Typically, metallic plating, paints, coatings, or films are sprayed onto the sides and lids of metal or plastic enclosures. They create a hard, wear-resistant surface with a uniform coating and minimal thickness. Depending on the plating material that’s used and how it’s applied, the shielding effectiveness can match or exceed that of a conductive elastomer.

Although it’s possible to plate or coat a non-conductive rubber gasket, plated metals are brittle and tend to crack or flake when a gasket is compressed. Similarly, metallic films or coatings tend to wear under compression. Plus, silicone rubber has low surface energy and may require an adhesion-promoting primer or surface treatment. Plating can improve enclosure shielding, but conductive elastomers are needed to seal-out the environment along with unwanted signals.

Shielding Performance vs. Softness

When specifying conductive elastomers, engineers need to balance shielding performance with softness. As a rule, higher filler content increases electrical conductivity but stiffens the elastomer. With EMI shielding, this is a concern because adequate compression is needed to ensure continuous conductive paths across mating surfaces. Stiffer gaskets require higher compressive forces, but this can comprise environmental sealing if an enclosure’s surfaces are uneven.

Softer conductive elastomers can accommodate misalignments and reduce stress on enclosure hardware while still providing EMI shielding and environmental sealing. They also reduce wear on mating surfaces when enclosures are opened and closed repeatedly. Softer materials can lose their resilience over time, however, and this reduces sealing effectiveness. In addition, softer materials may not be suitable for some applications because of their EMI attenuation levels.

Particle-Filled EMI Gaskets vs. Combination EMI Gaskets

EMI gaskets made of particle-filled silicones come in various durometers, but these solid elastomers are harder than combination EMI gaskets. Typically, a closed-cell silicone sponge is specified for a combination EMI gasket because of its long life, weather resistance, and functional temperature range. This gasket material contains a knitted wire cord, typically made of Monel, for conductivity.

To discuss selecting a conductive elastomer for your project, our Applications Engineering team can be reached via phone at 215-335-3005 or service@stockwell.com. Stockwell Elastomerics maintains a large inventory of silicone materials, including particle-filled silicones and fluorosilicones and combination EMI gaskets that require less compression force.

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Flash Cutting

Flash cutting can cut most high consistency silicone rubber (HCR) at speeds conducive to quick-turn prototyping. This fabrication process uses a digital knife cutting system instead of custom tooling. Consequently, Stockwell Elastomerics can turnaround prototype parts in as quickly as one day. Tolerances of +/-0.010 on small features are achievable, but flash cutting is scalable only to small or medium volume production.

Waterjet Cutting

Waterjet cutting can quickly produce samples for immediate testing. No cutting tools are required, and Stockwell Elastomerics can provide prototype parts in as quickly as one day. For custom silicone gaskets and EMI pads, the tolerances are comparable to those of flash cutting. Waterjet cutting makes intricate, accurate cuts and is scalable to mass production at small to medium volumes. It’s a good choice when steel rule die cutting or injection molding is planned for higher volumes.

Die Cutting

Die cutting is generally used for high-volume production rather than rapid prototyping. That’s because this gasket fabrication process uses a metal tool, or die, that needs to be machined. Die cutting is cost-effective when the cost of the die can be spread across many parts, but rapid prototyping usually involves very low volumes. Once the tool is made, however, die cutting is faster than water jet cutting. Yet its tolerances are less exact because the die causes edge concavity dependent on the material thickness.

Laser Cutting

Stockwell Elastomerics does not use laser cutting for rapid prototyping (or production) because of limitations with this process. Like water jet cutting, laser cutting is a tool-less process; however, laser cutting has the potential to burn or char the edges of parts. In addition, laser cutting produces fumes. Although laser cutting can be used for projects ranging from rapid prototypes to high-volume production, its tolerances and cost-scaling don’t outweigh its disadvantages.

