Expanded rubber has become a very popular product in the gasket industry. We are often asked for requests that use silicone sponge, which is closed cell only. Silicone foam is available in different cell structures, such as modified closed, closed, open, etc. There are many advantages to utilizing silicone sponge in various applications, including gasketing, cushioning, vibration dampening, enclosure sealing, and water sealing.
Silicone sponge is able to offer many of the same properties to that of silicone rubber. Some of these properties include ozone and UV resistance, temperature resistance, and low compression for deflection values. The compressibility of these materials is impressive; it easily allows closure to happen without extremely high pressure.
Another well-known property of silicone sponge is its feasibility of meeting UL 94 requirements such as V0 and below. The closed cell structure of the sponge is important under the pressure of water. These closed-off cells prevent the water from intruding into the aggregate structure of the sponge and keep the integrity of the seal against water. There is some contention on what exactly closed-cell sponge/foam is, but usually less or equal to 5% absorption is a good rule of thumb. These closed cells play a large part in the density of the material.
It is well known that silicone sponge comes in a variety of densities, which range from Extra Soft to Extra Firm. The density and firmness play an integral role in how well the gasket compresses, and how well the gasket absorbs shock. Silicone sponge has a lot of different specifications that may be applicable in a given situation, such as AMS 3195, AMS 3196, ASTM D6576, MILR6130, and others.
The availability of silicone sponge material is virtually ubiquitous, with it being present industry wide. Most silicone sponges are provided with a textured fabric finish but may vary depending on part geometry and other variables. Although the natural red is the typical color for silicone sponge, other colors are available upon request, such as grey, black, brown, blue, and white. There are many thicknesses of silicone sponge available, ranging from .032″ to 2.0″ thick. Some popular commercial sponges include Norseal R10450, R10460, R10470, and R10480.
Lastly, some silicone sponges are available as “food grade”, meaning they are compliant with FDA CFR 177.2600. NEDC regularly converts silicone sponge products through die cutting and waterjet cutting. As with almost all of the materials that NEDC converts, a silicone or acrylic PSA is available on one side or both sides upon request. Finally, silicone sponge extrusions can be supplied by NEDC at cut-to lengths, or in plain cord stock. For more information concerning silicone sponge products or gaskets/seals made of silicone sponge please contact firstname.lastname@example.org.