>> P.22
bearing life adjustment factors a1, a2 and a3, respec-tively.Lna= a1a2a3L10 …………………………… (6)where,Lna:Corrected rating life,106 rev.a1a2 : Life adjustment factor for reliability : ife adjustment factor for special bearing propertiesa3 : Life adjustment factor for operat-ing conditionsLife adjustment factor for reliabilitya1The reliability of rolling bearings is dened as the pro-portion of bearings having a life equal to or greater than a certain specied value when a group of identi-cal bearings are operated under identical conditions. With respect to individual bearings, it refers to the probability of the life of a bearing being equal to or greater than a certain specied value.The corrected rating life for a reliability of (100-n)% can be obtained using equation (6). Table 2 shows the values of the life adjustment factor a1 for various reliabilities.Life of oscillating bearingThe life of an oscillating bearing can be obtained from ………………………………(5)rating life of oscillating bearing,106 cycles2θ: Oscillating angle, deg. (See Fig.3)P : Dynamic equivalent load,NTherefore, when the oscillating given, the basic rating frequency n1min-1 is life as represented by total oscillating hours can be obtained by substituting n1 for n in equation (2) on page A17.When 2θ is small, an oil lm cannot be formed easily between the contact surfaces of the raceway and the rolling elements. This may cause fretting corrosion. In this case, please consult IKO.pCP( )90θLOC: asic equation (5).LOC=where, 2θTable 2 Life adjustment factor for reliability a1a1.62100.530.440.330.21Reliability%909596979899LnL10L5L4L3L2L1Life adjustment factor for special bearing propertiesa2The bearing life is extended or shortened according to the quality of the material, the manufacturing technol-ogy of the bearing and its internal design. For these special bearing life properties, the life is corrected by the life adjustment factor for special bearing properties a2.The table of dimensions for IKO Bearings shows the values of the basic dynamic load rating which are determined taking into consideration the fact that bearing life has been extended by improved quality of materials and advances in manufacturing technolo-gies. Therefore, the bearing life is calculated using equation (6) usually assuming a2 = 1.Fig. 3 Oscillating motionCorrected rating lifeWhen a rolling bearing is used in ordinary applica-tions, the basic rating life can be calculated by equa-tions (1) and (2) mentioned previously.This basic rating life applies to bearings which require a reliability of 90%, have ordinary bearing properties being made of materials of ordinary quality for rolling bearings, and are used under ordinary operating con-ditions.In some applications, however, it is necessary to obtain a rating life that applies to bearings which require high reliability, have special bearing properties or are used under special operating conditions. The corrected rating life for these special cases can be obtained from the following equation by using the A19
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