Compression Molding

Compression molding  can be a rapid prototyping process dependent on the part size, molds can be produced in as little to two weeks to accommodate initial production runs. The standard production quantities that compression molding can support are 500 to 20,000 pieces. Certain molded materials can only be processed via compression molding, such as fluorosilicone. Generally, the molding tolerances are RMA A2 (Precision) or RMA A3 (Commercial). The cost of a compression mold is usually less than an injection mold, but there’s still tooling to pay for and wait for, which can add to the tooling lead time. That said, Stockwell has the capability to provide rapid prototype steel tooling to produce limited quantities of prototype parts quickly, sometimes cutting lead times in half.  But, because rubber compression molding is a labor-intensive activity with longer cure cycles, Stockwell Elastomerics may recommend liquid injection molding instead.

Liquid Silicone Injection Molding

Liquid silicone injection molding (LIM) has cure cycles that can take from 30 seconds up to 2 minutes. Faster cycle times support shorter lead times, but LIM requires molds that can be relatively expensive. Consequently, this molding process is generally used for high-volume production instead of rapid prototyping. Tolerances for silicone LIM vary, but tighter ARPM A2 tolerances are achievable depending on the material, tool quality, and part geometry.

Contact Stockwell Elastomerics for more information about rapid prototyping for custom silicone gaskets and EMI pads. Our Applications Engineering team is available through email service@stockwell.com or 215-335-3005.

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General Purpose Silicones and Regulatory Requirements

General Purpose Silicones have become more popular as a materials option for household products and can be found in everything from baking mats and to gym equipment to makeup applicators and automotive gaskets. Consumer-grade silicones are designed for general-purpose use, which can cover both consumer and non-consumer applications. Moreover, they may contain additives or processing aids that don’t meet regulatory requirements such as 21 CFR 177.2600 from the U.S. Food and Drug Administration (FDA). Specialty-grade silicones, which include food grade silicone rubber, are formulated to meet stringent requirements such as 21 CFR 177.2600, which covers rubber articles used repeatedly with food. These silicones can be used with commercial food processing equipment that may perform up to a hundred cycles an hour.

There are many types of specialty grade silicones, that may be utilized in various technology sector applications. For example, medical grade silicone rubbers that meets USP Class VI requirements are safe for short-term skin contact. Because they won’t leach harmful chemicals, these elastomers are used in products such as blood pressure monitors which are in cyclical contact with a patient.

Consumer vs. Non-Consumer Applications

Specialty grade silicones are not sold directly to consumers. Examples include Stockwell Elastomerics gasket tape, which is made of specialty grade silicones from Rogers Corporation or Saint-Gobain. Gasket tape is a stocked off-the-shelf item, but it has a wider operating temperature range and higher tear-resistance than the pre-packaged weatherstripping that homeowners buy from Big Box stores. The minimum order quantities (MOQs) for gasket tape are also higher because these products are made of specialized materials.

How Stockwell Elastomerics Seals with Silicone     

Stockwell Elastomerics specializes in manufacturing silicone products for industrial applications such as electrical and electronic enclosures that require dust sealing and sometimes water sealing. Our Philadelphia, Pennsylvania manufacturing facility also produces parts like seals and gaskets for food processing equipment and medical devices.

Stockwell Elastomerics inventories significant amounts of specialty grade solid silicone sheet, silicone foam, and silicone sponge and fabricates them into ready-to-install products. The lead times are longer and the MOQs are higher than for off-the-shelf consumer grade items, but raw materials and finished products are Made in USA with some small exceptions on the raw materials side

For further help determining whether a specialty grade silicone is suitable for your application, please contact our Applications Engineering team through service@stockwell.com or 215-335-3005.

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This article from Stockwell Elastomerics compares silicone tolerances to those of rigid materials. It also considers the relationship between silicones properties and dimensional tolerances. Some silicone properties can be adjusted, but even spec-grade materials have looser tolerances than metals and plastics. Silicones also vary in weight between batches.

Silicone Tolerances vs. Metal and Plastic Tolerances

Metals and plastics can be machined to tolerances as tight at ±0.01 mm. Their rigidity and predictable thermal expansion ensure dimensional stability, and their surface finish and geometry can be controlled with relative precision. Rigid plastics such as PEEK, ABS, and polycarbonate can also be injection-molded instead of machined. Cooling-related shrinkage is highly predictable, and tolerances generally range from ±0.05 mm to 0.1 mm.

