Plane Separation, Cross Effect, What is Effect?

Plane separation is a critical term for balancing accuracy, particularly encountered in dynamic balancing operations performed in two planes. Simply put, it indicates how much the correction made to correct the imbalance in one plane affects the measurement results in the other plane when balancing in two planes. This effect is often referred to in the industry as cross effect or simply effect. In an ideal scenario, corrections made in one plane would be expected to have no effect on the other plane, but in practice, this is not possible. Therefore, a good balancing machine aims to minimize this effect, usually below 3%. A low cross effect allows the balancing process to be completed faster, more accurately, and more efficiently because the corrections in each plane do not disrupt each other.

Modern hard-bearing balancing machines use advanced mathematical models to address this issue. These machines simultaneously measure the imbalance in both planes and calculate independent correction values ​​for each plane by mathematically balancing the cross-effect. This allows the operator to effectively correct imbalance in both planes in a single operation, eliminating the need to handle each plane individually. At MBS Balance, by utilizing this mathematical plane separation technology in our machines, we guarantee high-precision balancing results for even the most complex rotors. This technology simplifies the balancing process and saves time.

The physical source of cross-effect is that a weight added to one plane changes the mass and inertia distribution of the rotor, thereby also affecting the force distribution of the other plane. Hard-bearing machines build an influence coefficient matrix using the part geometry (the axial positions of the two planes and the bearings, the correction radii) and decompose the measured forces into static and couple components to produce an independent solution for each plane. Correct plane and radius entries are a precondition for keeping cross-effect to a minimum.

An incorrectly entered plane distance or a loose fixture leads to the breakdown of the mathematical separation and to high cross-effect; this results in each correction disturbing the other. In MBS Balance systems, the plane-separation algorithm derives its calibration from geometry, so it requires no trial weight and typically keeps cross-effect below 3 percent, enabling the two-plane correction to be completed in a single step.