Noise, Vibration, and Harshness

    Noise, vibration, and harshness (NVH) are generated during the operation of an engine and can travel by vibrating through the structural components of the automobile. NVH will manifest itself into the vehicle cabin where it becomes a nuisance to the operator. Noise in the operation of a vehicle is classified as any undesirable sound the driver may hear and vibration is categorized into shaking or any motion of the vehicle. Lastly, harshness can be described as the reaction of the vehicle to the road and environmental conditions. 

How To Reduce NVH?

One of the main techniques currently used in automotive manufacturing to reduce sound and vibration is the application of an adhesive layer of viscoelastic material to metal or composite components that are susceptible to vibration to "dampen" noise and vibration.  Momentive SilGrip™ NVH provides absorption and isolation through its pressure-sensitive adhesive properties. 
 

Unlike Momentive SilGrip™ NVH other materials used for dampening may consist of acrylic or rubber-based adhesives.  While these types of adhesives provide sufficient damping at room temperature, the damping properties provided are significantly reduced when the temperature changes and are almost non-existent when the temperatures outside are 15-25°C. 

 

Optimizing NVH with Momentive SilGrip™

Momentive SilGrip™ NVH is a fully customizable silicone pressure-sensitive adhesive system that is designed to provide optimum sound and vibration damping performance across a much wider temperature range (-54°C  - 380°C) than traditional viscoelastic damping materials. Momentive SilGrip™ NVH also has wider peaks compared to other adhesive materials, which allows for part number consolidation or a better overall product around room temperatures. Momentive SilGrip™ provides formulators with an easier-to-use, higher performance capabilities, and a more universal solution to NVH.

The SilGrip™ NVH system consists of a silicone pressure-sensitive adhesive (SilGrip™ NVH-PSA1), a high-temperature modifier (SilGrip™ NVH-HT1), and a low-temperature modifier (SilGrip™ NVH-LT1).  By mixing SilGrip™ NVH-PSA1 with either SilGrip™ NVH-HT1 or SilGrip™ NVH-LT1, damping properties for a specific temperature range can be optimized.  The mix ratios and chart below provide a starting point for maximizing performance damping properties at a specified temperature range with SilGrip™ NVH.

PSA1 Formulation Calculator

To calculate an exact mix ratio for SIlGrip™ PSA1 enter the temperature at which you wish dampening properties to be maximized and your target solution mass into the calculator below.














The use of SilGrip™ SRC18 or BPO at 1-3% is recommended as a catalyst for cross-linking and curing SilGrip™ NVH adhesives.  In general, peak damping is reduced by the incorporated excessive catalyst.  Therefore, the minimum amount of catalyst is necessary to achieve good adhesion and should be used to optimize vibrational damping performance.

Preparation and Application of SilGrip™ NVH

The video below provides the best practices for preparing and adhering Momentive SilGrip™ NVH to your surface component. 

Additional Benefits of SilGrip™ Pressure Sensitive Adhesives

SilGrip™ pressure-sensitive adhesives not only dampen noise, vibration, and harshness properties within an operational vehicle. With their superior performance over acrylic and rubber-based adhesives, SilGrip™ also provides several properties that are useful in automotive applications including:
 
  • UV Light Resistance
  • Resistance to solvents
  • Moisture and weathering resistance
  • Formulation latitude

Summary and Conclusion

With rising demand, the reduction of NVH is a critical aspect of improving a driver's assessment of vehicle quality.  This is especially true for luxury vehicles where consumer expectations are at an all-time high. SilGrip™ NVH pressure-sensitive adhesives not only reduce NVH but are able to provide outstanding performance in the most extreme climates and harsh environments.  

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