NTN Technical Information Series PDF's

1 A-22 Technical TolerancesBearing tolerances; , dimensional accuracy, runningaccuracy, etc., are regulated by standards such as ISO andJIS. For dimensional accuracy these standards prescibetolerances and allowable error limitations for those boundrydimensions (bore diameter, outside diameter, width, assembledbearing width, chamfer, and taper) necessary when installingbearings on shafts or in housings. For machining accuracy thestandards provide allowable variation limits on bore, mean bore,outside diameter, mean outside diameter and raceway widthor wall thickness (for thrust bearings).

2 Running accuracy isdefined as the allowable limits for bearing runout. Bearingrunout tolerances are included in the standards for inner andouter ring radial and axial runout; inner ring side runout withbore; and outer ring outside surface runout with and allowable error limitations are established foreach tolerance grade or class. For example, JIS standard B1514 (tolerances for rolling bearings) establishes five toleranceclassifications (classes 0, 6, 5, 4, 2).Starting with class 0 (normal precision class bearings), thebearing precision becomes progressively greater as the classnumber becomes comparison of relative tolerance class standards betweenthe JIS B1514 standard classes and other standards is shownin the comparative Table indicates which standard and tolerance class isapplicable to each bearing Comparison of tolerance classifications of national standardsStandardTolerance ClassBearing TypesJapanese IndustrialClass 0 StandardJIS B 1514 Class 6 XClass 6 Class 5 Class 4 Class 2 All typesNormal classISO 492 Class 6 XClass 6 Class 5 Class 4 Class 2

3 Radial bearingsInternationalISO 199 Normal classClass 6 Class 5 Class 4 Thrust ball bearingsOrganization forTapered rollerStandardizationISO 578 Class 4 Class 3 Class 0 Class 00bearings (Inch Series )Precision instrumentISO 1224 Class 5A Class 4A bearingsDeutsches Institutfur NormungDIN 620P0P6P5P4P2 All typesRadial bearingsANSI/AFBMAABEC-1 ABEC-3 ABEC-5 ABEC-7 ABEC-9(Except taperedStd. 201)RBEC-1 RBEC-3 RBEC-5roller bearings)American NationalANSI/AFBMAT apered roller bear- standards InstituteStd. KClass NClass CClass BClass Aings (Metric Series )(ANSI)ANSI B rollerAFBMA Std.

4 19 Class 4 Class 2 Class 3 Class 0 Class 00bearings (Inch Series )Anti-Friction BearingPrecision instrumentManufacturersANSI/AFBMA__Class 5P Class 7 Pball bearings(AFBMA)Std. 3 PClass 5T Class 7T Class 9P(Metric Series )Precision instrumentANSI/AFBMAC lass 5P Class 7 Pball bearingsSts. Class 3 PClass 5T Class 7T Class 9P(Inch Series )1) ABEC is applied for ball bearings and RBEC for roller :1. JIS B 1514, ISO 492 and 199, and DIN 620 have the same specification The tolerance and allowance of JIS B 1514 are a little different from those of AFBMA Bearing types and applicable toleranceApplicableToleranceBearing TypestandardApplicable tolerancetableDeep groove ball bearingclass 0class 6class 5class 4class 2 Angular contact ball bearingsclass 0class 6class 5class 4class 2 Self-aligning ball bearingsclass 0 Cylindrical roller bearingsISO 492class 0class 6class 5class 4class 2 Table roller bearingsclass 0class 6class 5class 4 Spherical roller bearingsclass 0 TaperedmetricISO

5 492class 0,6X class 6class 5class 4 Table Std. 19class 4class 2class 3class 0class 00 Table seriesANSI/AFBMA Kclass Nclass Cclass Bclass ATable ball bearingsISO 199class 0class 6class 5class 4 Table B-219 Thrust roller bearingsNTN standardclass 0class 6class 5class 4 Table 2 Spherical roller thrust bearingsISO 199class 0 Table direction angularcontact thrust ball bearingsNTN standard class 5class 4 Table following is a list of codes and symbols used in the bearingtolerance standards tables. However, in some cases the codeor symbol definition has been abbreviated.

