How is silicone rubber used for sealing and insulation? Silicones have valuable properties, but engineers need rubber that meets specific requirements. If you’re wondering whether silicone seals, gaskets, or insulation are the right choice for your application, consider some of the uses for this versatile polymer. The examples you’ll read about aren’t the only uses for silicone, but they’re representative. Continue reading
Flame retardant rubber helps to protect people and property from the devastating effects of fire. By stopping or slowing the spread of flame, these elastomers reduce the rate and intensity of burning. They can also limit the release of smoke and toxins while increasing the amount of time that people have to escape from life-threatening situations. Applications for these specialized compounds include electronic enclosures and the interiors of buses, trains, and subways.
For engineers, it’s important to understand that all flame retardant rubber is not the same. There are different classes of flame retardants, chemicals that are added or applied during compounding. There are also different flammability standards by industry and within the same industry. For example, the mass transit industry has so many different flame, smoke, and toxicity (FST) standards that simply asking for an “FST compound” or “flame retardant rubber” risks getting you the wrong material. Continue reading
M83528 Connector Gaskets for EMI Shielding is the first in a series of technical articles about why defense contractors are sourcing EMI connector gaskets made of particle-filled silicones. For over 25 years, Elasto Proxy has custom-fabricated seals, gaskets, and insulation for the North American defense industry.
Defense contractors need conductive elastomeric gaskets that resist electromagnetic interference (EMI), provide environmental sealing, meet military specifications, and help contain project costs. Elasto Proxy custom-fabricates EMI shielding, including M83528 connector gaskets, that meet all of these requirements. Using water jet cutting, we convert particle-filled silicones, specialized elastomers that combine the electrical properties of metals with the environmental resistance of silicone rubber. We also offer various splicing and taping methods for M83528 connector gaskets.
M83528 Connector Gaskets and Particle-Filled Silicones
The shielding elastomers that Elasto Proxy custom-fabricates for M83528 connector gaskets use silicone or fluorosilicone as the base material. Silicone offers thermal stability over a wide temperature range and resists water, ozone, and ultraviolet light. With its fluorine additions, fluorosilicone adds resistance to solvents and jet fuels. Shielding elastomers are available in a range of durometers, including ultra-soft silicones. For added strength, particle-filled elastomers can be reinforced with an inner layer of conductive fabric.
Fill materials for shielding silicones and fluorosilicones include metal or metal-coated particles that provide electrical conductivity and EMI shielding. Some older part drawings still specify silver-filled products, but silver-aluminum silicones offer excellent conductivity and strong volume resistivity, an indirect measure of shielding effectiveness. Importantly, shielding elastomers with silver-coated fills cost significantly less than pure-silver products. The following table explains.
Filler Type Cost Electrical Conductivity Typical VR
Silver $$$$$ Extremely Conductive .0009 Silver-Aluminum $$$$ Super Conductive .003 Silver-Copper $$$$ Super Conductive .003 Silver-Glass $$$ Very Conductive .006 Nickel-Graphite $$ Conductive .01 Carbon Black $ Semi-Conductive 8.0
M83528 Connector Gaskets and QPL Materials
MIL-DTL-83528 (M83528) is a U.S. military specification (MIL-SPEC) for electrically-conductive, elastomeric shielding gaskets that suppress EMI and radio frequency interference (RFI). This MIL-SPEC consists of lettered sections (Types A through M) that establish minimum levels of plane wave shielding effectiveness at 10 GHz over a continuous-use temperature range. MIL-DTL-83528 also defines the base material and the fill material for each Type. As noted above, fill material is an important driver of EMI gasket costs.
Elasto Proxy custom-fabricates EMI gaskets from shielding elastomers that meet the requirements of MIL-DTL-83538 Types A, B, D, E, L, K, and M. Two of the compounds that we convert have a Qualified Project Listing (QPL) from the Defense Logistics Agency (DLA), part of the U.S. Department of Defense. These QPL listed materials have been independently tested for best attenuation level, as reported below.
