What is imbalance and how is it corrected?
Imbalance is caused by the displacement of the mass centerline from the rotational axis which is a function of eccentricity in the distribution of the rotor mass. It is measured in units of mass and distance, e.g., gram-millimeters or gmm. Imbalance is considered in single plane modes and dual plane modes. Balancing is the correction of this mass displacement by the removal, addition or adjustment of mass to the component to compensate for centerline error. Most high speed spindles are balanced by the appropriate removal of mass. Some larger machine tool spindles have pre-drilled and tapped holes for the addition of set screws which facilitates the addition of mass to compensate imbalance. There are two general forms of balancing: “Static” and “Dynamic”. Static balancing (which is not really static) involves installing the component into a balancing machine and measuring the “heavy” point in relation to the centerline, while the part is rotating. If the required balance correction is a
