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Miniature & small ball bearings

Tolerance and precision grade

Rolling ball bearings have classes, and JIS and ABMA specify tolerances and tolerance values for each class. MinebeaMitsumi's products are based on JIS B 1514-1, -3, ABMA 12.2 and 20.
The main symbols used in the specification are as follows.

Tolerance and tolerance value

  • ■Dimensions
  • d :Nominal bore diameter
  • D :Nominal outer diameter
  • D1 :Nominal outer ring flange outer diameter
  • B :Nominal Inner Ring Width
  • C :Nominal Outer Ring Width
  • r :Nominal chamfer dimensions of inner ring or outer ring
  •  
  • ■Dimensional Differences
  • Δds :Dimensional difference of actual bore diameter
  • Δdmp:Dimensional difference of average bore diameter in the plane
  • (Δdm):Dimensional difference of average bore diameter
  • ΔDs :Dimensional difference of actual outer diameter
  • ΔDmp:Dimensional difference of average outer diameter in the plane
  • (ΔDm):Dimensional difference of average outer diameter
  • ΔBs :Dimensional difference of actual inner ring width
  • ΔCs :Dimensional difference of actual outer ring width
  • ΔD1s :Dimensional difference of actual outer ring flange outer diameter
  • ΔC1s :Dimensional difference of actual outer ring flange width
  •  
  • ■Chamfer
  • rs  :Actual chamfer dimensions of inner ring and outer ring
  • rs min:Minimum value of rs
  • rs max:Maximum value of rs
  • ■Inequality of Dimensions
  • VBs :Inequality of inner ring width
  • VCs :Inequality of outer ring width
  • VC1s:Inequality of flanged outer ring width
  •  
  • ■Rotation Precision
  • Kia(Ki) :Radial runout of inner ring
  • Sia(Si) :Axial runout of inner ring
  • Sd(Sdi):Perpendicularity of inner ring side surface with respect to the inner diameter axis
  • Kea(Ke):Radial runout of outer ring
  • Sea(Se):Axial runout of outer ring
  • SD(SD):Perpendicularity of outer ring outer diameter surface with respect to the side surface
  • SD1    :Perpendicularity of outer ring outer diameter surface to flange back
  • Seal    :Axial runout of outer ring flange back surface
  • Remark ( ) is defined by ABMA.
  • Above is only for radial ball bearing.

Excerpt from JIS B 1514-1

Inner ring tolerance and tolerance valued≦18 mm

(Unit : μm)

Grade Dimensional difference Radial Runout Perpendicularity Axial runout Dimensional difference of width Inequality of width
Δdmp Δds Kia Sd Sia ΔBs VBs
Upper Bottom Upper Bottom MAX MAX MAX Upper Bottom MAX
Grade 0 0 -8 - - 10 - - 0 - 40*1
-120
12*1
15*2
20
Grade 6 0 -7 - - 5*1
6*2
7
- - 0 - 40*1
-120
12*1
15*2
20
Grade 5 0 -5 - - 4 7 7 0 - 40*2
- 80
5
Grade 4 0 -4 0 -4 2.5 3 3 0 - 40*2
- 80
2.5
Grade 2 0 -2.5 0 -2.5 1.5 1.5 1.5 0 - 40*2
- 80
1.5

*1 Applicable to those with inner diameter of 2.5 mm or less.
*2 Applicable to those with inner diameter of 10mm or less.

Outer ring tolerance and tolerance value D≦30 mm

(Unit : μm)

Grade Dimensional difference Radial runout Perpendicularity Axial runout Dimensional difference of width Inequality of width
ΔDmp ΔDS Kea SD Sea ΔCs VCs
Upper Bottom Upper Bottom MAX MAX MAX Upper Bottom MAX
Grade 0 0 -8*1
-9
- - 15 - - 0 - 40*2
-120
12*2
15*3
20
Grade 6 0 -7*1
-8
- - 8*1
9
- - 0 - 40*2
-120
12*2
15*3
20
Grade 5 0 -5*1
-6
- - 5*1
6
8 8 0 - 40*3
- 80*4
5
Grade 4 0 -4*1
-5
0 -4*1
-5
3*1
4
4 4 0 - 40*3
- 80*4
2.5
Grade 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*4
1.5

*1 Applicable to those with outer diameter of 18 mm or less.
*2 Applicable to those with inner diameter of 2.5 mm or less.
*3 Applicable to those with inner diameter of 10 mm or less.
*4 Applicable to those with inner diameter of 18 mm or less.

