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11

1 Bearing Life and Load Rating
1-1 Bearing life
Bearings are subjected to certain intensity of repeating stress on their track ring and rolling element
even during operation under proper loading, appropriate mounting and sufficient lubrication. The
stress may cause scaly damage formed on surface after certain time period due to its concentration atshallow vicinity under the surface. This phenomenon is called flaking (peeling-off of surface).
Phenomenon that causes bearing to be unusable due to flaking caused by repeating cyclic stressunder normal operating condition is called “life” of the bearing. Generally, bearing life is defined bytotal number of rotation of the bearing until flaking is generated on track surface. However,recognizing average life as criteria of bearing life is not appropriate for actual selection of bearing since
fatigue limit of material varies. It shall be practical to consider the life guaranteed to most bearings(basic rating life) as a criterion. Phenomenon that bearing becomes inoperative due to heat-seizure,
wear, fracture, scoring are regarded as “failure” caused by operating conditions and selection of
bearing so that they and the life should be considered as different phenomena.

Basic rating life time can be expressed as total rotation time with given rotation per minute by thefollowing formula.

L h = 10 6 L 10 / 60n = 500 f h p · · · · · · · · · · · · · (1.2)
f h = fn C r / P r · · · · · · · · · · · · · · · · · · · · · · · · · (1.3)
f n = ( 33.3 / n ) 1/p · · · · · · · · · · · · · · · · · · · · · (1.4)
Lh
n
fh
fn

: Basic rating life expressed in hour h: Rotation per minute rpm: Bearing life factor: Speed factor

Basic rating life scale
fn-nスケール

1-2 Basic rating life
Basic rating life of bearing shall be defined as a total number of rotation that 90% of the group of thesame bearings can run without causing flaking due to rolling fatigue when they are operated under
the same conditions.
In the case of rotation in certain constant speed, the basic rating life can be expressed in a totalrotation time as well.

1-3 Basic dynamic load rating
A given static radial load under which a bearing theoretically endures basic rating life of one million
rotations is referred to as a basic dynamic load rating.

A load that is virtually applied to the center of a bearing under which to obtain a life equivalent to thatwhen both radial load and axial load are subjected to the bearing at the same time is called the
dynamic equivalent radial load. In the case of needle bearing, its radial type is capable for loading
radial load only so that just a radial load will be applied.

1-5 Bearing life calculation formula
The following relationship is applied to basic rating life, basic dynamic load rating and dynamic
equivalent load of bearing.

L 10 = ( Cr / Pr ) p · · · · · · · · · · · · · · · · · · · · · · · (1.1)
L 10 : Basic rating life 10 rotation
6

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60000: Basic dynamic load rating N: Dynamic equivalent radial load N: Ball bearing p = 3, Roller bearing p = 10/3

fn-Lh scale

0.1
0.11

0.09

0.12

0.1

0.13

0.11

20000

0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19

10000

0.14
0.15
0.16
0.17
0.18
0.19

100000

5.5

5000

4.5

50000

4.5

4.0

2000

3.5

3.0
3.0
10000

0.25

0.35

0.3
0.35

0.4

0.4
0.45

0.5

500
400
300

0.5

200

0.6

0.6
100

0.7
0.8

50
40
30

0.9
1.0
1.1
1.2
1.3
1.4
1.5

20
10

0.45

0.7

1.9
1.8
1.7
1.6

3000

1.3

1000

1.2

0.9

1.0
1.1
1.2
1.3
1.4

0.8

1.2
1.1

1.1

0.9

1.5
1.4

1.3

1.0

1.8
1.7
1.6

2000

1.5

0.8

2.0
1.9

2.0

1.4

nn
fn fn
(rpm)
(rpm)
Ball玉軸受
bearing
Rollerbearing
ころ軸受
ffnn

2.5

2.5

5000
1000

4.0
3.5

0.2
3000

5.0

5.0

0.2

0.3

Dynamic equivalent radial load

12

0.08

0.25

1-4 Dynamic equivalent load

Cr
Pr
p

fn-Lhスケールfn-n scale

500
400
300

1.0
0.9
0.8

200

0.7

0.7

0.6

100
fh fh

fhfh
LLhh
(hour)(hour)
Ballbearing Roller
bearing
玉軸受
ころ軸受
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1-6 Operating conditions and bearing life factor of bearing

1-7 Corrected rating life

Operating machinery and demanded life
Bearings should be selected based on setting up demanded life in accordance with operatingmachinery and operating condition.
Demanded life is determined by endurance duration for operating machinery and reliable operating
periods.
Table-1 indicates demanded life that can be a typical reference.
Table-1 Operating condition and demanded life time factor (reference)
Operating conditions

Bearing life factor f h
~3

2~4

3~5

Agricultural machinery
Office equipment
Short duration or
Medical equip- Home air
Elevator
occasional operamentconditioning
Constructiontion, but necessity Measuringmachineryfor ensuring reliable instrument
operation
Crane
Small size mo- Machine tools
Factory general
tor
General gear
purpose motor
Long duration
Crusher
operation but not
systemWoodworking
full timemachinery
Passenger car
Air conditioner
Rolling maLarge size mochine
Continuous operaEscalator
tortion over eight
Compressor,
Conveyerhours a day
Centrifugal
pumpseparator
Operate 24 hours a
day and must be
non stop without
accident
Short duration or
occasional operation

4~7

6~

Home applianceElectrical tools

Formula for basic rating life described above is applied to bearings whose reliability is 90%, whosematerial is for general purpose bearing and are manufactured in general quality standard as well as
those operated under standard operating conditions. Corrected rating life should be calculated using
correction factor a 1, a 2 and a 3 in the case that the reliability is over 90% or that life needs to be obtained
for special bearing properties or for special operating conditions.

L na = a 1 a 2 a 3 L 10 · · · · · · · · · · · · · · · · · · · · · (1.5)
L na
a1
a2
a3

: Adjustment rating life 106 rotation: Reliability factor: Bearing special properties factor: Operating conditions factor

1-7-1 Reliability factor
Reliability factor a 1
Crane (sheave
wheel)

This is the bearing life corrected factor for reliability (100-n) % when probability of failure is n %. Valueof the reliability factor a 1 is shown in Table-2.
Table-2 Reliability factor a 1

Important gearsystemCalendar roller
for rubber andplastic
Printing machine
Mine hoist
Pulp,
Press machine papermaking
machineWater-worksystemPower generator system

Reliability (%)

Ln

a1

90

L 10

1

95

L5

0.62

96

L4

0.53

97

L3

0.44

98

L2

0.33

99

L1

0.21

1-7-2 Bearing special properties factor
Bearing special properties factor a 2
Bearing special properties factor a 2 is used for adjusting variation of properties concerning life in thecase that material type, quality or manufacturing process is special. This factor shall be a 2=1 for standard
material and manufacturing method. It can be a 2 > 1 when special modified material or manufacturingmethod is used due to improved quality of bearing material or progress of manufacturing technology.

14

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1-7-3 Operating conditions factor

1-8-2 Hardness factor

Operating conditions factor a 3
This is a factor to adjust impact of operating conditions of bearing, especially effect of lubrication tofatigue life.
Bearing life is essentially a fatigue phenomenon of surface layer which is subjected to repeating cyclicload. Therefore, this factor will be a 3=1 under ideal lubrication condition when rolling element and track
surface are completely isolated by oil film and surface failure can be ignored. Under poor lubrication
condition such as low lubricant viscosity or under significantly slow rotation speed of rolling element, it
would be a 3 < 1.

The raceway surface should be HRC58 to 64 in the case of using shaft or housing as raceway insteadof bearing inner ring or outer ring respectively. Basic dynamic load rating may be reduced in the casethe surface hardness is lower than HRC58. Basic dynamic load rating with consideration for surface
hardness is given by the following formula.

C 2 = f2 C r · · · · · · · · · · · · · · · · · · · · · · · · · · · (1.7)
C2
f2
Cr

On the contrary, it can be a 3 > 1 under especially excellent lubrication condition. Generally, the bearing
special properties factor a 2 can not be set to value exceeding 1 when a 3 < 1.

C 1 = f 1 C r · · · · · · · · · · · · · · · · · · · · · · · · · · · (1.6)
C1
f1: Temperature factor (Refer to Figure-1)

Cr: Basic dynamic load rating N: Basic dynamic load rating with consideration for temperature increase N: Basic dynamic load rating N

0.8
Hardness factor f2

While operating temperature of bearing is individually defined in accordance with material andstructure, bearing is capable to be used at temperatures higher than 150 °C by applying special treatment
for thermal resistance. However this will cause reduction of basic dynamic load rating as a result of
reduction of permissive contact stress. Basic dynamic load rating with consideration for temperature
increase is given by the following formula.

