Ball and Roller Bearings

Technical Data17.5 Fitting surface pressureTable 17.5.1 lists equations for calculating the pressureand maximum stress between fitting surfaces.Table 17.5.2 can be used to determine the approximateaverage groove diameter for bearing inner and outerrings.The effective interference, in other words the actualinterference !deff after fitting, is smaller than the apparentinterference !d derived from the measured valued for thebearing bore diameter and shaft. This difference is due tothe roughness or variations of the finished surfaces to befitted, and therefore it is necessary to assume thefollowing reductions in effective interference:For ground shafts: 1.0 2.5mFor lathed shafts : 5.0 7.0mTable 17.5.1 Fitting surface pressure and maximum stressFittingsurfacepressureMPakgf / mm 2 MaximumstressMPakgf / mm 2 Fit conditionsSolid steel shaft/inner ring fitHollow steel shaft/inner ring fitSteel housing/outer ring fitShaft / inner ring fitHousing/outer ring fitEquationCodes (units: Nkgf, mm)d Shaft diameter, inner ringE !deff d 2bore diameterP =1- ( )2dod DiHollow shaft innerdiameterDi Inner ring average groovediameterE !deff 1- (d / Di) 2 1- (do / d) 2 !deff Effective interferenceP =2 !d1 - (do / Di) 2 EElasticity factor= 208,000 MPa 21,200 kgf / mm 2 D : Housing inner diameter,bearing outer diameterE !Deff 1 - (Do / D) 2 1 - (D / Dh) 2 Do : Outer ring averageP =2 D1 - (Do /Dh) 2 groove diameterDh : Housing outer diameter !Deff : Effective interference1 + (d / Di)2Inner ring bore diameter face maximumt max = P1 – (d / Di) 2tangential stress2t max = POuter ring inner diameter face maximum1 – (Do / D) 2 tangential stressDododDDiDhTable 17.5.2 Average groove diameter (approximate expression)Bearing typeAverage groove diameterInner ring (Di ) Outer ring (Do )Deep grooveball bearingsAll types1.054d + D50.95d + 4D5Cylindricalroller bearings 1All types1.053d + D40.98d + 3D4Sphericalroller bearingsAll types2d + D30.97d + 4Dd: Inner ring bore diameter mm D: Outer ring outer diameter mm1 Average groove diameter values shown for double-flange type.5A-103