Bearing Life Marathon Electric（轴承生活马拉松电）.pdfVIP

Bearing Life Bearing life is usually expressed as the number of hours an individual bearing will operate before the first evidence of metal fatigue develops in the rings or rolling elements. In past years, four different terms were used when referring to bearing life. The terms commonly used were B10 or L10 and B50 or L50 . The terms B10 and L10 had the same meaning and the terms B50 and L50 also had the same meaning. In todays terminology the preferred term is L10 . However, L50 is sometimes used, therefore both meanings must be understood. L life: The preferred term in specifying bearing life. 10 The American Bearing Manufacturers Association (ABMA), formerly the AFBMA defines the Basic Rating Life, L10 as the bearing life associated with a 90% reliability when operating under conventional conditions, i.e. after a stated amount of time 90% of a group of identical bearings will not yet have developed metal fatigue. L10 life is also referred to by manufacturers as the minimum expected life. L life: Or average life. 50 Although the L10 life is the proper method of specifying fatigue life per the ABMA, another term is often used in the industry. The L50 or average life is accepted as the bearing life associated with a 50% reliability, i.e., after a stated amount of time, only 50% of a group of identical bearings will not yet have developed metal fatigue. L50 life equals five times the L10 life. In other words, to get a L50 life equal to a L10 80,000-hour life, you must specify the L50 life to be 400,000 hours. The following chart shows a comparison of L10 to L50 equivalents. Required L10 Equivalent L50 (avg) Life Hours Life Hours