Publication

In order to protect the global environment, low torque and long life of rolling bearings are required. To improve those bearing performances, understandings of practical bearing lubrication conditions (e.g., thickness and breakdown ratio of oil films) are very important. Usually, to measure oil film thickness in EHD (elastohydrodynamic) contacts, optical interferometry methods have been utilized. It is, however, difficult to apply them to measurements for practical bearings because visible lights cannot be transmitted through metal bodies. Recently, the electrical impedance method has been developed, which can measure the thickness and breakdown ratio of oil films simultaneously by applying an alternating voltage to the contact and measuring the modulus and phase of the impedance as a response. In this study, simultaneous measurements of thickness and breakdown ratio of oil films in practical bearings were conducted by using the electrical impedance method.