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Fatigue life of the 6206 deep groove ball bearings has been evaluated under various thin lubricant film conditions. Endurance testing demonstrates that the fatigue life is remarkably longer than previous formal experiments. In addition, examination of flaked areas showed some to have subsurface origins, even after testing with extremely thin lubricant films. Longer fatigue life has been attributed to improvements in bearing steel quality, as well as improvements in the surface roughness of the ball bearing raceways. With thin lubricant films, the film parameter Λ, and the roughness profile have a greater influence on ball bearing fatigue life. Qualitative analysis of the rolling contact surfaces of some of the bearings after test has been carried out, and the formation of oxidized and carbonated films has been detected. These films can be considered to be contributors to longer fatigue life.

High speed precision ball bearings, like those used in machine tool spindles, can have serious problems associated with spin or gyroscopic moment of the rolling elements. The use of low density, silicon nitride ceramic rolling elements reduces these problems. This report presents performance test results of bearings with silicon nitride balls, and steel balls, in a high speed turbine application, using oil jet, and oil mist lubrication methods.

Recently, the performance of automobiles and industrial machines has improved remarkably. Bearing performance requirements have also increased. One of the performance requirements for bearings is increased bearing life in contaminated lubrication which contains wear debris. The bearing failure modes in contaminated lubricant are peeling caused by debris, and/or surface-initiated flaking caused by dent. Bearing life is increased by optimizing the surface hardness and the amount of retained austenite. Based on these results, a new bearing was developed, which showed ten times longer life than conventional bearings in contaminated lubrication.

Operating temperatures in many bearing applications exceed 100 °C. Conventional bearing steel (SAE52100,SAE5120,Etc.) will begin to experience a reduction in life due to dimensional instability, and reduced surface hardness, at these temperatures. High speed tool steel (such as AISI-M50) can operate in temperatures up to 300°C but is very costly. SAE52100 can be heat stabilized up to 300°C to improve the dimensional stability, but this process can severely decrease the surface hardness and fatigue life. There are many applications where the high operating temperature is greater than 100°C but less than 200°C. A new material has been developed, based on SAE52100, with improved dimensional stability, and surface hardness, for this medium operating temperature range.