Hiromichi Takemura

Research Work for Clarifying the Mechanism of White Structure Flaking and Extending the Life of Bearings

Bearings used in electrical engine-driven accessories, such as alternators and air conditioner (A/C) compressor pulleys, generate flaking related to non-metallic inclusions of unusual microstructure (white structure flaking), which occurs at one-tenth to one-twentieth of the calculated bearing life. In this paper, we will describe our investigation of the mechanism of white structure flaking, and report on how we achieved extended service life of engine-driven accessory bearings by implementing an evaluation of white structure flaking based on the discovered mechanism. We verified that the tribochemical reaction of grease, and statistic electricity generated by friction between the drive belt and pulley were the main culprits of white structure flaking. White structure flaking was further augmented by hydrogen invading the bearing steel, which further impaired bearing life.

Analysis of Bearing Outer Ring Creep with FEM

With the developments is automobile and machine, rolling bearings are required to work under harder conditions of high speed and heavy load than before. Hard conditions may lead to a greater likelihood of happening of kinds of bearing problems. One example is the problem of ring creep, which may result in unusual noise and cause bearing wear. Ring creep is referred to a phenomenon that a bearing ring rotates slightly relatively to the housing or the shaft during the operation.