Reducing the weight of industrial rotational machinery equipped with Active Magnetic Bearings (AMBs) has been shown to achieve efficient hydraulic performance at high speed rotation. It also improves space efficiency and gives cost reductions. One of our solutions for increasing rotational speed is to experimentally demonstrate the passing of the 3rd bending critical speed. In this paper, a flexible rotor supported by AMBs is introduced. The controller design for mode separation control is studied and the stability margin is evaluated according to ISO 14839-3. After checking the stability, we successfully perform the rotation test to pass a total of 5 critical speeds, i.e., 2 rigid modes and 3 bending modes, by using a modal balancing technique. This paper proves that stability and balancing are key technologies for achieving high-speed rotation.