POROUS METAL BEARINGS

The first suggestion that the porous products of powder metallurgy could be used as self-lubricating bearings appears to have been made sometime in the early 1920s. The idea probably originated from attempts to overcome the heat conductivity limitation of oil-soaked wooden bearings. Fortunately, the conventional bearing bronze compositions could be produced by sintering and pressing the copper and tin powders which were then available, and called for nothing spectacular in the way of presses, sintering atmospheres, or furnace equipment. Although these early products were capable of only a fraction of the duty to which porous metal bearings are subjected today, their rapid development was possible because the techniques and principles involved in their manufacture were already available from other applications of powder metallurgy. The current (1964) world production of porous metal bearings is estimated to be about eight millions per day, and is still expanding.