: Hardness factor (Refer to Figure-2)

1

1-8 Adjustment of Basic Dynamic Load Rating for temperature andhardness factors
1-8-1 Temperature factor: Basic dynamic load rating with consideration for hardness N

0.6
0.4
0.2
0

60

50
Hardness [HRC]40

Figure-21Temperature factor f1

1-9 Basic static load rating
Basic static load rating is specified as a static load which corresponds to contact stress indicated in thetable below at rolling element and the center of contact of track that are subjected to the maximum
load. Total permanent deformation of rolling element and track occurred by the contact stress may beapproximately 0.0001 times of diameter of the rolling element.

0.9
0.8

Type of bearing

Contact stress MPa

Roller bearing

4000

0.7
0.6
0.5

150

170

190
210
Temperature [℃]

230

250

Figure-1

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２ Bearing load

1-10 Static equivalent load

2-1 Load factor

A load that is virtually applied to the center of a bearing under which to obtain a contact stressequivalent to the maximum contact stress that occurs at contact surface between rolling element andtrack, when both radial load and axial load are subjected to the bearing at the same time, is called astatic equivalent load.
In the case of needle bearing, its radial type is capable for loading radial load only so that just a radialload will be applied.

P 0r = F r · · · · · · · · · · · · · · · · · · · · · · · · · · · · (1.8)
P 0r ： Static equivalent radial load N

Operation in actual machinery is subjected to a load larger than theoretical axial directional load due
to vibration and impact shock.
Actual load is given by calculation of load applied to axes system using load factor shown in Table-4.

K = f w · K c · · · · · · · · · · · · · · · · · · · · · · · · · · · (2.1)
K： Actual load applied to axes system N

K c ： Theoretical calculation value N
f w ： Load factor (Table-4)

1-11 Static safety factor

Table-4 Load factor

Although permissive limit of static equivalent load is typically regarded as basic static load rating, its
limit shall be set with consideration for safety since conditions required for bearings broadly vary. The
static safety factor fs is given by the following formula (1.9). Table-3 shows its typical values.

fS =
fS

C0r
· · · · · · · · · · · · · · · · · · · · · · · · · · · · (1.9)
P0r

C 0r ： Basic static load rating N

Air conditioner, measurement instruments, officeequipment
Gear box, vehicle, papermaking machine
Rolling machine, construction machinery, crusher

Smooth motion without any
impacts
With standard rotation

fs

With high rotation accuracy
With impact load

≧3With standard rotation accuracy≧ 1.5

With standard rotation accuracy
and low speed≧1

1.2~1.5
1.5~3

Load distribution to bearing
Axes system is assumed as a static beam supported by bearings in order to distribute load acting on
the axes system to the bearings. Table-5 shows calculation example of load distribution.
Table-5 Example of calculation of load distribution
ExamplesLoad calculationabc

1-12 Permissive rotation speed
Increasing bearing rotation speed may cause a rise in bearing temperature due to abrasion heatgenerated inside of the bearing, which results in failure with heat-seizure. A threshold rotation speed
up to which long duration of safe operation is enabled is referred to as a permissive rotation speed.
Permissive rotation speed varies depending on type, size and load of bearing, lubrication method andits radial clearance. It is an experimental value at which operation is enabled without causing heatgeneration exceeding certain limit.

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1 ~1.22-2 Load distribution

Table-3 Static safety factor

18

fw

ExamplesOperation with vibration andimpact shock： Safety factor

Operating conditions of bearing

Degree of load

a

b

F1 =

W1(b + c) + W2c
a+b+c

F2 =

W1a + W2(a + b)
a+b+c

F1 =

W1(a + b + c) + W2c
b+c

F2 =

W2b − W1ab+cc

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2-3 Load transmission
Bearing loads in belt or chain transmission

Bearing loads in gear transmission

The force acting on pulley or sprocket wheel when power is transmitted by a belt or chain is given by
the following formula.

T = 9550P/N · · · · · · · · · · · · · · · · · · · · · · · (2.2)

In the case of power transmission by gear, methods of calculation vary depending on the type of gear
since force acting on the gear is divided into radial load and axial load and their direction and ratio
vary depending on the type of gear. In the case of the simplest flat gear, direction of load is radial load
only and it is given by the following formula.

F t = 2000 ･ T/d · · · · · · · · · · · · · · · · · · · · · · (2.3)

T = 9550P/N · · · · · · · · · · · · · · · · · · · · · · · (2.5)

T： Torque acting on pulley or sprocket wheel N･m

Ft
P
N
d

： Effective force transmitted by belt or chain N： Transmitted power kW： Rotation per minute rpm： Effective diameter of pulley or sprocket wheel mm

Load F r acting on pulley shaft is given by multiplying effective transmitted force F t by belt factor f b
shown in Table-6 in the case of belt transmission.

F r = f b F t · · · · · · · · · · · · · · · · · · · · · · · · · · · (2.4)
Table-6 Belt factor
Type of beltfb

V belt

2 ~2.5

Flat belt (with tension pulley)

2.5~3

Flat belt (without tension pulley)

4 ~5

F t = 2000 ･ T/d · · · · · · · · · · · · · · · · · · · · · · (2.6)
F r = Ft ･ tan α · · · · · · · · · · · · · · · · · · · · · · · · (2.7)
Fc = F t 2 + F r 2 · · · · · · · · · · · · · · · · · · · · · · · · (2.8)
T： Torque acting on gear N･m

Ft： Force in tangent direction of gear N

Fr： Force in radial direction of gear N

F c ： Combine force acting perpendicular to gear N
P： Transmitted power kWN： Rotation per minute rpmd： Pitch circle diameter of drive gear ｍｍα： Pressure angle of gear

In the case of chain transmission, load acting on sprocket wheel shaft is given by the formula (2.4) assame as that of belt transmission using value between 1.2 and 1.5 as chain factor corresponding to f b.

Figure-3
Value that is given by multiplying theoretical load by gear factor f z in Table-7 shall be used as actualload since degree of vibration and impact shock affecting the theoretical load obtained by the formula
above varies depending on the type of gear and accuracy of gear surface finish.

F = f z F c · · · · · · · · · · · · · · · · · · · · · · · · · · · · (2.9)
Table-7 Gear factor
Type of gear
Precision gear
(Both of pitch error and geometric error is 0.02 mm or less)
Ordinary machined gear (Both of pitch error and geometricerror is between 0.02 mm and 0.1 mm)
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fz
1.05~1.1
1.1 ~1.3

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21

Average load
Average load F m which is converted so as to apply even life to each bearing may be used in the casethat load acting on bearing is unstable and changes in various cycle.

(3) Roughly linear load
Average load F m is approximately given by formula (2.12).

Fm =F min + 2F max· · · · · · · · · · · · · · · · · · · · · (2.12)
3(1) Fluctuating step load
Average load F m is given by formula (2.10) in the case that bearing load F 1, F 2, F 3… is applied withrotation speed and operation duration of n 1, n 2, n 3… and t 1, t 2, t 3… respectively.

F m = [ (F 110/3 ・n 1 t 1 + F 210/3 ・n 2 t 2 + … + F n10/3 ・n n t n ) /(n 1 t 1 + n 2 t 2 + … + n n t n )]3/10 · · · · · · · · · · · · · · · · · (2.10)

Figur-6 Load changing in linear increase

Figur-4 Load changing in stepping increment(2) Continuously fluctuating load
Average load is given by formula (2.11) in the case that the load can be expressed in function F (t ) oftime t with cycle t 0.

Fm =

l

t0

t0

∫ F(t) d0

10/3(4) Sinusoidal fluctuating load
Average load F m is approximately given by formula (2.13) and formula (2.14).