The following table describes the M83528 connector gaskets that Elasto Proxy custom-fabricates.
MIL-DTL-83528 Type EMI Gasket Material Fill Material Base Elastomer Durometer (Shore A) VR (Ohms/Cm) QPL? Shielding Data? A EMI-83528-A-65 Silver-Copper Silicone 65 .0009 B EMI-83528-B-65 Silver-Aluminum Silicone 65 .001 Yes Yes
139.1 dB @ 200 MHz
D EMI-83528-D-70 Silver-Aluminum Fluorosilicone 70 .005 Yes Yes 137.4 dB @ 80 MHz D EMI-83528-D-45 Silver-Aluminum Fluorosilicone 45 .002 D EMI-83528-D-70P* Silver-Aluminum Fluorosilicone 70 N/A E EMI-83528-E-65 Silver Silicone 65 .001 L EMI-83528-L-75 Silver-Nickel Silicone 75 .001 K EMI-83528-K-80 Silver-Copper Silicone 80 .0009 M EMI-83528-M-65 Silver- Glass Silicone 65 .006
* EMI-83528-D-70P* is passivated for increased corrosion resistance.
Supporting Military Electronics and Your Informational Needs
Thank you for reading this technical article about M83528 connector gaskets. Future articles will explain how Elasto Proxy also fabricates military EMI gaskets that do not need to meet MIL-DTL-83528 requirements. We’ll also describe the cost-saving benefits of water jet cutting, splicing, and taping. Finally, other articles in this series will take a closer look at the advantages of EMI connector gaskets made from specific materials, such as ultra-soft silicones, conductive-fabric reinforced silicones, and QPL listed products.
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Technical buyers and product designers have a choice of materials for heat sink gaskets. Learn about the advantages of thermally-conducive silicone coated fabrics, and how Elasto Proxy creates custom solutions for thermal management challenges.
Computers, telecommunications equipment, and electronic devices generate significant amounts of heat. Unless this heat is dissipated, component damage and system failure can result. By establishing an effective thermal path between a heat-generating component and a metallic heat sink, thermal interface materials dissipate heat and support product life and performance. Some materials, such as thermally-conductive silicone fabrics, also provide properties that strengthen product designs. Continue reading
Technical buyers and design engineers need to evaluate all of their application requirements when specifying acoustic insulation. Sound dampening and sound absorption aren’t the same, and some acoustic materials may not be suitable for specific environments or frequencies.
Noisy equipment can cause hearing loss and result in violations that carry fines and other penalties. In North America, regulatory agencies such as OSHA, NIOSH and the Canadian Center for Occupational Health and Safety (OHS) establish workplace limits for noise exposure. Yet the fact remains that noise and hearing loss are the second most prevalent self-reported work-related injury, according to the Hearing Research Laboratory at the University of Ottawa.
Noise can also affect perceptions of product quality. That’s why some potential car buyers listen to how a vehicle’s door sounds when it closes. In a sports car, engine noise suggests speed and power. In a tractor, dump track, or military vehicle, loud engine sounds within the cab are unwanted. For technical buyers and design engineers then, noise mitigation can be about enhancing worker safety, ensuring regulatory compliance, improving the customer experience – or all of the above.
Acoustic insulation is essential, but what are some design considerations? In other words, what do buyers and designers need to know? Continue reading
Rubber weather stripping provides either static or dynamic sealing. Sealing pressure is essential, and some elastomers are more resilient than others. Technical buyers and product designers need to compare open cell and closed cell rubber, specify the durometer or hardness, and choose the right compound.
Rubber weather stripping prevents the flow of air and water between two surfaces, such as a door and door frame. Standard weather stripping may be suitable for residential use, but applications in the automotive, building and construction, and electronics industries often require a custom sealing solution. Custom-fabricated weather stripping ensures part quality while speeding installation and reducing material waste.
