ALPHA ACOUSTIKI Ltd.

Vibration isolators with silicon and comparison with vibration control with rubber

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Source: ALPHA ACOUSTIKI Ltd.

Vibro-SiL Silicon Vibration Control Products is our newest addition in the existing range of vibration isolators under the brand VIBRO. The constantly increased demand for a raw material that will offer increased material capabilities without reducing the vibration efficiency motivated us to create the new anti-vibration product category Vibro SiL.

The characteristic Properties of silicon Rubber compounds are presented below.

Heat & Cold resistance

Silicone rubber withstands high and low temperatures far better than organic rubbers. Silicone rubber can be used indefinitely at 150oC with almost no change in its properties. It withstands use even at 200 oC for 10.000 hours or more, and some products can withstand heat of 350 oC for short periods. Silicone rubbers are thus suitable as a material for rubber components used in high temperature environments.

Silicone rubber also has excellent resistance to cold temperatures. The embrittlement point of typical organic rubber is between -20 oC and -30 oC, compared to -60 oC to -70 oC for silicone rubbers. Even at temperatures at which organic rubber turn brittle, silicone rubber remains elastic. Some products withstand extremely low temperatures of – 100 oC and below.

Generally speaking, silicone rubber hardness when heated in air with decreasing elongation as it deteriorates; but in sealed conditions it softens as it deteriorates, and its operating life at high temperature is shorter in sealed conditions than in air.

This softening results from the degradation of the silioxane polymer. Adjusting the silicone rubber formula, using a different curing agent, and/or post curing can help prevent softening in hot, sealed conditions. Such properties are also available.

Flame retardancy

If silicone rubber is brought close to a flame, it will not ignite easily; but once ignited it will continue burning. It is possible to impart flame retardancy and/or self extinguishing properties by adding a small amount of flame retardant. Some silicone rubber products have received UL94 V-0 certification according to the UL94 (USA) standards for flammability classification. When they do burn almost no black smoke or noxious gas is produced during combustion because these products contain none of the organic halogen compounds typically found in organic polymer rubbers. They are used in consumer electronics and business equipment; in closed spaces such as aircraft, subways and building interiors. These silicone rubbers contribute to making all these environments safer.

Compression Set

When using rubber materials for gaskets that will be under compression in heat conditions, the ability of these materials to recover from compression deformation is a crucial consideration. The compression set of silicone rubber is consistent over a wide temperature range from -60 oC to + 250 oC. Although the compression set of typical organic rubber is relatively low around room temperature, it increases significantly as temperatures rise. Silicone rubbers generally require post curing. Post curing and selection of a proper curing agent are particularly recommended when using silicone rubber to make molded items for which low compression set is desired.

Vibration Absorption

The loss modulus (tan δ)* of silicone rubber is generally low, making it ill-suited for use as a vibration insulator. Products with enhanced vibration absoption performance, however, absorb vibration consistently over a wide temperature range, from -50 oC to +100 oC

* Loss modulus (tan δ) is expressed by the following equation:

(G1=storage modulus, G2=loss modulus) The larger the value of tan δ, the greater the ability of a particular material to absorb energy (vibration, etc.)

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