A rotor is a body that rotates about an axis and is held by its bearing surfaces in supports. The bearing surfaces — the journals — transmit the loads to the supports through rolling-element or sliding bearings.
In a perfectly balanced rotor the mass is distributed symmetrically about the axis of rotation: for every element of the rotor there is another element located symmetrically on the opposite side. During rotation each element is acted upon by a centrifugal force directed radially, perpendicular to the axis. In a balanced rotor the centrifugal force on any element is counterbalanced by the centrifugal force on its symmetric counterpart: forces F1 and F2 are equal in magnitude and opposite in direction, and the total centrifugal force on the rotor is zero.
If the symmetry is broken, an uncompensated centrifugal force F3 appears. As the rotor turns, this force changes direction together with it. The resulting dynamic load is transmitted to the bearings and accelerates their wear. The same alternating force cyclically deforms the supports and the foundation — this is what we perceive as vibration.
Balancing is the operation of restoring the symmetry by installing counterbalancing masses. The task of balancing is to find the magnitude and the angular position of one or several correction masses.
This is exactly the calculation the Balanset-1A performs from the measured vibration and phase. More at vibromera.eu.
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