At NEDC, Custom Silicone Rubber Gaskets are a common product we sell. We sell these into applications where customers need low closure force to seal medias such as water, or dust out from their enclosure. Included in that category are the Super-Soft Silicone Rubber Gaskets that are available. When I think soft gaskets, typically below 40A durometer would be considered soft. However, when I think of super-soft, in my mind I am thinking of 10A-20A Shore Durometer material. However, I do include materials a little harder durometer (35A).
Potential Issues with Silicone Sponge/Silicone Foam
Understanding the benefits of super-soft silicone rubber materials may be best to start where silicone sponge intersects with silicone rubber. Silicone Sponge/Foam are great for many sealing applications. However, there does exist some issues with some sealing applications when choosing silicone sponge/foam.
- One of the common troubles with silicone foam or silicone sponge gaskets is the fact that their tear/tensile is compromised because realistically half the material is made up of blown cells in the material. With solid silicone rubber, these numbers are improved dramatically. Tear, tensile, and elongation all will go up significantly.
- The other issue with silicone sponge/foam is the fact you cannot get it below .032” (1/32”). The reason for this is it is blown to thickness. When that happens, it is difficult to get the firmnesses reliably because of the lack of blown cells in the material. These low durometer comparable materials are great for those type situations.
These Super-Soft Silicone Gaskets allow for low-closure force while also providing a high level of tear strength. These Super-Soft Silicone Gaskets still maintain the wide temperature range that many who use silicone rubber are used to.
Applications Using Low Durometer Silicone Gaskets
Low Durometer Silicone Gasketing materials are exceptional at sealing, and ruggedizing equipment. Some applications include:
-Water Sealing
-Enclosures/Portable Devices such as IP65, IP66, and IP67 featuring dust, and water sealing.
-Ruggedizing portable devices such as tablets, or battery hatch seals, and/or digital camera lens.
What is tight tolerance rubber for silicone rubber materials?
Typically, when it comes to silicone sheet stock materials- the material I usually look at the RMA (Rubber Manufacturers Association) Tolerancing. In the case of calendared sheet material has the following tolerances:
.032” and below, +/- .007”
.040”- .060”, +/- .012”
.070”- .134” +/- .017”
.135” and over +/- .022”, given that these materials that I present below have extremely tight tolerances.
.010” +/- .002”
.020” +.003”/-.002”
.031” +/- .004”
.063” +/ .006”
.125” +/- .008”
So in essence these super-soft silicone rubber materials exhibit incredibly tight thickness tolerancing for tight closure applications.
Popular Low Durometer Silicone Rubber Products
| Product(click to download datasheet) | Manufacturer | Colors Available | Thickness Available | Durometer(Hardness Shore A) |
| BISCO HT-6210 | Rogers Corporation | Gray | .010’’-.125’’ | 10 Shore A |
| BISCO HT-6220 | Rogers Corporation | Black | .010’’-.125’’ | 20 Shore A |
| BISCO HT-6135 | Rogers Corporation | Cream | .010-0.125” | 35 Shore A |
Cutting/Lamination of Soft Silicone Gaskets
NEDC commonly laminates materials with adhesive backed tapes to aid in assembly. These include acrylic tapes such as 3M 467MP or 3M 9472. In addition, as mentioned in many other blog posts, NEDC uses waterjet cutting, and die-cutting machines to convert these gasket materials into finished custom shapes.
For more information on super-soft gaskets, please contact sales@nedc.com.