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Experimental Study on Frictional Force and Wear Life of Oilless Sintered-Metal Bearings for the Reliability of the Geared Motor

Oilless bearings, which are made with metal powders and then impregnated by oils, are widely used in rotating components. The friction coefficients and the oil loss rates of two types of oil-impregnated sintered-metal bearings (porous bearings, oilless bearings, or oilless metals) with varying loads were measured. One is the Cu-based bearing and the other is Fe-based bearing. The frictional forces of the bearings were measured using the journal bearing tester. By measuring the change of weight before and after sliding tests, the oil losses of oilless bearings were surveyed. Also, PV curves, which could be used to predict the life of the oilless bearing, were plotted. By observing the roundness, the cylindericity and the images of scanning electron microscopy of bearings before and after sliding tests, the tribological characteristics of the bearings were evaluated. It was found that Fe-based bearing show lower friction, more oil flow, less wear and longer life than Cu-based bearing.