Basic Load Rating and Bearing Life
2016-05-10The basic load rating is a constant stationary load which a group of apparently identical bearings with stationary outer rings can endure for a rating life of one million revolutions of the inner ring. The basic load rating of radial bearings is defined as a central radial load of constant direction and magnitude, while the basic load rating of thrust bearings is defined as a thrust load of constant magnitude in the same direction as the central axis. The load rating C of the SNH bearings listed in the dimension tables was calculated based on the method of ISO 281. The listed data will be adjusted subject to the development of our engineering and technology.
Bearing life, in a broad sense, is the period during which bearings continue to operate and fulfil their functions. This bearing life may be defined as noise life, abrasion life, grease life, or rolling fatigue life, depending on what causes loss of bearing service.
Life of a bearing depends on its functions and applications. These functions must be performed for a prolonged period. Even if a bearing is properly mounted and correctly operated, it may eventually fail to perform satisfactorily due to increase in noise and vibration, loss of running accuracy, deterioration of grease, or fatigue flaking of the rolling surfaces.
Fatigue life is calculated by the total number of revolutions during which the bearing surface will start to flake due to stress. For seemingly identical bearings which are of the same type, size, and material and receiving the same heat treatment and processing, the rolling fatigue life of them may vary greatly even they are under identical operating conditions. This is because the flaking of materials due to fatigue is subject to many other variables. Consequently, "rating fatigue life", in which rolling fatigue life is treated as a statistical phenomenon, is used in preference to actual rolling fatigue life.
Suppose a number of bearings of the same type are operated individually under the same conditions. After a certain period of time, 10% of them fail as a result of flaking caused by rolling fatigue. In this case, the total number of revolutions is defined as the rating fatigue life or, if the speed is constant, the rating fatigue life is often expressed by the total number of operating hours completed when 10% of the bearings become inoperable due to flaking.
Linqing Nine Star Bearing Science & Technology Co., Ltd
( Insulated bearing, Hybrid ceramic bearing and Brass cage DGBB)
Follow us via E-mail info@jxkjzc.com; Website www.ninestarbearing.com.
