Vibration Isolation Principals

Reducing vibrations emanating from a machine, plant or other vibration-emitting equipment is vital for a disturbance-free operation of the machine or plant itself, as well as for its surroundings. Conversely, it is important to reduce external vibrations influencing the machine.

Therefore a distinction is made between ACTIVE isolation (which protects the surroundings from vibrations emitted by a machine, and PASSIVE isolation (in which the machine or plant itself is protected from external interference).

Mounting a machine on a vibration-isolated bedding reduces amplitudes, resulting from shock excitation, to a permissible operational level. Damping plays an important role in this as it transforms mechanical energy into heat and thus limits the amplitudes to a permissible level. It is important to select a suitable vibration isolator in order to achieve the best possible isolation effect.

Firstly, it is necessary to consider the ratio between excitation and natural frequency:

Effective vibration isolation occurs when the above ratio exceeds the value >√2. If the value is smaller, it can result in excessive increase in interference. As a rule, the aim is to achieve a ratio between 3 and 4. For particular requirements, higher values may also be realized; however these have their limitations from both a technical and economic point of view. The isolation effectiveness is calculated as follows:


In general, four different types of isolators are employed at different and sometimes overlapping frequencies:

  • Air Spring – approx. 0.6 to 3 Hz
  • Steel Spring – approx. 1.8 to 6 Hz
  • Elastomer Spring – approx. 8 to 12 Hz
  • Rubber Mat – approx. 15 to 35 Hz





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