(a): F m=0.75F max · · · · · · · · · · · · · · · · · · · · (2.13)(b): F m=0.65F max · · · · · · · · · · · · · · · · · · · · (2.14)

3/10t· · · · · · · · · · · · · · · · · (2.11)

（ａ）

（ｂ）

Figur-7 Load changing in sinusoidal wave fluctuation
Figur-5 Load changing in function of time

22

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３ Bearing accuracy

3-1 Accuracy
Dimensional accuracy, geometrical accuracy and rotation accuracy of bearing are specified in ISO
standards and JIS B 1514 (Rolling bearings - Tolerances of bearings).
Accuracy class of needle bearing is specified by four classes from lowest class 0 to 6th, 5th and 4thclass in the highest. While high accuracy bearing in 5th or 4th class may be used in application for thecase high rotation accuracy is demanded or high speed rotation, class 0 is used in most of general
purpose application.
Table-8 Accuracy of inner ringdNominalbearing bore
diameter
(mm)

Δ dmp

Deviation of mean bore diameter in a single
plane
0

Over
2.51)
10
18
30
50
80
120
150
180
250

Unit: µm

654Incl. high low high low high low high low
10 0
-8
0
-7
0
-5
0
-4
18 0
-8
0
-7
0
-5
0
-4
30 0
-10
0
-8
0
-6
0
-5
50 0
-12
0
-10
0
-8
0
-6
80 0
-15
0
-12
0
-9
0
-7
120 0
-20
0
-15
0
-10
0
-8
150 0
-25
0
-18
0
-13
0
-10
180 0
-25
0
-18
0
-13
0
-10
250 0
-30
0
-22
0
-15
0
-12
315 0
-35
0
-25
0
-18 ̶ ̶Vdmp
Variation of
Vdsp
mean bore
Variation of bore diamdiameter in aeter in a single plane
single
plane
0
6
5
4
0 6 5 4
max.
max.
10
9
5
4
6 5 3 210954
6 5 3 213 10
65
8 6 3 2.515 13
86
9 8 4 319 15
9
7 11 9 5 3.5
25 19 108 15 11 5 431 23 13 10 19 14 7 531 23 13 10 19 14 7 538 28 15 12 23 17 8 644 31 18 ̶ 26 19 9 ̶

Kia
SdRadial runout of inner
Reference face runout
ring of assembled
with bore (Inner ring )bearing
0
10
10
13
15
20
25
30
30
40
50

6

5
max.
6
4
7
4
8
4
10
5
10
5
13
6
18
8
18
8
20
10
25
13

4

5

2.5
2.5
3
4
4
5
6
6
8

max.
7
3
7
3
8
4
8
4
8
5
9
5
10
6
10
6
11
7
13
̶

̶

4

Δ Bs

Deviation of a single
inner ring width
0, 6
5, 4
high low high low
0
-120
0
-40
0
-120
0
-80
0
-120
0
-120
0
-120
0
-120
0
-150
0
-150
0
-200
0
-200
0
-250
0
-250
0
-250
0
-250
0
-300
0
-300
0
-350
0
-350

d
VBs
NominalVariation of inner rings
bearing bore
width
diameter
(mm)
0
6
5
4
max.
Over Incl.
15
15
5 2.5
2.51)
10
20
20
5 2.5
10
18
20
20
5 2.5
18
30
20
20
5 3
30
50
25
25
6 4
50
80
25
25
7 4
80
120
30
30
8 5
120
150
30
30
8 5
150
180
30
30
10 6
180
250
35
35
13
̶
250
315

1）2.5 mm is included in this dimension group

Table-9 Accuracy of outer ring
VDmp
D
Δ
Variation
ofV
Nominal
Dmp
Dsp
mean
Deviation of mean outside diameter in a sinVariation of outside
bearing
outsidediametergle
plane
diameterinasingleplane
outsidein a single plane
diameter
(mm)
0
6
5
4
0
6
5
4
0 6 5 4
Over Incl. high low high low high low high low
max.
max.
2.52)
6 0
-8
0
-7
0
-5
0
-4 10
9
5
4
6 5 3 2
6
18 0
-8
0
-7
0
-5
0
-4 10
9
5
4
6 5 3 2
18
30 0
-9
0
-8
0
-6
0
-5 12 1065
7 6 3 2.5
30
50 0
-11
0
-9
0
-7
0
-6 14 1176
8 7 4 3
50
80 0
-13
0
-11
0
-9
0
-7 16 149
7 10 8 5 3.5
80
120 0
-15
0
-13
0
-10
0
-8 19 16 10
8 11 10 5 4
120
150 0
-18
0
-15
0
-11
0
-9 23 19 11
9 14 11 6 5
150
180 0
-25
0
-18
0
-13
0
-10 31 23 13 10 19 14 7 5
180
250 0
-30
0
-20
0
-15
0
-11 38 25 15 11 23 15 8 6
250
315 0
-35
0
-25
0
-18
0
-13 44 31 18 13 26 19 9 7SDKea
Variation of outside
Δ Cs
VCs
Radial runout of outersurface generatrix
Deviation of a single
Variation of outer ring
ring of assembled
inclination with faceouter ring width
widthbearing(outer ring)
0
6
5
4
5
4
0, 6, 5, 4
0
6
5
4
max.
max.
high
low
max.
15
8
5
3
8
4
5 2.5
15
8
5
3
8
4
5 2.5
15
9
6
4
8
4
5 2.5
Depending
20 10
7
5
8
4
5 2.5
on
Depending on tolerance
25 13
8
5
8
4
6 3
toleranceof Δ Bs for D of the sameof VBs for D
35 18
10
6
9
5
8 4
bearing.
of
the
same
40 20
11
7
10
5
8 5
bearing.
45 23
13
8
10
5
8 5
50 25
15
10
11
7
10 7
60 30
18
11
13
8
11 7

Unit: µm
D
Nominalbearing
outsidediameter(mm)
Over Incl.
6
2.52)
6
18
18
30
30
50
50
80
80
120
120
150
150
180
180
250
250
315

2）2.5 mm is included in this dimension group

24

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r s minTable-10 Permissive tolerance of chamfer
Unit: mmd
Radial direction
Axial direction
Nominal bearing bore diameterr s max
Over
Incl.

0.15

̶

̶

0.3

0.6

0.2

̶

̶

0.5

0.8

̶

40

40

̶

0.6
0.8

1
1

1
1.3

2
2

1.5
1.9

3
3

2
2.5

3.5
4

2.3
3

4
5

3
3.5
3.8

4.5
5
6

4
4.5

6.5
7

3.8
4.5
5

6
6
7

0.3

̶

40

40

̶

̶

50

50

̶

̶

120

120

̶

̶

120

120

̶

̶

80
220

0.6
1
1.1
1.5

80
220

2
2.1
2.5
3

̶

̶

280

280

̶

̶

100
280

100
280

̶

̶

280

280

̶

5
5.5

8
8

̶

̶

6.5

9

4

Table-11 Tolerance of minimum value of diameter of inscribed circle to roller Unit: µm
Dimension difference of Δ Fw min
Fw (mm)Variation of minimum value of diameter ofInscribed circle diameter
inscribed circle to roller
Over

Incl.

high

low

3

6

+18

+10

6

10

+22

+13

10

18

+27

+16

18

30

+33

+20

30

50

+41

+25

50

80

+49

+30

80

120

+58

+36

120

180

+68

+43

180

250

+79

+50

250

315

+88

+56

This means diameter of roller that achieves zero radial clearance in at least one radial direction in the case of using cylindrical roller
instead of bearing inner ring.

* Remark Although no particular shape is specified for chamfer surface, its outline in axial plane must be within virtual arc of r s minradius that is tangent to slope of inner ring and inner diameter face of bearing, or tangent to side of outer ring and bearing outer
diameter. (Reference diagram)

Side surface of inner ring orside surface of outer ringr

Bearing bore diameter surface orouter diameter surfacerr(Radial direction)rr(Axial direction)

26

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27

3-2 Measurement method
Measurement of single bore diameter
Table-12 Bearing bore diameter
Type and deﬁnition of accuracy
Arithmetic mean of maximum and minimum value of the single bore
diameters in a single radial plane.
dsp max + dsp min
dmp =
2

dmp
Mean bore diameter in asingle planedsp: Single inner diameter in a particular radial plane.
Difference between the mean bore diameter and nominal more diameter.
Δ dmp=dmp-d
d：Nominal bearing bore diameter.
Difference between maximum and minimum value of single bore diameter in single radial plane.
Vdsp=dsp max-dsp min
Difference between maximum and minimum value of the mean bore
diameter in a single plane in individual track ring basically with cylindricalinner diameter face.
Vdmp=dmp max-dmp min
Difference between single bore diameter and nominal bore diameter.
Δ ds=ds-d
ds：Distance between two parallel straight lines which are tangent tointersecting line of actual bore diameter face and radial plane.

Δ dmp

Deviation of mean bore
diameter in a single plane
Vdsp
Variation of single bore
diameter in a single plane
Vdmp
Variation of mean bore
diameter in a single planeΔ dsdeviation of single bore
diameter

Measurement of single outside diameter
Table-14 Bearing outer diameter
Type and deﬁnition of accuracy
Dmpmean outside diameterin a single plane

Arithmetic mean of maximum and minimum value of the single outside
diameters in a single radial plane.
Dmp =Dsp max + Dsp min
2

Dsp：Single outside diameter in a particular radial plane
Δ Dmp
Difference between the mean outside diameter in a single plane of
Deviation of mean out- cylindrical outside diameter face and nominal outside diameter.
side diameter in a single Δ Dmp=Dmp-D
D：Nominal bearing outside diameter.
plane
VDsp
Difference between maximum and minimum value of the mean outside
deviation of single out- diameter in a single radial plane.
side diameter
VDsp=Dsp max-Dsp min
VDmp
Difference between maximum and minimum value of the mean outside
Variation of mean out- diameter in a single plane in individual track ring with basically cylindricalside diameter in a single outer diameter face.
plane
VDmp=Dmp max-Dmp min
Difference between single outside diameter in basically cylindrical outΔ Ds
side diameter face and nominal outside diameter.
deviation of single bore Δ Ds=Ds-D
diameter
Ds：Distance between two parallel straight lines which are tangent tointersecting line of actual outer diameter face and radial plane.

