Investigation of the Voltage-Induced Damage Progression on the Raceway Surfaces of Thrust Ball Bearings

Abstract

In the course of the electrification of powertrains, rolling element bearings are increasingly subject to electrical damage. In contrast to mechanically generated pittings, voltage-induced surface damage is a continuous process. Though several approaches for the description of the damage state of a bearing are known, a generally accepted quantification for the bearing damage has not been established yet. This paper investigates surface properties, which can be used as a metric damage scale for the quantification of the electric bearing damage progression. For this purpose, the requirements for suitable surface properties are defined. Afterwards, thrust ball bearings are installed on a test rig, with constantly loaded mechanically and periodically damaged electrically in multiple phases. After each phase, the bearings are disassembled, the bearing surfaces are graded and measured for 45 different standardized surface properties. These properties are evaluated with the defined requirements. For the ones meeting the requirements, critical levels are presented, which allow for a quantified distinction between grey frosting and corrugation surfaces. These values are compared with measurements presented in the literature showing that the identified surface properties are suitable for the quantification of electrical bearing damages.

The Influence of Load and Speed on the Initial Breakdown of Rolling Bearings Exposed to Electrical Currents

“…Figure 1 shows the chronological test sequence: first, each test bearing is run in to reduce manufacturing-related roughness peaks and, thus, produce comparable initial conditions. In addition, this achieves uniform electrical lubricant properties, which may exhibit variations while running-in [22]. During the first half of the run-in phase, a pure radial load of F rad = 4000 N is set for 3 h. Subsequently, an axial force of F ax = 2000 N is additionally applied for a further three hours, so that the raceway area of the outer ring relevant for all test points has been run in under load.…”

Individual Feature Selection of Rolling Bearing Impedance Signals for Early Failure Detection

“…This needs to be avoided for sensory usage of the impedance measurement method. Figure 2 gives an overview of the three conditions [10,[17][18][19]. Gemeinder and Barz enhance the model by initiating a factor k r considering the influence of the border zone [14,15]:…”

“…This needs to be avoided for sensory usage of the impedance measurement method. Figure 2 gives an overview of the three conditions [10,[17][18][19].…”

Effect of Harmful Bearing Currents on the Service Life of Rolling Bearings: From Experimental Investigations to a Predictive Model

“…Depending on the circumstances, these discharges can lead to diverse forms of damage to rolling bearings [14]. In the case of full-film lubrication, EDM can occur and the temperatures in an arc can peak at up to 3000 K, which not only melts but also vaporizes parts of the material near the surface and has the potential to significantly alter the surface roughness [15,16]. As described by Furtmann [8,14,17], the short-term melting with consecutive oil-quenching alternates with repeated over-rollings, creating a "grey frosted" surface.…”