State-of-Art of Metal Debris Detection in Online Oil Monitoring

Metal debris detection technology in online oil monitoring has drawn significant industrial attention recently since it can provide information about wear, lubrication and friction conditions of friction pairs. In the paper, the principles of several types of metal debris sensors based on photoelectric or imaging, X-ray luminescence spectrum, ultrasonic detection and electric impedance measurement are reviewed. Especially, the inductive debris sensors which gain advantages of simple structure, complete flow measuring and the ability to distinguish ferromagnetic and non-ferromagnetic metal particles, have received extensive attention. The developing progress, detection principle, typical sensor structure, and industrial applications are presented in detail. We also provided the prototype of debris sensor we developed and the performance and application in bearing health status evaluation and remain life prediction. Finally, the main problems confronted and the development trend for debris sensor using in industrial applications are also proposed.