Measurement range
Method of measurement of bearing bore diameter
Zero the gauge indicator to the appropriate size using gauge blocks or a master ring.
In several angular directions and in a single radial plane, measure and record the largest and thesmallest single bore diameters, d sp max and d sp min.
Repeat angular measurements and recordings in several radial planes to determine the largest andthe smallest single bore diameter of an individual ring, d s max and d s min.
Table-13 Measurement area limit
Unit: mmr s minaOver or less
0.6
r s max + 0.5
0.6
1.2 × r s max
28

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Measurement range
Method of measurement of bearing outer diameter
Zero the gauge indicator to the appropriate size using gauge blocks or a master ring.
In several angular directions and in a single radial plane, measure and record the largest and thesmallest single outside diameters, D sp max and D sp min.
Repeat and record measurements in several radial planes to determine the largest and the smallest
single outside diameter of an individual ring, D s max and D s min.
NOSE SEIKO CO.,LTD.

29

Measurement of single bore diameter of rolling element complement

Measurement of single inner ring width (or outer ring width)

Table-15 Measurement of single bore diameter of rolling element complement
Type and deﬁnition of accuracy
Fws
Distance between two parallel straight lines which are tangent to intersecting
Nominal bore diameterline of inscribed circle of rolling element complement and radial plane in radialof rolling element combearing without inner ring.
plement
Minimum nominal bore diameter of rolling element complement in radial bearing without inner ring.
Fws min
Minimum nominal bore
diameter of rolling ele- Remark Minimum nominal bore diameter of rolling element complement isment complement
diameter of cylinder whose radial clearance becomes zero in at least
one radial direction.

Table-17 Measurement of single inner ring width (or outer ring width)
Type and deﬁnition of accuracy
Δ Bs

Difference between single inner ring width and nominal inner ring width.
Deviation of single inner
Δ Bs=Bs-B
ring width
VBs
Difference between maximum and minimum value of the single bore
Variation of inner ring
diameter width in each inner ring.
width
VBs=Bsmax-Bs min
Δ Cs
Difference between single outer ring width and norminal outer ring
Deviation of single outer widthring width
Δ Cs=Cs-C
VCs
Difference between maximum and minimum value of the single outer
Variation of outer ring
ring width in each outer ring.
width
VCs=Cs max-Cs min

Measurement load

Master gauge
Measurement of single bore diameter of rolling element complement

Fasten the master gauge to a surface plate.
Position the bearing on the master gauge and apply the indicator in the radial direction to theapproximate middle of the width on the ring outside surface.
Measure the amount of movement of the outer ring in the radial direction by applying sufficient loadon the outer ring in the same radial direction as that of the indicator and in the opposite radial
direction.
Record indicator readings at the extreme radial positions of the outer ring. Rotate the bearing andrepeat the measurement in several different angular positions to determine the largest and thesmallest readings, F ws max and F ws min.
Measurement of single inner ring width (or outer ring width)
Table-16 Radial measurement load
MeasureFw
ment load
mm
N
Over
Incl.
min.
―
50
30
60
30
50
70
50
80
80
80
―

30

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Zero the gauge indicator to the appropriate height from the reference surface using gauge blocks or amaster gauge.
Support one face of the ring on three equally spaced fixed supports of equal height and provide two
suitable radial supports on the bore surface set at 90°to each other to center the ring.
Position the indicator against the other face of the ring opposite one fixed support.
Rotate the ring one revolution and measure and record the largest and the smallest single ring width,
B s max and B s min (C s max and C s min).

NOSE SEIKO CO.,LTD.

31

Measurement of perpendicularity of inner ring face with respect to the bore (Sd)Measurement of radial runout of inner ring (Kia)

Use a precision arbor having a taper of approximately 1:5000 on diameter.

Use a precision arbor having a taper of approximately 1:5000 on diameter.

Mount the bearing assembly on the tapered arbor and place the arbor between two centres so that it
can be accurately rotated.

Mount the bearing assembly on the tapered arbor and place the arbor between two centres so that it
can be accurately rotated.

Position the indicator against the reference face of the inner ring at a radial distance from the arboraxis of half the mean diameter of the face.

Position the indicator against the outside surface of the outer ring as close as possible to the middle ofthe outer ring raceway.

Take indicator readings while rotating the inner ring one revolution.

Hold the outer ring to prevent rotation but ensure its weight is supported by the rolling elements.
Take indicator readings while rotating the arbor one revolution.

Rotate the inner ring one revolution

Rotate the arbor one revolution
Mean diameter of inner ringdatum surface

Measurement of perpendicularity of inner ring face with respect to the bore

Measurement of perpendicularity of outer ring outside surface with respect to the face(SD)
Support the reference face of the outer ring on a surface plate leaving the inner ring, if an assembled
bearing, free. Locate the outer ring cylindrical outside surface against two supports set at 90°to eachother to centre the outer ring.
Position the indicator directly above one support. The indicator and the two supports are axiallylocated at the extremes of the measurement zone.
Take indicator readings while rotating the outer ring one revolution.

Measurement of radial runout of inner ring

Measurement of radial runout of outer ring (Kea)
Use a precision arbor having a taper of approximately 1:5000 on diameter.
Mount the bearing assembly on the tapered arbor and place the arbor between two centres so that it
can be accurately rotated.
Position the indicator against the outside surface of the outer ring as close as possible to the middle ofthe outer ring raceway.
Hold the inner ring stationary. Take indicator readings while rotating the outer ring one revolution.

Rotate the outer ring one revolution

Measurement of perpendicularity of outer ring outside
surface with respect to the face
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Measurement of radial runout of outer ring
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33

４ Internal clearance of bearing

4-2 Selection of radial internal clearance of bearing

4-1 Radial internal clearance of bearing
Radial internal clearance of bearing means a displacement of either inner ring or outer ring, which is
free side, when the specified measurement load is applied to it alternatively in radial direction whilelocking the opposite component in the condition before mounting the bearing on shaft or housing.
This measurement loads are quite small and they are specified in JIS B 1515:2006 (Rolling bearings Tolerances). Radial internal clearance of needle bearing with inner ring is specified in JIS B 1520:1995(radial internal clearance of bearing). Clearances shown in Table-18 are categorized in group C2, CN,
C3, C4, C5 starting from smaller clearance and group CN is applied to general application.
■ Radial internal clearance of bearing

Table-18 Internal clearance of radial bearing
Category
C2

Typically, larger radial internal clearance causes increase of vibration and smaller one results in heatgeneration or reduction of life due to excessive force between rolling element and track. Initial radial
internal clearance may be selected as slightly larger than zero clearance in consideration for theinternal clearance during operation. Bearing is designed to have suitable radial clearance by selecting
CN clearance for general application.

Reduction of radial internal clearance due to fits
When bearing is installed to shaft or housing, radial internal clearance reduces due to expansion or
shrinking of track with elastic deformation.

CN clearance Standard radial clearance
Radial clearance larger than standard clearance

Reduction of radial clearance due to temperature difference between inner and outer
ring

Table-19 Value of radial internal clearance of needle bearingｄUnit: µm

Clearance category

Nominal bearing bore diameter(mm)

Radial internal clearance of needle bearing in operation may generally becomes smaller than initialradial internal clearance. Temperature difference between inner and outer bearing during operationand fit cause this change. The radial internal clearance has a significant impact to life, vibration andheat generation of bearing.

Description
Radial clearance smaller than standard clearance

C3, C4, C5

Selection of clearance

C2

CN

C3

C4

Friction heat generated by rotation of bearing will be released to outside through shaft and/or
housing. In general application, radial internal clearance may be reduced as much as the difference ofamount of thermal expansion between inner and outer ring since outer ring becomes cooler thaninner ring due to larger heat release from housing than that from shaft.

C5

Over

Incl.

min.

max.

min.

max.

min.

max.

min.

max.

min.

max.

-

10

0

25

20

45

35

60

50

75

-

-

10

24

0

25

20

45

35

60

50

75

65

90

24

30

0

25

20

45

35

60

50

75

70

95

30

40

5

30

25

50

45

70

60

85

80

105

40

50

5

35

30

60

50

80

70

100

95

125

50

65

10

40

40

70

60

90

80

110

110

140

65

80

10

45

40

75

65

100

90

125

130

165

80

100

15

50

50

85

75

110

105

140

155

190

100

120

15

55

50

90

85

125

125

165

180

220

120

140

15

60

60

105

100

145

145

190

200

245

140

160

20

70

70

120

115

165

165

215

225

275

160

180

25

75

75

125

120

170

170

220

250

300

180

200

35

90

90

145

140

195

195

250

275

330

200

225

45

105

105

165

160

220

220

280

305

365

225

250

45

110

110

175

170

235

235

300

330

395

Remark Nominal number C2,C3,C4 are displayed as part code suffix for these bearings (excluding CN clearance). Example) NA 4903 C2

34

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35

５ Fits
Selection of fits

5-1 Purpose of fits
Purpose of “fits” for a bearing is to fixate a bearing with sufficient “interference” between inner ringand shaft or between outer ring and housing. Insufficient “fits” may cause harmful phenomena which
result in damaging bearing or shortening its life such as abnormal wear in fitting surface, abnormal
heat by abrasion powder, abnormal rotation and vibration due to slip of fitting surface. Therefore, it isimperative to select proper fits for application.