6 (1) Dimensiond: Nominal bore diameterd 2 : Nominal bore diameter (double direction thrustball bearing)D: Nominal outside diameterB: Nominal inner ring width or nominal centerwasher heightC: Nominal outer ring width1)Note 1) For radial bearings (except taperedroller bearings) this is equivalent tothe nominal bearing : Nominal bearing width of single row taperedroller bearing, or nominal height of singledirection thrust bearingT1: Nominal height of double direction thrust ballbearing, or nominal effective width of innerring and roller assembly of tapered rollerbearingT2: Nominal height from back face of housingwasher to back face of center washer ondouble direction thrust ball bearings, ornominal effective outer ring width of taperedroller bearingr: Chamfer dimensions of inner and outer rings(for tapered roller bearings, large end of innerrilng only)r1.

7 Chamfer dimensions of center washer, orsmall end of inner and outer ring of angularcontact ball bearing, and large end of outerring of tapered roller bearingr2: Chamfer dimensions of small end of inner andouter rings of tapered roller bearingA-24 Technical Data(2) Dimension deviation ds: Single bore diameter deviation dmp: Single plane mean bore diameter deviation d2mp: Single plane mean bore diameter deviation(double direction thrust ball bearing) Ds: Single outside diameter deviation Dmp: Single plane mean outside diameter deviation Bs: Inner ring width deviation, or center washerheight deviation Cs: Outer ring width deviation Ts: Overall width deviation of assembled singlerow tapered roller bearing, or height deviationof single direction thrust bearing T1s: Height deviation of double direction thrust ballbearing, or effective width deviation of rollerand inner ring assembly of tapered rollerbearing T2s: Double direction thrust ball bearing housingwasher back face to center washer back faceheight deviation, or tapered roller bearingouter ring effective width deviation(3) Chamfer boundryrs min.

8 Minimum allowable chamfer dimension forinner/outer ring, or small end of inner ring ontapered roller bearingrs max : Maximum allowable chamfer dimension forinner/outer ring, or large end of inner ring ontapered roller bearingr1s min : Minimum allowable chamfer dimension fordouble direction thrust ball bearing centerwasher, small end of inner/outer ring ofangular contact ball bearing, large end ofouter ring of tapered roller bearingr1s max : Maximum allowable chamfer dimension fordouble direction thrust ball bearing centerwasher, small end of inner/outer ring ofangular contact ball bearing, large end ofouter ring of tapered roller bearingr2s min : Minimum allowable chamfer dimension forsmall end of inner/outer ring of tapered rollerbearingr2s max : Maximum allowable chamfer dimension forsmall end of inner/outer ring of tapered rollerbearing(4) Dimension variationVdp: Single radial plane bore diameter variationVd2p: Single radial plane bore diameter variation(double direction thrust ball bearing)Vdmp.

9 Mean single plane bore diameter variationVDp: Single radial plane outside diameter variationVDmp: Mean single plane outside diameter variationVBs: Inner ring width variationVCs: Outer ring width variation(5) Rotation toleranceKia: Inner ring radial runoutSia: Inner ring axial runout (with side)Sd: Face runout with boreKea: Outer ring radial runoutSea: Outer ring axial runoutSD: Outside surface inclinationSi: Thrust beaing shaft washer raceway (orcenter washer raceway) thickness variationSe: Thrust bearing housing washer racewaythickness variationA-25A-26 Technical DataTable Tolerance for radial bearings (Except tapered roller bearings)Table (1) Inner ringsNominal bore diameter dmpVdpddiameter Series 7,8,9diameter Series 0,1diameter Series 2,3,4(mm)class 0 class 6 class 5 class 4 1)class 2 1)class 0 class 6 class 5 class 4 class 2class 0 class 6 class 5 class 4class 2class 0 class 6 class 5 class 4 class lowhigh lowhigh )

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