But what do buyers and designers need to know about weather stripping selection? Let's take a look. Continue reading
Fluorosilicone gaskets combine the high and low temperature resistance of silicones with the fuel and oil resistance of fluorocarbons. Some fluorosilicone gasket materials also resist abrasion and provide EMI shielding. Is fluorosilicone the right rubber for your gasketing application?
Fluorosilicones combine the temperature resistance of silicones with the fuel, oil, and solvent resistance of fluorocarbons. Applications for these extreme-environment elastomers include automotive, aerospace, defense, electronics, and semiconductor manufacturing.
For technical buyers and design engineers, however, choosing the right rubber can involve more than just specifying a temperature range, oil or fuel type, and industry. Is flurosilicone rubber right for your sealing and insulation application? If so, what type of fluorosilicone compound do you need? Some provide specialized properties that you might not expect. Continue reading
Particle-filled silicones are elastomeric compounds that combine the advantages of silicone rubber with the electrical properties of metals. In Part 1 of this series, you’ll learn how shielding silicones support custom EMI gaskets.
Silicone rubber is a synthetic elastomer with useful physical and chemical properties over a wide range of temperatures. Silicones resist weathering, ultraviolet light, oxidation, moisture, and many chemicals. Polydimethylsiloxane (PDMS) compounds are also flexible, permeable, and non-irritating to human skin. With applications ranging from medical gaskets and oven seals to building expansion joints and lubricants, silicone rubbers are versatile materials.Continue reading
Doug Sharpe President of Elasto Proxy
Electromagnetic interference (EMI) can disrupt military electronics and endanger the lives of the war-fighters who depend on them. The causes of EMI are numerous, and include everything from electric motors and radio transmitters to computer circuits and power lines. Electronic jamming or intentional EMI (IEMI) also concerns military planners. Military radios, cameras, sensors, and telecommunications systems can experience interruptions during battlefield conditions, or suffer permanent damage.
Several global incidents underscore these concerns. In May 2012, over 500 airplanes in South Korea experienced global positioning system (GPS) failure from electromagnetic fields that were traced to the North Korean city of Kaesong. Two years earlier, North Korea reportedly purchased truck-based systems that could jam GPS signals. IEMI weapons were used in Chechnya against the Russian military, and in Moscow against a standard telephone system.
Environmental Sealing and EMI Shielding
Military environments are especially challenging, so technical buyers and electronic designers need to select materials with the right balance of properties. Particle-filled silicones are elastomeric compounds that combine the advantages of silicone with the electrical characteristics of metals. An inert, synthetic rubber, silicone offers thermal stability over a wide temperature range and resists ozone and ultraviolet (UV) light. Silicone rubber also resists water, and can be formulated to impart electrical conductivity.
When filled with metal particles, silicone compounds can be used to fabricate gaskets that provide both environmental sealing and EMI shielding. Metal fillers include particles made of pure silver, silver-plated aluminum, or silver-plated copper. Conductive silicones that are filled with silver-plated glass, nickel-plated graphite, and carbon black are also available. Before choosing a compound, however, buyers and designers need to understand application requirements and applicable military standards.
MIL-DTL-83528C is a general specification from the U.S. Department of Defense (DOD) for electrically-conductive elastomeric shielding gaskets. Released in January 2001, it supercedes the MIL-G-83528B standard that is sometimes still referenced in data sheets. MIL-DTL-83528C sets requirements for part identifying numbers (PIN) and contains a Material Type section with lettered designations for both silicone and fluorosilicone compounds.
For example, Type B materials are silver-plated, aluminum-filled silicones that are capable of 100 dB of plane wave shielding effectiveness at 10 GHz with a continuous use temperature range from -55°C to +160°C. Conductive fluorosilicone shielding materials also carry shielding effectiveness and temperature specifications, and offer resistance to solvents and jet fuels. By understanding your sealing and shielding requirements, an EMI gasket fabricator can recommend the right material.
How Can We Help You?
