POROUS METAL BEARINGS *

Abstract

To facilitate the proper application of porous metal bearings, engineers demand a reliable method of predicting bearing performance in order that they may check the suitability of their designs. The responsibility of meeting that demand lies with the powder-metallurgy industry as much as with the many industries that use porous metal bearings. Most of the factors that determine the performance characteristics of these bearings are sensitive to temperature, and the method proposed in this paper commences with techniques for determining the temperature rise and hence the running temperature of the bearing. The temperature rise is obtained from the power loss at the bearing and the heat dissipation of the assembly. It is not possible to calculate these without knowing the bearing dimensions, and even if the dimensions are known the power loss cannot be calculated directly because this depends upon the oil viscosity and running clearance, both of which are dependent on the temperature. However, guidance curves are given for oil viscosity and clearance, which can be used in an iterative design process that converges rapidly towards the required solution. Having predicted the running temperature, assistance is given on methods of predicting the life of the bearing according to the quality and quantity of the oil at that temperature.