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Elasto Proxy's Sealing Solutions Blog Blog

Elasto Proxy's Sealing Solutions Blog

Elasto Proxy's Sealing Solutions Blog is the place for conversation and discussion about the design and custom fabrication of rubber and plastic components. For nearly 25 years, our family-owned company has provided high-quality, low-volume seals to a variety of industries. Doug Sharpe, Elasto Proxy's co-founder, is a former president of the International Sealing Distribution Association (ISD), a not-for-profit trade association that enhances member success through information, education, and interaction. By blogging for CR4 in this same supportive and collaborative spirit, Doug and other members of the Elasto Proxy team will share our experiences with you.

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How Silicone Rubber Is Used for Sealing and Insulation

Posted November 20, 2017 6:13 PM by Doug Sharpe

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.

Mobile Equipment

Mobile equipment manufacturers need sealing and insulation materials that can withstand demanding conditions such as engine heat, extreme outdoor temperatures, wind, water, and mud. Examples of silicone products for mobile equipment include shaft seals, spark plug caps, radiator heating hoses, O-rings, and roller gaskets.

Mobile equipment manufacturers also need floor mats, door and window seals, and thermal and acoustic insulation. Silicone rubber isn’t used for all these applications, but Elasto Proxy custom-fabricates engine bay insulation with a silicone-coated fiberglass facing and a layer of open cell silicone foam. This custom insulation is fire-resistant and withstands continuous temperatures up to 500° F.

Defense and Aerospace

Defense contractors need rubber for the hatch seals on military vehicles and for other demanding extreme environments. Sometimes, military-grade silicones are required. For example, MIL-DTL-83528 defines the requirements for elastomeric shielding gaskets. When a silicone base is filled with metal or metal-coated particles, the polymer can provide protection against electromagnetic interference (EMI).

The aerospace industry also needs silicone gaskets with specialized properties. For example, silicones that meet the requirements of the A-A-59588A specification provide strong flex-fatigue resistance – a measure of an elastomer’s ability to withstand repeated flexing or bending. Standard silicones can withstand a range of temperatures, but not all silicones resist higher levels of fatigue.

Stainless Steel and Food Equipment

Manufacturers of stainless steel and food equipment need rubber that can withstand high heat from commercial ovens and cold temperatures from freezers and refrigerators. Silicones handle these temperatures and can resist the frequent cleaning that’s required with food and beverage equipment. From baking mats to oven seals, silicone rubber also resists greases and oils.

Depending upon the specific application, manufacturers of stainless steel and food equipment may need to use rubber products made from FDA approved materials. FDA silicones are non-toxic, non-marking, and non-allergenic. They’re also tasteless, odorless, and resistant to the natural growth of bacteria. Not all food-grade silicones are FDA approved, however, so it’s important to choose compounds with care.


Infrastructure is a broad category of applications that includes building and construction projects, industrial machinery, electrical equipment, and enclosures. In residential and commercial construction, silicone rubber can be used in window seals and door seals. With other types of built structures, silicones are used in expansion joints because these elastomers allow for thermal expansion without distortion.

With their strong dielectric properties, silicones are used with cables and cable terminations, corona-resistant insulation tubing, keyboards, and contact mats. Particle-filled silicones that provide EMI shielding are used in conductive seals because metal or metal-coated particles also provide electrical conductivity. UL 94 silicones that resist the spread of fire are used in rubber gaskets for electrical enclosures.

Medical and Healthcare

Silicones for medical and healthcare applications are used in tubing for medical devices and equipment, bellows for artificial respirators, and EMI gaskets. As with food and beverage equipment, FDA approved rubber may be required. Yet not all silicones for healthcare environments require FDA approvals. Examples include the silicone door seals in walk-in bathtubs for hospital patients.

Silicones are also used with the handles for patient lifts. A metal tube can support a patient’s weight, but stainless steel is cold, hard, and sometimes slippery. Slip-on silicone foam handles support easier gripping for greater patient safety and comfort. To learn more about applications for custom-fabricated silicone products, contact Elasto Proxy.


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