Accuracy or Precision Grade

There are two types of precision for Ball Bearings. one is dimensional accuracy and the other is rotational accuracy. The standards that control both are written by JIS and ABMA. NMB uses JIS B1514 (ISO 492), ABMA Standard 12-2 and Standard 20. The following symbols are used in this cataloge:

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Symbol

Tolerances

Table of symbols

Inner Ring (JIS)	Outer Ring (JIS)	Flange Diameter (JIS)	Flange Width, Rotation Accuracy (JIS)
Inner Ring (ABMA)	Outer Ring (ABMA)	Chamfer Dimension of Radial Ball Bearing (JIS)

Symbol

1. Dimensions
d	Nominal Bore Diameter
D	Nominal Outside Diameter
B	Nominal Inner Ring Width
C	Nominal Outer Ring Width
r	Chamfer Dimension of Inner Ring or Outer Ring

2. Dimensional Differences
Δds	Dimensional difference of bore diameter
Δdmp	Dimensional difference of mean bore diameter in the plane
(Δdm)	Dimensional difference of mean bore diameter
ΔDs	Dimensional difference of outside diameter
ΔDmp	Dimensional difference of mean outside diameter in the plane
(ΔDmp)	Dimensional difference of mean outside diameter
ΔBs	Dimensional difference of inner ring width
ΔCs	Dimensional difference of outer ring width
ΔD1s	Deviation of a single flange outside diameter
ΔC1s	Deviation of a single width of the outer ring flange

3. Limit Values of Chamfer/Radius Dimension
rs min	Minimum dimension limit of inner ring and outer ring chamfer
rs max	Maximum dimension limit of inner ring and outer ring chamfer

4. Inequality of Dimensions
Vdp	Inequality of bore diameter in a plane
Vdmp	Inequality of mean bore diameter in a plane
VDp	Inequality of outside diameter in a plane
VDmp	Inequality of mean outside diameter in a plane
VBs	Inequality of inner ring width
VCs	Inequality of outer ring width
VCIs	Inequality of flanged width

5. Rotation Precision
Kia(Ki)	Radial runout of inner ring
Sia(Si)	Axial runout of inner ring
Sd(Sdi)	Side runout of inner ring
Kea(Ke)	Radial runout of outer ring
Sea(Se)	Axial runout of outer ring
SD(SD)	Side runout of outer ring
Seal	Chamfer Dimension of Radial Ball Bearing (JIS)
Abbreviations in parenthesis are according to ABMA definitions

Inner Ring Tolerance (For Bore diameters of less than or equal to 18 mm) according to JIS standards.

All values are specified in µm

PRECISION GRADE	BORE VARIATION				BORE RADIAL RUNOUT	SIDE RUNOUT	AXIAL RUNOUT	WIDTH VARIATION		INEQUALITY OF WIDTH
PRECISION GRADE	Δdmp		Δds		Kia	Sd	Sia	ΔBs		VBs
	UPPER	LOWER	UPPER	LOWER	MAX	MAX	MAX	UPPER	LOWER	MAX
0	0	-8	-	-	10	-	-	0	-40^*1 -120	12^1 15^2 20
6	0	-7	-	-	5^1 6^2 7	-	-	0	-40^*1 -120	12^1 15^2 20
5	0	-5	-	-	4	7	7	0	-40^*2 -80	5
4	0	-4	0	-4	2.5	3	3	0	-40^*2 -80	2.5
2	0	-2.5	0	-2.5	1.5	1.5	1.5	0	-40^*2 -80	1.5

*1: For Bore Diameters of less than or equal to 2.5 mm.
*2: For Bore Diameters of less than or equal to 10 mm.

Outer Ring Tolerance (For Outer Rings of less than or equal to 30 mm) according to JIS standards.

All values are specified in µm

PRECISION GRADE	OUTSIDE DIAMETER VARIATION				OD RADIAL RUNOUT	SIDE RUNOUT	AXIAL RUNOUT	WIDTH VARIATION		INRQUALITY OF WIDTH
PRECISION GRADE	ΔDmp		ΔDs		Kea	SD	Sea	ΔCs		Vcs
	UPPER	LOWER	UPPER	LOWER	MAX	MAX	MAX	UPPER	LOWER	MAX
0	0	-8^*1 -9	-	-	15	-	-	0	-40^*2 -120	12^2 15^3 20
6	0	-7^*1 -8	-	-	8^*1 9	-	-	0	-40^*2 -120	12^2 15^3 20
5	0	-5^*1 -6	-	-	5^*1 6	8	8	0	-40^*3 -80	5
4	0	-4^*1 -5	0	-4^*1 -5	3^*1 4	4	5	0	-40^*3 -80	2.5
2	0	-2.5^*1 -4	0	-2.5^*1 -4	1.5^*1 2.5	1.5	1.5^*1 2.5	0	-40^*3 -80	1.5

*1: For Outside Diameters of less than or equal to 18 mm.
*2: For Bore Diameters of less than or equal to 2.5 mm.
*3: For Bore Diameters of less than or equal to 10 mm.

