NSK bearing tolerances

The tolerances ofr the boundary dimensions and running accuracy of NSK rolling bearings are specified by ISO 492/199/582 (Accuracies of Rolling bearings). Tolerances are specified for the following items:

Accuracy of NSK rolling bearings	Tolerances for Dimensions Items necessary to mount bearings on shatts or in housings	Tolerances for bore and outside diameers, ringwidh and bearing width and bearing width Tolerances for inscribed and circumscribed circle diameters of rollers Tolerances for chamfer dimensions Tolerances for width variation Tolerances for tapered bore diameters
Accuracy of NSK rolling bearings	Running Accuracy items necessary to specity the runout of rotating machine parts	Permissible radial runout of inner and outer rings Permissible face runout with raceway inner and outer rings Permissible inner ring face runout with bore Permisitbe ouer Ting varaion of outside surtace generatrix inclination with face Permissible raceway to back face thickness variation of NSK thrust bearings

Regarding NSK bearing accuracy classes, besides ISO normal accuracy, as the accuracy improves there are Class 6X (for NSK tapered roller bearings), Class 6, Class 5, Class 4, and Class 2, with Class 2 being the highest in ISO. The applicable accuracy classes for each NSK bearing type and the correspondence of these classes are shown in Table below.

Bearing types			Applicable tolerance classes
NSK Deep groove ball bearings			Normal	Class 6	Class 5	Class 4	Class 2
Angular contact ball bearings			Normal	Class 6	Class 5	Class 4	Class 2
Self-Aligning ball bearings			Normal	Class 6 equivalent	Class 5 equivalent	-	-
Cylindrical roller bearings			Normal	Class 6	Class 5	Class 4	Class 2
Needle roller bearings (solid type)			Normal	Class 6	Class 5	Class 4	-
Spherical roller bearings			Normal	Class 6	Class 5	-	-
Tapered roller bearings		Metric design	Normal Class 6X	-	Class 5	Class 4	-
Tapered roller bearings		Inch design	ANSI/ABMA CLASS 4	ANSI/ABMA CLASS 2	ANSI/ABMA CLASS 3	ANSI/ABMA CLASS 0	ANSI/ABMA CLASS 00
Magneto bearings			Normal	Class 6	Class 5	-	-
Thrust ball bearings			Normal	Class 6	Class 5	Class 4	-
Tapered roller thrust bearings			Normal	-	-	-	-
Thrust spherical roller bearings			Normal	-	-	-	-
Equivalent standards (Reference)	JIS		Class 0	Class 6	Class 5	Class 4	Class 2
	DIN		P0	P6	P5	P4	P2
	ANSI/ABMA	Ball bearings	ABEC 1	ABEC 3	ABEC 5 (CLASS 5P)	ABEC 7 (CLASS 7P)	ABEC 9 (CLASS 9P)
		Roller bearings	RBEC 1	REEC 3	RBEC 5	-	-
		Tapered roller bearings	CLASS 4	CLASS 2	CLASS 3	CLASS 0	CLASS 00

JIS: Japanese Industrial Standards
DIN: Deutsch Industrie Norm
ANSI/ABMA: The American Bearing Manufacturers Association

(Reference) Rough definitions of the items listed for Running Accuracy and their measuring methods are shown in Fig.7.1, and they are described in detail in ISO 5593 (NSK Rolling Bearings-Vocabulary) and JIS B 1515(Rolling Bearings-Tolerances) and elsewhere.

Measuring methods for running accuracy

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