Tolerance of outer ring flange outer diameter

(Unit : μm)

D1 Non-positioning flange
(mm) ΔD1s
Over Incl. Upper Bottom
10 +220 -36
10 18 +270 -43
18 30 +330 -52

Remarks : Contact us when using the flange outer diameter surface for positioning.

Tolerance and tolerance value of flange width and tolerance value of flange-related rotation precision

(Unit : μm)

D Grade 0, Grade 6 Grade 5, Grade 4, Grade 2 Grade 0, Grade 6 Grade 5 Grade 4 Grade 2
(mm) ΔC1s VC1s
Over Incl. Upper Bottom Upper Bottom MAX
2.5*1 30 0
-40*2
-120
0 -40*3
-80
12*2
15*3
20
5 2.5 1.5

Unit : μm

D Grade 5 Grade 4 Grade 2 Grade 5 Grade 4 Grade 2
(mm) SD1 Sea1
Over Incl. MAX MAX
2.5*1
18
18
30
8
8
4
4
1.5
1.5
11
11
7
7
3
4

*1 Outer diameter 2.5 mm is included in this dimension division.
*2 Applicable to those with inner diameter of 2.5 mm or less.
*3 Applicable to those with inner diameter of 10mm or less.

Excerpt from ABMA 20

Inner ring tolerance and tolerance value d≦18 mm

(Unit : μm)

Grade
ABEC
Δdmp Kia Sia ΔBs VBs
Upper Bottom MAX MAX Upper Bottom MAX
1 0 -8 10 15*1
20
0
0
- 40*1
-120
12*1
15*2
20

*1 Applicable to those with inner diameter of 0.6 mm or more, 2.5 mm or less.
*2 Applicable to those with inner diameter of 10 mm or less.

Outer ring tolerance and tolerance value D≦130 mm

(Unit : μm)

Grade
ABEC
ΔDmp Kea Sea ΔCs VCs
Upper Bottom MAX MAX Upper Bottom MAX
1 0 -8*1
-9
15 15*2
20*1
25
0 - 40*3
-120
12*3
15*4
20

*1 Applicable to those with outer diameter of 18 mm or less.
*2 Applicable to those with outer diameter of 6mm or less.
*3 Applicable to those with inner diameter of 2.5 mm or less.
*4 Applicable to those with inner diameter of 10mm or less.

Excerpt from ABMA 12.2

Inner ring tolerance and tolerance value d≦18 mm

(Unit : μm)

Grade
ABEC
Δdmp* Δds Ki Sdi Si ΔBs VBs
Upper Bottom Upper Bottom MAX MAX MAX Upper Bottom 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

Note 1: Grade 3P is usually defined by Δdm.
*1 Applicable to those with inner diameter of 10 mm or less.

Outer ring tolerance and tolerance value D≦30 mm

(Unit : μm)

Grade
ABEC
ΔDmp* ΔDs Ke Cs Se ΔCs VCs
Open shield/seal
Upper Bottom Upper Bottom Upper Bottom MAX MAX MAX Upper Bottom 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 2.5
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

Note 2: Grade 3P is usually specified by ΔDm.
*1 Applicable to those with outer diameter of 18 mm or less.

Excerpt from JIS B 1514-3

Allowable limit value of chamfer dimension for radial ball bearings

(Unit : mm)

rs min d rs max
Over Incl. Radial direction Axial direction
0.05
0.08
0.1
0.15
0.2
-
-
-
-
-
-
-
-
-
-
0.1
0.16
0.2
0.3
0.5
0.2
0.3
0.4
0.6
0.8
0.3 -
40
40
-
0.6
0.8
1
1
0.6 -
40
40
-
1
1.3
2
2
1 -
50
50
-
1.5
1.9
3
3

*1 The value in the radial direction applies to those with width of 2 mm or less.

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