Balance

If the component is perfectly balanced, rotation creates centrifugal force equal in all direction from the center of rotation.
Imbalance creates an unequal centrifugal force, resulting in an excessive “pull” toward the heaviest point on the component. Imbalance can be caused by excessive weight at one point, a lack of weight at one point or by a bent or dented shaft. Imbalance also creates vibration during rotation of the driveshaft.