FUNDAMENTAL CHARACTERISTICS OF WEAR PARTICLE DEPOSITION MEASUREMENT BY AN IMPROVED ONLINE FERROGRAPHIC ANALYZER

An improved on-line ferrographic analyzer and its specific characteris tics are presented. This analyzer is very convenient for detecting wea r debris in a transparent oil pipe of a machine by using an electromag net and a photoelectric sensor with a microprocessor. To eliminate the detection error of background colour of the oil sample, the wear inde x is redefined and can be directly calculated by the microprocessor in this analyzer. This detected value can represent the covered area rat e of deposited wear debris and is able to present accurately the debri s concentration. Results show that the wear index is slightly decrease d by higher viscosity, and that the effects of a flow rate of the oil sample lower than 2 ml min(-1) on the wear index are not obvious. A si mple theory, accounting for the balance between the magnetic and fluid drag forces on the wear particles, is presented and shows very good a greement with experimental results. (C) 1997 Elsevier Science S.A.