Silicone tolerances are looser because these elastomers deform easily, exhibit greater batch-to-batch variability, and use different manufacturing processes (such as die cutting and liquid injection molding (LIM)). Depending on part size and geometry, silicone tolerances generally range from ±0.25 mm to 0.5 mm. Silicones are also viscoelastic, which means that they exhibit both elastic and viscous behavior when deformed.

Silicone Properties and Material Tolerances

Silicone elastomers can be customized with fillers, additives, and curing agents to modify properties such as hardness, thermal or electrical conductivity, and color. Nevertheless, silicones remain more flexible than metals and plastics. Moreover, their densities vary within a relatively narrow band. In addition, silicones expand and contract more in response to temperature changes. With their viscoelastic properties, time-dependent deformation such as stress relaxation can occur.

Because silicones deform under compression, measuring part dimensions with calipers or gauges can be imprecise. Depending on how a silicone part is handled, additional compression or stretching may occur. Slight differences in viscosity or filler dispersion during silicone molding can also affect final dimensions. Post-cure shrinkage varies by formulation, mold design, and curing conditions. Importantly, silicone shrinkage is less predictable than with injection molded plastics.

Thickness Tolerances and Batch-to-Batch Weight Variations

Thickness tolerances for silicones are usually ±0.25 mm for molded sheets or gaskets. For extruded silicone sheets, tolerances that are 10% of the nominal thickness are typical. To account for silicones’ looser tolerances, engineers sometimes specify thickness ranges instead of exact values. For best results, validate these tolerances with both functional testing and dimensional inspection.

Compared to rigid materials like metals or plastics, silicones also vary more by weight between batches. There are several reasons for this. Slight differences in filler loading or dispersion affect silicone density, and longer or hotter cures that remove volatiles reduce weight incrementally. The absorption of small amounts of moisture can also affect a silicone’s weight. Because of these factors, Stockwell Elastomerics does not weight silicone materials or provide silicone part weights.

Learn More About Silicone Tolerances

Understanding silicone tolerances is an important aspect of custom gasket design. Contact Stockwell Elastomerics via our form or service@stockwell.com for more information and ask to speak with a member of the Applications Engineering Team about how silicone tolerances may affect your application.

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This article from Stockwell Elastomerics contains key specifications for avoiding common gasket failures. It’s divided into five major areas.

• Tolerance stacks
• Stress relief
• Seal geometry
• Bonding/adhesion
• Accelerated life testing

Tolerance Stacks

Tolerance stacks, or tolerance stack-ups, are cumulative dimensional variations among mating parts. In gasketed assemblies, even small deviations can compromise seal integrity. For example, problems with tolerance stacks in an aerospace assembly can result in uneven gasket compression with fuel or hydraulic seals. Medical devices such as infusion pumps need to avoid tolerance issues that could allow micro-leaks and compromise sterility.

To prevent problems like this, perform a tolerance stack analysis early in the design phase. Use integrated computer-aided design (CAD) tools and consider worst-case scenarios rather than average values. Also, make sure to specify gasket durometer and compression ranges that can accommodate these dimensional variations. Finite element analysis (FEA) software can simulate gasket deformation under tolerance extremes.

Stress Relief

Compression and vibration cause mechanical stresses that can result in cracking or a loss of elasticity. In the aerospace industry, engine vibrations may cause fatigue at gasket interfaces. With medical devices, repeated autoclaving can expose gaskets to thermal expansion and contraction that stresses the elastomer. Silicone rubber can resist thermal cycling and absorb vibrations, but material selection alone won’t ensure sealing success.

Select gasket materials with low compression set and high resilience. Also, consider incorporating stress-relief features such as spring-loaded fasteners. In addition, avoid sharp corners or rigid clamping that can concentrate stresses. For applications with extreme temperature changes, consider the thermal expansion coefficients of each material in gasket design calculations. With enclosures, the gasket material and the housing material need to expand at or near the same rate.  Various silicones, such as heat press pads / thermal gap fillers, can accommodate this need in applications where housing materials are highly thermally conductive. This ability to match the enclosure is material selection dependent. For assistance, please contact our applications engineering team.

