At How Many Points in the Material Should We Use Compensating Weight?

In the dynamic balancing process, the number of compensation points you use for weight is directly dependent on the part's geometry and dynamic characteristics. For standard dynamic balancing, compensation weights are typically used in at least two different planes to correct the mass unbalance of the rotating part. This approach is critical not only for eliminating unbalance at the center of mass but also for correcting moment unbalances that occur during rotation. Two-plane balancing is a sufficient and most effective solution for most rotor and shaft-type parts.

However, the balancing process may require additional points for more complex parts. For example, with wide and segmented fans or complex rotors consisting of multiple components, weights may need to be distributed across different points to completely eliminate unbalance. In such cases, using more compensation points allows for a more effective distribution of the unbalance and minimizes the final vibration. As a result, the physical structure and operating conditions of the part must be considered to determine the correct number of compensation points. At MBS Balance, we are ready to provide you with technical support to determine the most accurate compensation method and number of points.

When determining the number of correction points, two different concepts must be distinguished: the number of correction planes and the number of weight positions in each plane. While two planes are sufficient for rigid rotors, flexible rotors may require N or N+2 planes depending on the number of modes excited. On some parts, weight can only be added at certain fixed positions (fan blades, bolt holes, slot teeth); in this case, the single calculated correction vector is applied by splitting it into its components at two neighboring fixed positions (vector splitting).

Fixed-position correction is standard especially on bladed fans and propellers; the software distributes the correction at the desired angle to the existing blade angles. Thus both the target unbalance is reached and the structure of the part is preserved. MBS Balance machines support both free-angle and fixed-position (blade/hole) correction modes; they aim for the highest unbalance reduction ratio with the fewest number of points according to the part's geometry.