On-line Ferrous Debris Density monitoring in sliding area contacts under boundary lubrication regime.

Abstract

Tribology experiments with pin on disc configuration are conducted using an oil condition monitoring system. This type of condition monitoring system comprises an oil condition sensor, a moisture sensor and a ferrous debris density sensor based on the principals of Magnetometry. The experiments are conducted under boundary lubrication regime for two hydraulic oils, reference oils with additives and without additives. Controlled experimental conditions facilitate the characterisation of the evolution of wear within the sliding pair. The identification of abnormal trends during the wear process indicates the onset of fault conditions. Results show the ferrous density measurements are not directly related to the wear process because of the influence of particles deposition phenomena. Hence, a direct relationship between the real wear volume loss and the ferrous density measures is difficult to establish. Results reveal the speed of particle deposition depends to a high degree on the size of the particles, the oil viscosity and the capacity of stirring. Therefore, the characterisation of the speed of particle deposition is of relevant importance to provide a real indicator of wear progress and thus enable more information for the effective prediction of faults within machinery.