Reasons for Machine Vibration

Among the most important mechanical faults that vibration analysis can reveal are:

Imbalance: A “heavy spot” in a rotating component causes vibration when the unbalanced weight rotates around the machine’s axis, creating a centrifugal force. As machine speed increases, the effects of imbalance become greater. Imbalance can severely reduce bearing life as well as cause undue machine vibration.

Misalignment/shaft runout: Vibration can result when machine shafts are out of line. Angular misalignment occurs when the axes of (for example) a motor and pump are not parallel. When the axes are parallel but not exactly aligned, the condition is known as parallel misalignment. Misalignment may happen during assembly or develop over time, due to thermal expansion, components shifting, or improper reassembly after maintenance. The resulting vibrations may be in the direction of the rotation, along the shaft axis, or both.

Wear: As components, such as bearings, drive belts, or gears, become worn, they may cause vibration. When a roller-bearing race becomes pitted, for instance, the bearing rollers will cause a vibration each time they travel over the damaged area. A gear tooth that is heavily chipped or worn, or a drive belt that is breaking down, can also produce vibration.

Looseness: Vibration that might otherwise go unnoticed may become obvious and destructive if the component vibrating has loose bearings or is loosely attached to its mounts. Such looseness may or may not be caused by the underlying vibration. Whatever its cause, looseness can allow any vibration present to cause damage, such as further bearing wear or wear and fatigue in equipment mounts and other components.

Unwanted vibration in a machine is Energy Loss and Money Loss