Seal Geometry

Seals with unique or complex geometries may compress unevenly or allow contaminants such as moisture or dust to accumulate. If O-ring grooves or gasket design lack proper dimensions, the gasket material can become distorted under high differential pressures in aircraft cabins or avionics enclosures. In medical instruments flat die cut gaskets need to be free from crevices where biofilms could accumulate. Different gasket cutting and fabricating processes may yield different cut profiles.

To ensure predictable compression, consider standardized groove designs such as AS568 for aerospace O-rings. For flat gaskets used with medical devices, design flush features that avoid crevices and support sterilization. With all elastomeric gaskets, avoid excessive compression. Depending on the elastomer and the compressive force, 20% to 30% compression may be adequate.

Bonding/Adhesion

Gaskets can be bonded to substrates with adhesives to prevent loosening, leakage, or misalignment. For example, EMI gaskets for avionics can be bonded to enclosures so that these seals remain in place despite high vibrations and significant thermal cycling. In medical diagnostic equipment, adhesive-backed gaskets that can withstand chemical cleaners or device fluids are needed.

Select adhesives that are compatible with both the gasket material and the substrate / device materials. Use peel and shear testing to validate the adhesive under application-specific conditions. If surface preparation is required, make sure to clean or roughen the substrate. For permanent bonding, consider using an adhesive to bond the elastomer to the substrate during vulcanization or other post assembly processes.

Accelerated Life Testing

Accelerated life testing (ALT) helps to predict a gasket’s long-term performance. In the aircraft industry, for example, ALT simulates high-altitude pressure cycles and exposure to jet fuel and vibrations. In the medical device industry, ALT replicates sterilization cycles, chemical cleaning, and mechanical wear.

For best results, define ALT protocols based on real-world conditions such as 10,000 pressurization cycles for an aerospace gasket or 500 autoclave cycles for a medical device seal. Monitor compression set, leakage rates, and adhesion strength (if applicable) during testing. Then, apply statistical models such as Weibull analysis to extrapolate service life from ALT data.

Discuss Potential Gasket Failures

Contact Stockwell Elastomerics to review your gasket and offer material options. Ask to speak with of a member of the Applications Engineering Team through service@stockwell.com or 215-335-3005.

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Why Silicone Is Often Used in HVAC-Related Components

Silicone foams and sponges maintain flexibility and compression set performance across a wide temperature range—typically from –60 °C to +200 °C, depending on the grade. This stability helps support consistent sealing in components exposed to:

• Rooftop or outdoor weather conditions
• Heating elements or elevated internal temperatures
• Repeated thermal expansion and contraction
• Vibration from motors, compressors, and blowers

These characteristics make silicone a practical option for certain HVAC gasketing uses, especially where long-term environmental stability is a priority.

Adhesive-Backed Silicone Gaskets for Easier Installation

Stockwell Elastomerics applies a wide range of 3M™ acrylic pressure-sensitive adhesives (PSAs) to silicone foam and sponge to assist in the installation of these gasketing materials. Adhesive-backed silicone gaskets help installers by:

• Holding the gasket in place before final compression
• Reducing installation time and alignment challenges
• Eliminating the need for liquid adhesives or temporary fixtures

This installation support is especially valuable for contractors and OEM technicians working with multi-panel enclosures, access doors, or irregular sealing geometries.

Specialty Silicone Materials Available

To support HVAC-related design requirements, Stockwell Elastomerics offers silicone materials with specific compliance or performance attributes, including:

• UL 94 V-0 flame-retardant silicone foam and sponge
• Low smoke and low toxicity silicone grades
• FDA-compliant or food-grade solid silicone for equipment used near sensitive processing areas

These materials maintain consistent mechanical properties under compression, supporting sealing reliability in equipment subject to frequent service intervals or environmental exposure.

Stocked Materials Available for Rapid Sampling

Stockwell’s application engineering team is available to help determine which silicone grade best aligns with your performance and assembly needs. We maintain inventory of select silicone foams, sponges, and solid materials to support rapid prototyping and small-quantity sampling for development builds.

If you have an upcoming project requiring silicone gasketing for HVAC or environmental sealing, Stockwell’s team can assist with material selection and manufacturability guidance.

Request a sample or speak with an applications engineer today.

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