What Is a Vibration Isolator?
A vibration isolator is a device designed to mitigate the transmission of vibrations from vibration-generating equipment to the surrounding environment. It finds applications in settings requiring precise vibration control, such as precision manufacturing facilities and environments where optical experiments demand stability.
The effectiveness of a vibration isolator is determined by its natural frequency. Natural frequency refers to the frequency at which an object vibrates freely without external force. Lower natural frequencies provide better vibration isolation, as they are less responsive to external vibrations.
Vibration isolators often utilize air springs that can isolate vibrations in multiple dimensions, including the vertical axis. Air springs are adept at rapidly dampening vibrations due to air’s viscous resistance.
Uses of Vibration Isolators
Vibration isolators are commonly employed in industries where vibration-sensitive precision equipment is utilized, such as semiconductor and liquid crystal display manufacturing. They are used to minimize vibrations transmitted to the environment, especially when machinery like pumps or machine tools generate vibrations on a table.
In precision measurements and microscopic observations, where table vibrations or external disturbances can be detrimental, vibration isolators swiftly suppress vibrations, enhancing measurement efficiency.
Principle of Vibration Isolators
Vibration isolation entails preventing vibrations from vibrating machinery or other sources from propagating to the surrounding environment. Vibrations transmitted through gases are naturally attenuated by obstacles like walls, limiting their propagation. However, solid materials transmit vibrations differently, necessitating physical measures to curtail their transmission.
To reduce vibrations in solids, the material’s natural frequency (inherent frequency) must be kept low. When an object vibrates at its natural frequency due to external vibrations, it can experience resonance, leading to excessive vibration and potential equipment damage.
Therefore, effective vibration isolators aim to separate the transmitted vibration frequencies from the natural frequencies as much as possible. Methods like air springs and coil springs are used, with natural frequencies typically below 10 Hz. In the air spring method, compressed air within an air spring, consisting of metal fittings and a rubber membrane, helps dampen vibrations. Coil springs, on the other hand, do not require air but may result in tilting if the object’s center of gravity shifts.
Types of Vibration Isolators
Vibration isolators are classified into two main types based on their mechanisms:
1. Passive Type
Passive vibration isolators absorb input vibration energy using soft materials such as rubber or air springs. Most vibration isolators fall into this category, and some passive isolators may require an air supply, often from a compressor or factory air.
2. Active Type
Active vibration isolators actively counteract vibrations by detecting them with sensors and applying a force in the opposite direction using actuators to cancel out the vibration. Compared to passive isolators, active isolators require additional equipment like controllers and actuators but excel at isolating low-frequency vibrations below 10 Hz.
Additional Information on Vibration Isolators
Vibration Isolators vs. Vibration Dampers
Vibration isolators are devices on which vibration-generating equipment is placed to reduce the transmission of generated vibrations to the surrounding environment. Conversely, in a vibrational environment, a vibration isolator reduces incoming vibrations from the surroundings. While the terminology varies based on the role, in most cases, the device can be used for both vibration isolation and vibration reduction.
Another related term is vibration damping, which involves directly reducing the vibrations of a vibrating object. Vibration control, on the other hand, refers to the active mitigation of vibrations, often using damping devices.