5-2 Selection of fits
Condition for selection of fits
Selection of bearing “fits” needs to consider following points. Properties and size of load in application,
condition of temperature, accuracy of rotation, material, finish, wall thickness of shaft and housing andeasiness of assembling/disassembling.
“Fits” as shown in Table-20 is generally determined based on properties of load and condition ofrotation.
Table-20 Properties of radial load and fits
Properties of bearing load

Fits
Inner ring Outer ring

Inner ring: rotation
Outer ring: stationary
Loading direction: constant

Load withrotating inner
ring
Load withstationary outerring

Tight fit

Loose fit

Inner ring: stationary
Outer ring: rotation
Loading direction: rotate together withouter ring

It is necessary to take condition of temperature and material of shaft and housing into considerationin addition to properties of load and rotation condition for selection of “fits” as mentioned above. Yet,
it is common practice to determine “fits” based on reference to experience and past record because ofdifficulty for recognizing whole conditions. Table-21 and Table-22 show “fits” for general application
and Table-23 shows “fits” for needle bearing without inner ring against shaft.
Table-21 Fits between needle bearing and housing hole
Conditions
Tolerance grade for housing
Standard and heavy load
J7
Load with stationary outer ring
Split housing with standard load
H7Light load
J7
Load in inconsistent direction
Standard load
K7
Heavy load and impact shock load
M7
Light load
M7
Load with rotating outer ringStandard load
N7
Heavy load and impact shock load
P7
Light load and high rotation accuracy
K6
Table-22 Fits between needle bearing with inner ring and shaft
Shaft diameter (mm)Conditions
Tolerance grade
Over
Incl.
̶
50
j5
Light load
50
100
k5
Load with rotating̶
50
k5
inner ring
50
150
m5･m6
Standard load
orLoad in inconsistent
150~
m6･n6
direction
~150
m6･n6
Heavy load and impact shock
load
150~
n6･p6
Mid to low speed, light load
g6
Load with stationary Mid to low speed, standard load
All dimension
h6
inner ringor heavy load
With precision rotation accuracyh5RemarkInner ring: stationary
Outer ring: rotation
Loading direction: constant

Load withrotating outerring
Load withstationary innerring

Tight fit

Tight fit

Tight fit

Inner ring: rotation
Outer ring: stationary
Loading direction: rotate together with
inner ring

Direction of load isdue toLoad in incon- inconsistentvaryingload
direction
sistent direction or including unbalanced load
36

Loose fit

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Inner ring: rotation or stationary
Outer ring: rotation or stationary
Loading direction: inconsistentLight load Pr ≦ 0.06Cr Standard load 0.06Cr ＜ Pr ≦ 0.12Cr Heavy load Pr ＞ 0.12Cr
Pr: Dynamic equivalent radial load Cr: Basic dynamic load rating

Table-23 Fits between needle bearing without inner ring and shaft
Radial internal clearance
Nominal diameterof inscribed circle Clearance smaller than
Clearance larger than CN
CN clearance
Fw (mm)CN clearance
clearance
Over
Incl.
Tolerance group grade for shaft
65
k5
h5
g6
65
80
k5
h5
f6
80
160
k5
g5
f6
160
180
k5
g5
e6
180
200
j5
g5
e6
200
250
j5
f6
e6
250
315
h5
f6
e6
Remark Tight fit with housing hole smaller than k7 shall be modified with smaller shaft size in considering diameter shrink of
inscribed circle of roller after assembly.
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37

5-3 Table for shaft and housing fits
Table-24 Tolerances for shafts
Nominalbearing bore
diameterand nominal
diameter ofshaft
d (mm)

Unit: µm
Tolerance grade for shaftb12Over Incl. high

c12

d6

e6

e7

f5

f6

g5

g6

Tolerance grade for shaft

h5

h6

h7

h8

h9

h10

h11

low high low high low high low high low high low high low high low high low high low high low high low high low high low high low high low

h12

js5

j5

js6

j6

j7

k5

k6

m5

m6

n5

n6

p6

Nominalbearing bore
diameterand nominal
diameter ofshaft
d (mm)

high low high low high low high low high low high low high low high low high low high low high low high low high low

Over

Incl.

—

3 -140 -240 -60 -160 -20 -26 -14 -20 -14 -24 -6 -10 -6 -12 -2 -6 -2 -8 0

-4 0

-6 0 -10 0 -14 0

-25 0

-40 0

-60

0

-100 +2

-2

+2

-2 +3

-3

+4

-2

+6

-4

+4

0

3

6 -140 -260 -70 -190 -30 -38 -20 -28 -20 -32 -10 -15 -10 -18 -4 -9 -4 -12 0-5 0-8 0 -12 0 -18 0

-30 0

-48 0

-75

0

-120 +2.5 -2.5 +3

-2 +4

-4

+6

-2

+8

-4

+6 +1

+6

0

+6

+2

+9 +1

+9

+8

+2

+8

+4 +10+4 +12 +6—

3+4 +12+4 +13+8 +16+8 +20 +12

3

6

6 10 -150 -300 -80 -230 -40 -49 -25 -34 -25 -40 -13 -19 -13 -22 -5 -11 -5 -14 0-6 0-9 0 -15 0 -22 0

-36 0

-58 0

-90

0

-150 +3-3+4-2 +4.5 -4.5 +7-2 +10-5+7 +1 +10 +1 +12+6 +15+6 +16 +10 +19 +10 +24 +15

610

10 18 -150 -330 -95 -275 -50 -61 -32 -43 -32 -50 -16 -24 -16 -27 -6 -14 -6 -17 0-8 0 -11 0 -18 0 -27 0-43 0-70 0 -1100-180 +4-4+5-3 +5.5 -5.5 +8-3 +12-6+9 +1 +12 +1 +15+7 +18+7 +20 +12 +23 +12 +29 +18

1018

18 30 -160 -370 -110-320 -65 -78 -40 -53 -40 -61 -20 -29 -20 -33 -7 -16 -7 -20 0-9 0 -13 0 -21 0 -33 0-52 0-84 0 -1300-210 +4.5 -4.5 +5-4 +6.5 -6.5 +9-4 +13-8 +11 +2 +15 +2 +17+8 +21+8 +24 +15 +28 +15 +35 +22

1830-80 -96 -50 -66 -50 -75 -25 -36 -25 -41 -9 -20 -9 -25 0 -11 0 -16 0 -25 0 -39 0-62 0 -100 0 -1600-250 +5.5 -5.5 +6-5 +8-5 +15 -10 +13 +2 +18 +2 +20+9 +25+9 +28 +17 +33 +17 +42 +26-100-119 -60 -79 -60 -90 -30 -43 -30 -49 -10 -23 -10 -29 0 -13 0 -19 0 -30 0 -46 0-74 0 -120 0 -1900-300 +6.5 -6.5 +6-7 +9.5 -9.5 +12-7 +18 -12 +15 +2 +21 +2 +24 +11 +30 +11 +33 +20 +39 +20 +51 +32-120-142 -72 -94 -72-107 -36 -51 -36 -58 -12 -27 -12 -34 0 -15 0 -22 0 -35 0 -54 0-87 0 -140 0 -2200-350 +7.5 -7.5 +6-9 +11 -11-9 +20 -15 +18 +3 +25 +3 +28 +13 +35 +13 +38 +23 +45 +23 +59 +37

140 160 -280 -680 -210-610 -145-170 -85-110 -85-125 -43 -61 -43 -68 -14 -32 -14 -39 0 -18 0 -25 0 -40 0 -63 0 -100 0 -160 0 -250

0-400 +930 40 -170 -420 -120-370
40 50 -180 -430 -130-380
50 65 -190 -490 -140-440
65 80 -200 -500 -150-450
80 100 -220 -570 -170-520
100 120 -240 -590 -180-530

-8

+11

+13

120 140 -260 -660 -200-600

30

40

40

50

50

65

65

80

80

100

100

120

120

140

+7 -11 +12.5-12.5 +14 -11 +22 -18 +21 +3 +28 +3 +33 +15 +40 +15 +45 +27 +52 +27 +68 +43 140160

160 180 -310 -710 -230-630

160

180

180 200 -340 -800 -240-700

180

200

+7 -13 +14.5-14.5 +16 -13 +25 -21 +24 +4 +33 +4 +37 +17 +46 +17 +51 +31 +60 +31 +79 +50 200

225

225 250 -420 -880 -280-740

225

250

250 280 -480 -1000 -300-820

250

280

280

315

200 225 -380 -840 -260-720 -170-199-100-129-100-146 -50 -70 -50 -79 -15 -35 -15 -44 0 -20 0 -29 0 -46 0 -72 0 -115 0 -185 0 -290

280 315 -540 -1060 -330-850-190-222-110-142-110-162 -56 -79 -56 -88 -17 -40 -17 -49 0 -23 0 -32 0 -52 0 -81 0 -130 0 -210 0 -3200-9-460 +10 -100-520 +11.5-11.5 +7 -16 +16 -16+16 -16 +26 -26 +27 +4 +36 +4 +43 +20 +52 +20 +57 +34 +66 +34 +88 +56

Unit: µm

Table-25 Tolerances for holes
Nominalbearing outer
diameter andnominaldiameter of
hole
D(mm)
Over Incl.

