super precision bearings

Point ContactLine Contactrequired oil required maximum 2) required oil required maximum 2)(D-d)/2 V 1) cleanliness class filtration ratio size of cycled cleanliness class filtration ratio size ofaccording to according to particles according to according to cycledISO 4406 ISO 4572 ISO 4406 ISO 4572 particlesmm µm µm≤ 12.5 0.3 11/8 β 3 ≥ 200 10 12/9 β 3 ≥ 200 200.5 12/9 β 3 ≥ 200 13/10 β 3 ≥ 751 14/11 β 6 ≥ 75 30 15/12 β 6 ≥ 75 60> 12.5 ... 20 0.3 12/9 β 3 ≥ 200 15 13/10 β 3 ≥ 75 250.5 13/10 β 3 ≥ 75 14/11 β 6 ≥ 751 15/12 β 6 ≥ 75 45 16/13 β 12 ≥ 75 75> 20 ... 35 0.3 13/10 β 3 ≥ 75 25 14/11 β 6 ≥ 75 400.5 14/11 β 6 ≥ 75 15/12 β 6 ≥ 751 16/13 β 12 ≥ 75 75 17/14 β 12 ≥ 75 120> 35 0.3 14/11 β 6 ≥ 75 40 14/11 β 6 ≥ 75 750.5 15/12 β 6 ≥ 75 15/12 β 12 ≥ 751 17/14 β 12 ≥ 75 120 18/14 β 25 ≥ 75 200The oil cleanliness class as a measure of the probability of life-reducing particles being cycled in a bearing canbe determined by means of oil samples, e.g. through filter manufacturers and institutes. The cleanliness classwill be reached if the total oil quantity flows through the filter within a few minutes. To safely ensure a highdegree of cleanliness, flushing is required prior to bearing operation.E.g., a filtration ratio of β 3 ≥ 200 (ISO 4572) means that only 1 out of 200 particles ≥ 3 µm will pass the filter ina so-called multi-pass test. Filters coarser than β 25 ≥ 75 should not be used due to the detrimental effects on theother components within the oil circulation system.1,2)Contamination factors V apply when no larger particles of a hardness > 50 HRC are cycled in the highlyloaded contact zone.21: Guide values for contamination factor Vby the manufacturer. The life offail-safe types is usually limited bythe service life of the lubricant (seeGrease Service Life, page 146).The modified life calculation hasreplaced the traditional calculationaccording to DIN ISO 281 in thefield of super precision applications.To enable the comparisonwith earlier bearing arrangements,the equation is given below. Thedetermination of the relevant factorshas been explained in thepreceding paragraphs.CPpL h10 = ·10 660 · nL h10 = Life [h] for 10% failureprobabilityC = Dynamic load rating [kN]P = Dynamic equivalent load[kN]n = Speed [min -1 ]p = 3 for ball bearingsp = 10/3 for roller bearingsEngineeringFAG · 141