An experimental and theoretical approach of a pinned and a conventional ball bearing for active magnetic bearings

The magnetic bearing rotors are present nowadays in many industrial applications. However, a damage or a malfunctioning of the magnetic bearing can produce a dangerous high lateral vibration.Backup bearings hold them to protect the machine integrity. The present study investigates the effectiveness of a pinned bearing on a horizontal rotor compared with a conventional rolling bearing. Experimental tests have been conducted; a mathematical model to describe the motion is then developed and validated numerically. It is shown that both the simulation and the test rig are in good agreement with each other and that the pinned bearing is able to reduce the interval of impacting velocities. The experimental set up is able to gather data fast enough to observe the dynamics and the forces acting on the structure. The orbits and the magnitudes of the impact forces are the key elements to assess the validity of the pinned in contrast to the rolling one as a relevant type of backup bearing.