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What's the difference between Vibration Damping and Vibration Isolation?


We often get questions about the difference between vibration damping and vibration isolation. Sometimes people use these terms interchangeably, but they are different. In this video TMC’s Sales and Applications Engineer, Jake Porrazzo, uses our CleanBench to demonstrate the difference between damping and isolation.

Briefly, damping is how well the tabletop prevents disturbances incident to the tabletop from propagating, in this case we are using our CleanBench top. The CleanBench top, and our optical tables, use broadband damping. These tops are constructed in such a way as to dissipate disturbances before they can reach other parts of the top. For instance, if you had a device set up on the top that created its own vibration, like a motor or switch, a highly damped top would do a good job of preventing this vibration from reaching other parts of the top? A poorly damped top would not. This is damping.

Here, Jake demonstrates damping by banging on both an undamped steel top, and a highly damped CleanBench top. You can clearly see that the CleanBench top does a much better job of converting the vibration energy to entropy before it can reach the ping pong ball. The CleanTop’s special construction is designed to dissipate this type of disturbance.

Isolation is the separation of the top from floor vibration. This is achieved (on the CleanTop) through the use of our Micro-g® pneumatic isolation legs. In this example, Jake is kicking the platform on which the CleanTop is sitting to show how the isolator legs mitigate floor vibration from traveling to the surface of the top proportionate to their transfer function. For the first kick, the legs are floating on pressurized air, as they would in normal operation. For the second kick, Jake has shut off the compressed air so the legs are not floating and are acting as rigid isolators. You can see from the accelerometer plot that rigid isolators do little to prevent floor vibration from reaching the tabletop, whereas the Micro-g legs provide excellent isolation from floor vibration.

Pneumatic isolators are typically referred to as “passive” vibration isolators because are not doing anything to sense the floor vibration. Active isolators, like our STACIS product, have sensors to sense and react to floor vibration. We will cover more about the difference between active and passive in our next video.