Housing tolerances and resulting ﬁts

B12

high

E7

low

E8

E9

F6

F7

G6

G7

H6

Housing tolerances and resulting ﬁts

H7

H8

H9

H10

H11

high low high low high low high low high low high low high low high low high low high low high low high low high low

JS6

J6

JS7

J7

K5

K6

K7

M6

M7

N6

N7

P6

P7

R7

S7

Nominalbearing outer
diameter andnominaldiameter ofhole
D (mm)

high low high low high low high low high low high low high low high low high low high low high low high low high low high low high low Over—3+240 +140 +24 +14 +28 +14 +39 +14 +12 +6 +16 +6 +8 +2 +12 +2 +6 0 +10 0 +14 0

+25 0

+40 0

+60 0

+3

-3

+2 -4 +5

-5

+4 -6

0

-4

-8 -2 -12

-4 -10-4 -14-6 -12-6 -16 -10 -20 -14 -24

—

3

3

6

+260 +140 +32 +20 +38 +20 +50 +20 +18 +10 +22 +10 +12 +4 +16 +4 +8 0 +12 0 +18 0

+30 0

+48 0

+75 0

+4

-4

+5 -3 +6

-6

+6 -6

0

-5 +2

-6 +3 -9 -1

-9

0 -12

-5 -13-4 -16-9 -17-8 -20 -11 -23 -15 -27

3

6

6 10

+300 +150 +40 +25 +47 +25 +61 +25 +22 +13 +28 +13 +14 +5 +20 +5 +9 0 +15 0 +22 0

+36 0

+58 0

+90 0

+4.5 -4.5 +5 -4 +7.5 -7.5 +8 -7 +1-5 +2-7 +5 -10 -3 -12

0 -15-7 -16-4 -19 -12 -21-9 -24 -13 -28 -17 -32

6

10

10 18

+330 +150 +50 +32 +59 +32 +75 +32 +27 +16 +34 +16 +17 +6 +24 +6 +11 0 +18 0 +27 0+43 0+70 0 +110 0+5.5 -5.5 +6 -5 +9-6 +2-9 +6 -12 -4 -15

0 -18-9 -20-5 -23 -15 -26 -11 -29 -16 -34 -21 -39

10

18

18 30

+370 +160 +61 +40 +73 +40 +92 +40 +33 +20 +41 +20 +20 +7 +28 +7 +13 0 +21 0 +33 0+52 0+84 0 +130 0+6.5 -6.5 +8 -5 +10.5 -10.5 +12 -9 +1

30 40+420 +170

0 -21 -11 -24-7 -28 -18 -31 -14 -35 -20 -41 -27 -48

18

30

30

40 50

+430 +180

40

40

50

50 65

+490 +190-30 -60 -42 -72

50

65

65 80

+500 +200

80 100+570 +220-32 -62 -48 -78

65

80-38 -73 -58 -93

80

100

100 120+590 +240-41 -76 -66 -101 100

120

120 140+660 +260-48 -88 -77 -117 120

140

140 160+680 +280 +125 +85+148 +85+185 +85 +68 +43 +83 +43 +39 +14 +54 +14 +25 0 +40 0 +63 0 +100 0 +160 0 +250 0

0 -40 -20 -45 -12 -52 -36 -61 -28 -68 -50 -90 -85 -125 140

160

160 180+710 +310-53 -93 -93 -133 160180

180 200+800 +340-60 -106 -105 -151 180

200

200 225+840 +380 +146+100+172+100+215+100 +79 +50 +96 +50 +44 +15 +61 +15 +29 0 +46 0 +72 0 +115 0 +185 0 +290 0

0 -46 -22 -51 -14 -60 -41 -70 -33 -79 -63 -109 -113 -159 200

225

225 250+880 +420-67 -113 -123 -169 225

250-74 -126 -138 -190 250

280-78 -130 -150 -202 280

315

250 280 +1000 +480
280 315 +1060 +540

38

-9 +10 -8 +2-6

0 -10 -2

-8 +2 -11 +6 -15 -4 -17+75 +50 +89 +50+112 +50 +41 +25 +50 +25 +25 +9 +34 +9 +16 0 +25 0 +39 0+62 0 +100 0 +160 0+8-9 +3 -13 +7 -18 -4 -20

0 -25 -12 -28-8 -33 -21 -37 -17 -42 -25 -50 -34 -59+90 +60+106 +60+134 +60 +49 +30 +60 +30 +29 +10 +40 +10 +19 0 +30 0 +46 0+74 0 +120 0 +190 0+9.5 -9.5 +13 -6 +15 -15 +18 -12 +3 -10 +4 -15 +9 -21 -5 -24

0 -30 -14 -33-9 -39 -26 -45 -21 -51+107 +72+126 +72+159 +72 +58 +36 +71 +36 +34 +12 +47 +12 +22 0 +35 0 +54 0+87 0 +140 0 +220 0+162+110+191+110+240+110 +88 +56 +108 +56 +49 +17 +69 +17 +32 0 +52 0 +81 0 +130 0 +210 0 +320 0

NOSE SEIKO CO.,LTD.

-8 +10 -6 +12.5 -12.5 +14 -11 +2

0

Incl.

+11 -11 +16 -6 +17.5 -17.5 +22 -13 +2 -13 +4 -18 +10 -25 -6 -28+12.5 -12.5 +18 -7 +20 -20 +26 -14 +3 -15 +4 -21 +12 -28 -8 -33+14.5 -14.5 +22 -7 +23 -23 +30 -16 +2 -18 +5 -24 +13 -33 -8 -37+16 -16 +25 -7 +26 -26 +36 -16 +3 -20 +5 -27 +16 -36 -9 -41

0 -35 -16 -38 -10 -45 -30 -52 -24 -59

0 -52 -25 -57 -14 -66 -47 -79 -36 -88

NOSE SEIKO CO.,LTD.

39

6 Design of shaft and housing
6-1 Accuracy of fitting surface

6-4 Skew of bearing

Correct design and manufacturing of shaft or housing to which needle bearing is assembled are vital foradequate bearing performance since the needle bearing has thinner track ring compared to other types ofrolling bearings. Table-26 shows dimension accuracy and geometric accuracy of “fitting” part of shaft andhousing in standard application condition, surface roughness and tolerance of runout of shoulder against
fitting surface. For values of tolerance class IT, please refer to Table-30 on page 42.
Table-26 Accuracy of shaft and housing (recommended)
Item

Shaft

HousingRoundness tolerance

IT3~IT4

IT4~IT5

Cylindricity tolerance

IT3~IT4

IT4~IT5

Shoulder runout tolerance

IT3

IT3~IT4

Roughness of fitting surface

0.8a

1.6a

Skew between inner ring and outer ring generated by deflection of shaft due to external force or
mounting error may result in reduction of life caused by abnormal wear or heat. While permissive
amount of skew varies depending on type of bearing, load and bearing internal clearance, it is recommended to be 1/2000 or less for general application.

6-5 Mounting dimension for bearing
Dimension of shaft and housing for mounting needle bearing (Figure-8) is shown in dimension table
for respective bearings.

6-2 Accuracy of track surface
Needle bearing can be directly attached to shaft or housing as track for compact bearing structure. In
this case, accuracy and roughness of track surface must be equivalent to that of bearing track surface
in order to ensure bearing life with high rotation accuracy. Since accuracy and roughness of shaft andhousing may affect life and the cause of abnormality of the bearing.
Table-27 shows specification for accuracy and roughness of track surface.
Table-27 Accuracy of track surface (recommended)
Item

Shaft

HousingRoundness tolerance

IT3

IT3

Cylindricity tolerance

IT3

IT3

Shoulder runout tolerance

IT3

IT3

Surface roughness

0.2a

6-3 Material and heat treatment of track surface
Surface hardness of shaft and housing must be HRC58 to 64 in order to obtain sufficient loading capacity
in the case of using them as direct track surface. Table-28 shows recommended heat treatment for theirmaterial.
Table-28 Material for track
Representative
Related stanType of steel
exampledardsHigh carbon-chromium
SUJ2
JIS G 4805
bearing steel
Chronium molybdemum
SCM415~435
JIS G 4053
steel

40

Carbon tool steel

SK85

JIS G 4401

Stainless steel

SUS440C

JIS G 4303

NOSE SEIKO CO.,LTD.

