Controlling Vibration in Heavy Machinery
The components of heavy machinery aren’t well-known by those outside of the industry. Few have heard of grease fittings, the metal pieces used to feet lubricant into machinery under high pressure, drill bushings, which help support cutting tools, deburring tools, which remove rough edges and raised bumps on workpieces after construction, or vibration control systems, which allow precision industrial processes to be executed without the impact of vibration.
Vibration control systems are essential to the work of any machine performing precision tasks. For example, the production of semiconductor wafers requires that the machines used for the photolithography steps be completely free of vibrations in order to avoid blurring of the sub-micrometre features. There are two major types of vibration control systems: active and passive.
Passive Vibration Control Systems
Passive techniques make use of vibration pads and vibration mounts. Typically made from elastomers, rubber, or cork, vibration pads absorb shock without transferring it and are used under leveling pads to ensure that they don’t move out of place. Mounts, on the other hand, are used to secure loads so that they don’t vibrate unnecessarily. Bonded mounts, compression machinery mounts, cupmounts, neoprene compression mounts, rectangular mounts, sandwich mounts, spring mounts, and vibration insulator strips can all be used to secure components and avoid unnecessary vibration.
Active Vibration Control Systems
A typical active vibration control system makes use of several components. These include:
- A large platform suspended by several active drivers. These drivers may use voice coils, hydraulics, pneumatics, piezo-electric, or other techniques.
- Three accelerometers measuring acceleration in three degrees of freedom.
- An electronic amplifier system that both amplifies and inverts the signals from the accelerometers.
- In very large systems, pneumatic or hydraulic components providing high driver power may be used.
Vibration control systems are essential to the proper functionality of many machinery units used on a regular basis. By applying force in an equal and opposite fashion, active systems can maintain a vibration-free platform for a precision industrial process.