Flange Diameter Tolerance (According to JIS).

All values are specified in µm

D (mm)		Column 1		Column 2
D (mm)		ΔD1s
More than	Less than or equal to	UPPER	LOWER	UPPER	LOWER
	10	+220	-36	0	-36
10	18	+270	-43	0	-43
18	30	+330	-52	0	-52

Notes : Apply "Column 2" in above table when the flange outer diameter surface is taken the positioning.

Flange Width Tolerance, Limiting Value and Tolerance of rotation Accuracy Related with Flange (JIS).

All values are specified in µm

D (mm)		Grade 0, 6		Grade 5, 4, 2		Grade 0, 6	Grade 5	Grade 4	Grade 2
D (mm)		ΔCIs				VCIs
More than	Less than or equal to	UPPER	LOWER	UPPER	LOWER	MAX
2.5^*1	30	0 0	-40^*2 -120	0 0	-40^*3 -80	12^2 15^3 20	5	2.5	1.5

D (mm)		Grade 5	Grade 4	Grade 2	Grade 5	Grade 4	Grade 2
D (mm)		SD1			Sea1
More than	Less than or equal to	MAX			MAX
2.5^*1 18	18 30	8 8	4 4	1.5 1.5	11 11	7 7	3 4

*1: 2.5 mm is included to the dimension's division.
*2: For Bore Diameters of less than or equal to 2.5 mm.
*3: For Bore Diameters of less than or equal to 10 mm.

Inner Ring Tolerance (For Bore diameters of less than or equal to 18 mm) according to ABMA standards.

All values are specified in µm

PRECISION GRADE	BORE VARIATION				BORE RADIAL RUNOUT	BORE RUNOUT WIDTH SIDE	AXIAL RUNOUT	INNER WIDTH VARIATION		INEQUALITY OF WIDTH
PRECISION GRADE	Δdmp		Δds		Ki	Sdi	Si	ΔBs		VBs
ABEC	UPPER	LOWER	UPPER	LOWER	MAX	MAX	MAX	UPPER	LOWER	MAX
3P	0	-5.1	+2.5	-7.6	5.1^*1 7.6	-	-	0	-127	-
5P	0	-5.1	0	-5.1	3.8	7.6	7.6	0	-25.4	5.1
7P	0	-5.1	0	-5.1	2.5	2.5	2.5	0	-25.4	2.5
9P	0	-2.5	0	-2.5	1.3	1.3	1.3	0	-25.4	1.3

*1: For Bore Diameters of less than or equal to 10 mm.

Outer Ring Tolerance (For Outer Rings of less than or equal to 30 mm) according to ABMA standards.

All values are specified in µm

PRECISION GRADE	OD VARIATION						OD RADIAL RUNOUT	OD RUNOUT WIDTH SIDE	AXIAL RUNOUT	OUTER WIDTH VARIATION		INEQUALITY OF WIDTH
	ΔDmp		ΔDs				Ke	SD	Se	ΔCs		Vcs
	ΔDmp		OPEN BEARING		SHIELDED BRG		Ke	SD	Se	ΔCs		Vcs
ABEC	UPPER	LOWER	UPPER	LOWER	UPPER	LOWER	MAX	MAX	MAX	UPPER	LOWER	MAX
3P	0	-7.6	+2.5	-10.2	+5.1	-12.7	10.2	-	-	0	-127	-
5P	0	-5.1	0	-5.1	+1	-6.1	5.1	7.6	7.6	0	-25.4	5.1
7P	0	-5.1	0	-5.1	+1	-6.1	3.8	3.8	5.1	0	-25.4	5.1
9P	0	-2.5^*1 -3.8	0	-2.5^*1 -3.8	-	-	1.3^*1 2.5	1.3	1.3^*1 2.5	0	-25.4	1.3

*1: For Outside Diameters of less than or equal to 18 mm.

Radial Ball Bearing chamfer dimension of inner ring upper and lower Limits.

All values are specified in mm

rsmin	d-Nominal Bore Diameter (mm)		rsmax
rsmin	More than	Less than or equal to	Radial Direction	Axial Direction
0.05	-	-	0.1	0.2
0.08	-	-	0.16	0.3
0.1	-	-	0.2	0.4
0.15	-	-	0.3	0.6
0.2	-	-	0.5	0.8
0.3	-	40	0.6	1
0.3	40	-	0.8	1
0.6	-	40	1	2
0.6	40	-	1.3	2
1	-	50	1.5	3
1	50	-	1.9	3