Does your project require a Type B silver-plated, aluminum-filled silicone with a Qualified Products List (QPL) acknowledgement from the Defense Logistics Agency (DLA)? Elasto Proxy can source cost-effective conductive compounds for you, and them custom fabricate high-quality EMI gaskets. Our solutions providers can also source EMI shielding materials that are designed to meet the requirements of other parts of the MIL-DTL-83528C specification
For over 25 years, Elasto Proxy has custom-fabricated specialty seals and custom insulation for military and defense. How can we help you with EMI gasketing? Contact us today, or join the conversation about this blog entry on LinkedIn, Facebook, Google+, and Twitter. Elasto Proxy has a YouTube channel, too. There, you’ll find our Capabilities video, as well as other informative content. Finally, please subscribe to our free e-newsletters.
Doug Sharpe President of Elasto Proxy
Here in the northern hemisphere, the nights grow longer and the temperatures colder. In Canada, where Elasto Proxy is headquartered, the snow will arrive before December 21, the first day of winter. For building managers and maintenance personnel, the time to insulate doors and seal windows is now. Weatherstripping helps to stop air leaks, increasing occupant comfort and saving heating costs. That’s not all that that rubber weather strip can do, however.
In the southern hemisphere, maintenance crews are preparing for summer temperatures and higher cooling costs. By filling gaps and plugging leaks, sealing and insulation prevents air conditioning from escaping via drafty doors and windows. During our own summertime in the northern hemisphere, we share these same concerns. All year round and across the seasons, it’s important to protect against precipitation, too. Standard weatherstripping is available, but sometimes a custom solution is required. That's where custom weatherstripping comes in.
How Weatherstripping Works
Weather stripping is installed between two surfaces to prevent the flow of gases or liquids. In outdoor applications, the gas is usually air and the liquid is usually water. Static seals are used when there’s no relative motion between mating surfaces, such as the windows in a skyscraper. Dynamic seals are recommended when there’s motion or movement between two sealing surfaces, such as the front door and door frame in the entrance to an office building.
Standard weatherstripping is suitable for static environments, and can be supplied with an adhesive backing for ease of installation. Closed cell foams made of a medium-density neoprene are a popular choice, and provide both oil and aging resistance. Rubber weather strip that’s made of other materials, such as silicone or EPDM, are also available. For dynamic sealing and environments with changing weather conditions, compound selection is critical and a custom-fabricated seal may be required.
The Case for Custom Fabrication
Some manufacturers use off-the-shelf weather stripping to seal gaps. Often, these materials are mainly fillers that form a static seal. Since they’re not meant for dynamic sealing, however, standard weather strip may demonstrate poor compression set recovery with repeated opening and closing. That’s true not just for commercial doors, but also for car doors and the doors to electronic enclosures. Winter will soon be upon us here in Canada, but a sealing challenge from several summers ago comes to mind.
When a cold-weather manufacturer needed to supply electronic highway signs to a warm-weather customer, the supplier learned that the standard weather stripping on the metal enclosures couldn’t withstand the summer sun. That’s when the manufacturer asked Elasto Proxy for a custom-fabricated sealing solution, and we delivered high-quality rubber seals that were used to retrofit hundreds of cabinets. The supplier kept the highway contract, and the electronics inside the enclosures stayed dry.
How Can We Help You?
Do you have questions about rubber weatherstripping for doors, windows, or HVAC hatches? For 25 years, Elasto Proxy has been solving sealing and insulation challenges in a variety of industries, including construction, automotive, and electronics. By listening to all of your application requirements and analyzing all of your needs, our solutions providers can help.
Please contact us for more information, or join the conversation on our social media channels. Look for a post with a link to this blog entry on LinkedIn, Facebook, Google+, and Twitter. Elasto Proxy has a YouTube channel, too. Finally, please subscribe to our free e-newsletters. They’re a great source of information delivered right to your email inbox, and they provide links to blog entries like this one.
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