Dow Corning 3-8259 RF Silicone Foam for Compression Gaskets
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Boosting Manufacturing Productivity and Product Performance
As global competition increases, manufacturers face greater demands for products that deliver high performance, long- lasting durability, greener solutions and lower costs.
Those challenges force manufacturers to find innovative solutions at every step — component design, material selection and manufacturing. Our family of silicones for foamed-in-place gaskets last longer and are more versatile and durable than organic polymer sealants — offering you long-lasting, flexible seals that are more efficient to produce.
Dow Corning silicone foams use a hybrid technology. While they are nominally a room-temperature vulcanization (RTV) technology, they use an addition cure mechanism which is typical for high-temperature vulcanization (HTV) products. Silicone foams are designed to be dispensed and cured directly on parts to form an integrated compression gasket.
Find the Foam that Fits Your Function
Dow Corning offers you a range of silicone foam products, helping you find one that meets your application needs and helps reduce suppliers and costs. The product line includes a variety of foam densities as well as flowable and reduced flowable foams, which gives you greater control over foaming height relative to flat or inclined surfaces.
Silicone foams from Dow Corning generally have low compression set, which means they recover their original shape after being compressed. Like other silicone- based elastomers, silicone foams maintain their resiliency over a broad temperature range and resist permanent compression set.
FEATURES AND BENEFITS
- High UV stability means longer life span and excellent serviceability for components
- Excellent thermal, chemical and UV resistance
- Seals against air, water splashes, dust or moisture
- Dampens vibration and noise
- User-friendly, easy-to-handle
- 1:1 mix ratio
- Requires no external blowing agents
- Fast ambient temperature cure
- Low compression set that is retained at high service temperatures
- Stable and flexible over a wide temperature range
- Low-waste dispensing helps reduce excess material
Applications and Benefits
Two-part RTV silicone foams from Dow Corning are suitable for use to form a compression gasket or environmental seal against ambient air, splashed water, dust or moisture. They offer a cost-effective, alternative sealing solution to preformed gaskets and foam tapes in applications that require:
- Sealing of high-tolerance gaps
- Low sealing force and/or low modulus
- Damping of vibration or sound
- Automatic or robotic installation of gaskets
- High serviceability
- Fast cure at room temperature or low heat
Dow Corning silicone foams are suitable for use nearly anywhere foam tapes are used.
Typical applications include:
- Automotive lighting
- Housings for electric devices
- Timing belt covers
- Automotive “beauty covers”
- Door modules
- Ceramic hobs and their frame supports
- Outdoor lighting
- Gas boilers
Typical Properties of Dow Corning Silicone Foam
| Product Property | Dow Corning 8257 Silicone Foam | Dow Corning 8257 Black Silicone Foam | Dow Corning 3-8209 Silicone Foam | Dow Corning 3-8219 RF Silicone Foam | Dow Corning 3-8259 RF Silicone Foam | Dow Corning 3-8259 RF Dark Grey Silicone Foam |
| Viscosity (mPas) | A: 21,000 B: 12,000 | A: 20,000 B: 12,000 | A: 14,000 B: 15,000 | A: 21,000 B: 40,000 | A: 68,000 B: 63,000 | A: 64,000 B: 62,000 |
| Snaptime (sec) | 230 | 240 | 220 | 200 | 200 | 200 |
| Tack free time (min) | 8 | 8 | 7 | 6 | 7 | 6 |
| Density (kg/m³) | 140 | 150 | 250 | 300 | 330 | 330 |
| Flowability (cm) | Flowable | Flowable | Flowable | 17 | 15 | 16 |
| Cell structure (Zellen/3cm) | 35 | 30 | Fine | Fine | Fine | Fine |
| Hardness Shore 00 | 25 | 25 | 45 | 45 | 50 | 50 |
More Efficient Manufacturing
Our silicone foams are designed for efficiency in processing. The two-part silicone RTV foam is dispensed — typically with a robotic applicator — directly on the part surface
- Mixed & dispensed liquid components (no bubbles)
- Expanded & cured solid (elastomer with bubbles)
Figure 1: Mixing the components produces a reaction that releases hydrogen gas as a foaming agent. The gasket expands in its liquid stage and cures to a foamed solid elastomer within 10 minutes at room temperature. This provides a low-modulus, integrated compression seal with fine, uniform cell structure.
The mixed components expand to create the gasket and cure rapidly. The foam is typically fully expanded and ready to handle within 10 minutes at room temperature. This cycle can be accelerated by elevating the temperature.
Robotic application of the fast-curing, two-part material not only makes manufacturing faster, the precision of application equipment contributes to a reduction of waste material. In many applications, silicone foams from Dow Corning can seal high-tolerance gaps with less material than standard sealing elastomers. Their light weight also helps reduce the total weight of the final product.
The two components of Dow Corning silicone foams can be mixed either in a static or dynamic mixer, offering you additional manufacturing flexibility. A dynamic mixer is recommended, however, because the type and degree of mixing and shear can affect the density, cure and cell structure of the finished foam.
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