Figure-8 Mounting dimension

Fillet radius and height of shoulder for shaft and housing
Maximum permissive radius (ras max) of fillet radius for shaft and housing to which needle bearings areassembled corresponds to minimum permissive chamfer dimension (rs min) of the bearings.
Minimum value of shoulder diameter of the shaft (da) shall be nominal bore diameter (d) of bearing
plus its shoulder height (h) multiplied by 2. Maximum value of shoulder diameter of the housing (Da)shall be outer diameter (D) of bearing minus height of its shoulder multiplied by 2.
Table-29 Maximum permissive actual radius ofcorner R of shaft and housing ras max
rs minras max
Minimum permissive cham- Maximum permissive actual radius
fer dimensionof corner R of shaft and housing
0.1
0.1
0.15
0.15
0.2
0.2
0.3
0.3
0.4
0.4
0.6
0.6
1
1
1.1
1
1.5
1.5
2
2
2.1
2
2.5
2
Height of shoulder
and corner R
3
2.5
4
3
5
4
NOSE SEIKO CO.,LTD.

Unit: mm41

7 Lubrication
Table-30 Values of tolerance class IT for reference dimension
Reference dimensionmm

Unit: µm

Tolerance class

Over

Incl.

IT2

IT3

IT4

IT5

IT6

IT7

3

6

1.5

2.5

4

5

8

12

6

10

1.5

2.5

4

6

9

15

10

18

2

3

5

8

11

18

18

30

2.5

4

6

9

13

21

30

50

2.5

4

7

11

16

25

50

80

3

5

8

13

19

30

80

120

4

6

10

15

22

35

120

180

5

8

12

18

25

40

180

250

7

10

14

20

29

46

250

315

8

12

16

23

32

52

7-1 Purpose of lubrication
Purpose of bearing lubrication is to prevent its heat-seizure by mitigating friction and abrasion ofrolling surface and slipping surface. Followings are the detailed explanation.
(1) Mitigation of friction and abrasion
It prevents direct contact between track, rolling element and cage.
It also mitigates friction and abrasion as a result of slip on track surface.
(2) Removal of frictional heatLubricant removes abrasion heat inside of bearing or heat propagated from outside to prevent
excessive heat-up of the bearing.
(3) Extension of bearing life
Separating rolling element and track by oil film results in extension of bearing life.
(4) Prevention of rust
Oil film of lubricant mitigates oxidation inside and surface of bearing to prevent corrosion.
(5) Prevention of dust
Packed grease in the case of grease lubrication prevents invasion of foreign matter.
Efficient performance of these effects requires using lubrication method suitable for the application as
well as selection of proper lubricant, its adequate amount, prevention against invasion of external
foreign matter and optimal sealing structure in order to avoid leakage of the lubricant.

7-2 Comparison of grease and oil lubrication
Lubrication method
Lubrication method of bearing consists of grease lubrication and oil lubrication.
Grease lubrication is so popular for broad type of bearing because of its cost efficiency due to its
simple sealing structure and a long duration of operating period with single filling. However, its
disadvantage is larger flow resistance than oil lubrication in light of efficiency to large coolingcapability and high speed application.
Oil lubrication has advantage in large cooling capability and high speed application due to its goodflow characteristics. However, it demands design with consideration to sealing structure and leakage
prevention. The Table-31 compares the two lubrication methods as a guidance for lubrication method
selection.
Table-31 Comparison of grease and oil lubrication
Lubrication
methodGreaseOil

42

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Item
Replacement of lubricant△○

Lubrication performance○◎

Cooling efficiency

×○

Sealing structure○△

Power loss△○

Maintenance○△High speed operation

×○NOSE SEIKO CO.,LTD.

43

7-3 Grease lubrication
Filling amount of grease

Lubrication grease

Grease shall be packed up to a volume approximately one-third to one-half of internal space ofbearing or housing. Excessive grease may cause degraded lubrication performance due to leakage ofsoftened grease or oxidation as a result of increased temperature inside of bearing. This is criticalespecially in high speed operation.

Grease is a semi-solid lubricant consisting of a base oil (liquid lubrication agent) and a thickener, which
are combined on heating.

Figure-9 shows an example of grease replenishment plan from side way using a ring with grease hole.
Arranging grease holes evenly on circumference of the ring allows simultaneous entry of replenishedgrease into bearing for replacing old grease with new one. However, this design also allows standing
old grease in opposite side space, which needs to be removed periodically by removing the cover.

Table-32 Type and properties of grease (reference)
Calcium
Aluminum
Sodiumbase
Lithium grease
greasegreasegreaseCa + Nasoap
Li soap
Na soap
Al soap
Ca + Li
soap

Name

Thickener
Base oilNon-soap grease

Bentonite,urea,etc

Mineral oil Diester oil Silicon oil Mineral oil Mineral oil Mineral oil Mineral oil

Syntheticoil
250 ormore

Dropping
250 or170~190 170~190 200~250 150~180 150~180
70~90
point ℃
more
Working
temperature -25~+120 -50~+120 -50~+160 -20~+120 -20~+120 -10~+80 -10~+130 -50~+200℃

Mechanicalstability
Pressure
resistance
Water resistance
Figure-9 Grease lubrication

Good

Fair

Fair

Good~Fair

Good~Fair

Fair~Poor

Fair

Fair

Fair

Fair

Poor

Fair

Good~Fair

Fair

Fair

Fair

Fair

Fair

Fair

Fair~Poor Fair~Poor

Fair

Fair

Fair

Most
variousVersatilerollingbearing
Application grease

Superior Suitablefor highin lowtempera- and low
temperature,
turefriction
properties
Unsuitable forhigh load
due tolow oilfilm
strength

Vast application from
low to high temperature It includes types
showing superior
Suitable properties in resisfor bear- tance to high and low
ing being temperature, and to
Relatively Suitable subjected chemical by combinafor bear- to vibra- tion with base oil andgoodthickener
propertis ing being tionsubjected
to high
Versatile rolling beartempera- to vibraing grease
tion
ture
Subject to Superior
emulsify- in water
resistanceing byand memixing
chanicalwithstability
water

Superior
in viscosity

Remark Working temperature range is for general properties only and NOT for guarantee purpose.

1) Base oil
Mineral oil and mixed oil are used for base oil of grease.
Diester oil and silicone oil are used as mixed oil.
Lubrication performance depends on viscosity of the base oil, and generally, low viscosity base oil issuitable for low temperature environment and high speed application, and high viscosity is for hightemperature and high load application.
2) Thickener
Thickener is a material to keep grease in semi-solid state. Type of thickener has impact to maximum
working temperature, water resistance and mechanical stability.
Metal-soap base is popular for material of thickener. In addition, there are thickeners such as urea
base thickener with high heat resistance, and natrium soap-base thickener with poor water
resistance due to easiness to emulsifying by mixing with water.
44

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45

3) Consistency
Consistency refers to the “softness” of grease and it is used as a guideline for showing flow
characteristics. The larger the ASTM penetration No. is, the softer the grease is. Table-33 shows
typical relationship between consistency of grease and its operating conditions.
Table-33 Consistency of grease and its operating conditions
ASTM Penetration
NLGI Grade No.
Operating conditions(1/10mm)0355~3851

310~340

Centralized lubrication
Oscillating application2

265~295

General application

3

220~2504

175~205

General, high temperatureapplication
Grease with sealed
application4) Additives
Additives are material to improve performance of grease, which include antioxidants and extreme
pressure additives added as necessary. Condition to use grease for long period without any
replenishment requires added antioxidants to prevent oxidation.
Also, grease in operating conditions with heavy load or impact shock shall be selected from thosewith extreme pressure additives added.
5) Mixing different type greases
In principle, different brands of grease must not be mixed. Mixing different type grease is subject tonegative impact each other due to change of consistency and difference of additives.

