super precision bearings

LUBRICATIONGrease LubricationGrease Service LifeThe grease service life is the timeover which proper bearing functionis sustained by a particularquantity of grease. It depends on• grease quantity• grease type• bearing type• speed• temperature• installation, operating and environmentalconditions.In many applications of super precisionbearings, the grease servicelife is the decisive factor for the lifeof the bearing arrangement incomparison to the bearing fatiguelife. It can be determined from Diagram26 which applies to highspeedgreases. Unfavourable operatingand environmental conditions,including humidity, vibrationor air flow through the bearings,have to be taken in considerationif applicable.50 00030 00020 00010 000F 10[h] 5 0003 0002 0001 0000.07 0.10 0.15 0.20 0.30 0.50 0.70 1.0 1.5k f ·n·d m [min -1 · mm · 10 6 ]26: Grease Service Life F 10Rolling elements of steelRolling elementsof ceramicsk f = 1 for N10 and N19k f = 2 for NN30 and NNU49k f = 0.75 for spindle bearingswith a contact angleof 15° (C)k f = 0.90 for spindle bearingswith a contact angleof 25° (E)k f = 2.50 for 2344 / 2347k f = 2.50 for 7602 / 7603 / BSB /DBSBk f = 90 for indexing table bearings(cylindrical roller thrustbearingsn = speedd m = bearing pitch circle diameter(d m = mean bearingdiameter: D + d )2FAG · 146