Abstract
Using the lubricant oil with relatively low viscosity, the lubrication mechanism of oil impregnated sintered bearings was discussed in the same region as the former experiment (1st Report).
It was found that the aspect of lubrication is similar to that of the former experiment with relatively high viscosity oil, i.e. through the boundary state at low speed revolution, the bearing can be driven under hydrodynamic state at about 24, 000 rpm. In the former experiment, it was found that the bearing can be driven under hydrodynamic state at about 20, 000 rpm. This difference is caused by the difference of the thickness of lubricant oil film due to the different viscosity.
In the region of low speed revolution through the high speed one, essential features of boundary lubrication of the sintered bearing were recognized. This is caused by the pressure drop of the lubricant oil film on the sliding surface because of the leakage of the pressure into the pores, although the absolute values of the friction coefficient are relatively small. Therefore, in the region as this experiment, one cannot discuss the lubrication mechanism by the values of the friction coefficient.
