In the Dynamic Balancing Process, Should We Support the Workpiece at the Same Support Points as in the Assembled Form?

In the dynamic balancing process, supporting the workpiece at its mounting points to best simulate real-world operating conditions is crucial for the accuracy of the results obtained. This approach accurately reflects the stresses and forces the part will be exposed to in its operating environment, ensuring that the adjustments made on the balancing machine provide real benefits. When a rotor or shaft is mounted on a machine, the support it receives from the bearing points directly affects its dynamic behavior. If the balancing process is performed from different support points, imbalances due to mass distribution may manifest differently when mounted on the machine, resulting in inadequate balancing.

Therefore, at MBS Balance, we always recommend balancing the part to be balanced using the bearing points in its actual mounting position or the areas closest to them. This approach recreates the actual operating conditions of the machine in a laboratory environment, ensuring the adjustments are permanent and effective. This minimizes vibrations generated by the part during operation, extends bearing life, and improves overall machine performance. Balancing from the correct support points is not only a balancing process, but also an engineering principle that ensures the safety and long-lasting operation of the machine.

A technical detail to watch when applying this principle is the roundness and coaxiality quality of the journal surfaces used as supports. The balancing machine can perceive geometric runout on the journal as unbalance; therefore, if the surface is defective, the journal error must be separated from the unbalance using the indexing method (turning the part 180 degrees and measuring again). If the rotor runs within its own bearings, balancing the part together with these bearings whenever possible best reflects the real condition.

For keyed shafts, the half-key convention defined in ISO 21940-32 must be followed; failing to manage the key used in balancing and the key used in assembly under the same assumption can, on its own, create out-of-tolerance vibration. MBS Balance clarifies the support geometry and key convention at the start of the project, ensuring that the result obtained in the workshop is reproduced exactly in the field.