Category

Brand

GeneralpurposeAlvania
Grease S1
Alvania
Grease S2
Alvania
Grease S3
Wide working Fomblin
temperature RT-15
Fomblin
Y-VAC1
Fomblin
Y-VAC2
Fomblin
Y-VAC3
Low
Multemp PS
temperature No.2

Other

Table-34 Brand of lubricant grease (reference)
Drop- Working
Manufac- Thickener
Consisping temperor soapturer
tency
point
ature ℃
base℃
Showa Shell Lithium
Sekiyusoap
Showa Shell Lithium
Sekiyusoap
Showa Shell Lithium
Sekiyusoap
SolvayPTFE
SolexisSolvayPTFE
SolexisSolvayPTFE
SolexisSolvayPTFE
Solexis
KYODO
Lithium
YUSHI
soap

180

-35~120 General purpose

283

181

-25~120 General purpose

242

182

-20~135 General purpose

NO.2-20~250 High temperature

NO.3

300 ormore
300 ormore
300 ormore
300 or
more

NO.2

190

-50~130 Low temperature

NO.1
NO.2

-20~250 High vacuum (soft)
vacuum-20~250 High(normal)-20~250 High vacuum (rigid)

Superior in abrasion resistance,
resistance,-40~188 loadwater resistanceand chemical resistanceLoad resistance, oil
solvent-65~250 resistance,
resistance, chemical resistance

OIL CENTER PTFERESEARCH

295

198

HP300

Dow
Corning

PTFE

280

-

BARRIERTA
SUPER IS/V
BARRIERT IEL/VNOKKLUBERNOKKLUBER

PTFE

No.2

-

-35~260 High vacuum

PTFE

No.2

-

-65~200 High vacuum
Superior in heat
resistance, load-50~150 resistance, water
resistance and highspeedtemperature-60~300 Highstability
temperature-70~200 Highstability
temperature,-23~180 Highhigh load
Superior in water
resistance, oxida-30~120 tion stability andmechanical stability

ISO FLEXTOPAS NB 52NOKKLUBER

Barium soap

No.2

240 ormore

DEMNUM
L-200
DEMNUM
L-65

DAIKIN

PTFE

280

-

DAIKIN

PTFE

280

-

G1/3Grease

The Orelube Non-soap
Corporation grease

No.2

-

Shell Cassida
Grease RLS2

Showa Shell Aluminium
Sekiyucomplex

No.2

240 or
more

No.2

-

pressure,-42~232 Extreme
high temperature

256

Heat stability, low
shear-50~204 volatility,
stability, high vacuum

Castrol Micro- Castrol
cote 296

NOSE SEIKO CO.,LTD.

323

LOR#101

Super Lube
item number Henkel
82329

46

Remark

PTFE

PTFE

No.2

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47

7-4 Oil lubrication
Oil lubrication is more suitable than grease for high speed rotation with superior cooling efficiency. It
is suitable for application that requests emission of heat to outside that are generated in bearing oradded to the bearing.
1) Oil bath lubrication
Oil bath lubrication is the most popular method used in medium to low speed application. Amountof oil needs to be properly controlled with oil gauge. Oil drips through an oiler become an oil fog by
the wind pressure generated by rotating objects such as shafts, nuts, and etc. Then, it fills up the
housing and lubricate all the required parts. Recommended oil level is the center of the lowest
needle roller of a bearing. Housing design with less variation of oil level is preferred.

4) Oil circulating lubrication
Oil circulating lubrication is widely used in application whose purpose is in cost efficiency for
automatic lubrication with large number of lubrication spots, or is in cooling bearing. Thislubrication method enables cooling or maintaining cleanliness of lubricant with oil cooler and filters
installed in oil circulation system. As shown in Figure-11, to make sure that lubrication oil is drained
off entirely, it is important to have as much large outlet port as practical or forced outlet, setting inlet
and outlet port of lubrication oil to opposite side each other to bearing.

2) Oil drop lubrication
Oil drop lubrication is broadly used in application with high speed and medium load due to its
better cooling efficiency. Oil dripping through oiler in this method removes friction heat in amethod to lubricate with oil fog filling inside of housing by hitting rotating objects such as shafts
and nuts. While amount of oil varies with type of bearing and speed, in general, amount should be acouple of drops per minute.

Figure-11 Circulating lubrication

Lubrication oil
Highly refined mineral oil such as spindle oil, machine oil or turbine oil, or mixed oil are used as
lubrication oil for bearing. Additives such as antioxidants, extreme pressure additives or depurant are
selectively used as necessary in accordance with application.
It is important to select oil with proper viscosity for operation temperature. Too low viscosity causes
insufficient formation of oil film which results in abrasion or heat-seizure. Too high viscosity causes
heat generation or loss of power due to viscosity resistance. In general, oil with higher viscosity is used
for higher load and lower viscosity for higher speeds.

Figure-10 Oil drop lubrication
3) Oil splash lubrication
Oil splash lubrication is a method to splash oil with rotation of gear or disc. Unlike oil bathlubrication, it is applicable for relatively higher speed without having bearing directly soak in oil.

48

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49

８ Bearing handling

8-1 Precaution
Bearings are an extremely precise mechanical components. Great care should be exercised for its
handling.
1) Keep bearings and surroundings clean
Foreign matters invaded inside of bearings such as dust and dirt have harmful effect in rotation oroperation life on the bearings. Take extra precaution to maintain cleanliness of bearing, surrounding
components, work tools, lubricants, lubrications oil and working environment.
2) Handle bearings carefully
Shocks caused by falling bearing or other shocks inducing events may result in damage or
impressions on track or rolling elements. They can be a cause of failure. Therefore, bearings should
be handled carefully.

Mounting method
1) Press fitting
In case of mounting bearings from small to medium sizes which do not require large forces , press
fitting in room temperature is commonly used. In this case, use pressing fixture as shown in
Figure-12 to apply force evenly at side of bearing and press it in carefully. Applying high viscosity oil
on fitting surface during work may reduce friction on the surface.
Press

3) Use proper tools
Make sure work tools are used properly for bearing type for assembling and disassembling.
4) Pay attention to rust
Although bearings are applied with anti-rust oil, handling with bare hands may cause formation ofrust due to perspiration from hands. Great care should be exercised for handling bearings. Also,using rubber gloves or applying mineral oil to bare hands are recommended when handling.

8-2 Mounting
Preparation
Bearings should be mounted in clean and dry circumstance. Dirt on mounting tools should be
removed prior to mounting work, then verify that dimension accuracy, shaft and housing roughness
and geometric accuracy are within designed tolerance.
Packing of bearings should only be opened just before start mounting. Fill lubrication grease withoutwashing bearing in the case of grease lubrication. Washing is generally not required for oil lubrication
as well. It is still recommended to wash out thoroughly oil and grease when application demands highaccuracy or lubricating performance is degraded by mixed lubricant and anti-rust agents.

50

NOSE SEIKO CO.,LTD.

Figure-12 Press fitting of
Inner ring2) Shrink fitting
Shrink fitting is broadly used for tighter interference or mounting large size bearing. The housing forouter ring and inner ring are heated respectively with low corrosivity pure mineral oil so that theirinner diameter are expanded for mounting outer ring or onto the shaft. Heating temperature must
not exceed 120°C. During mounting, inner ring may expand toward shaft and needs to be pressedagainst shoulder until complete of cool down. This is to avoid gap between the inner ring and theshoulder.

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51

8-3 Operation inspection
Operation inspection needs to be performed in order to confirm that bearings is properly mounted.
Power operation at given speed without operation inspection may result in damage of bearings orheat-seizure due to lubrication failure in the case that mounting is insufficient. Shaft or housing should
be rotated by hand after bearing mounting to confirm if there is no abnormality followed by check (orinspection) in gradually increasing speed from no load, low speed operation with power up to loaded
operation.
Followings are typical abnormal items and major causes that can be checked in the operation
inspection.

Disassembling inner ring
Inner rings can be removed easily by press (Figure-14). Dedicated removal tool (Figure-15) designed inaccordance with dimension of the bearing is in use as well.

Press1) Inspection by hand
• Rotation torque fluctuation ････ Insufficient mounting• Abnormal noise ･･････････････ Impression, damage, invasion of dirt or foreign matters on track
surface• Excessive torque ･･････････････ Insufficient clearance2) Inspection by actual operation• Abnormal noise, vibration ･････ Impression, excessive clearance, invasion of dirt or foreign
matters on track surface• Abnormal temperature ････････ Insufficient lubrication, insufficient mounting, insufficient
clearance

8-4 Removing
Bearing may be removed for periodical machine maintenance or repair. Bearing and othercomponents should be carefully disassembled in the same manner as mounting in the case of reusing disassembled bearing or researching malfunction condition.
Bearings should be carried out in an appropriate manner in accordance with type of bearing andcondition of fits. Structure design should take disassembling work into consideration at planning stageof construction around the bearing since it would be difficult to disassemble especially the tight fit
bearing.

Removing outer ring

Figure-14 Disassembling inner ring 1

Figure-15 Disassembling inner ring 2

8-5 Maintenance and inspection
Periodical maintenance and inspection are essential for maximizing performance and prolonged
usage of bearing as well as early discovery of abnormality of the bearings. Inspection items of bearings
under operation include temperature, operation sound, vibration of bearings and condition of
lubricant, whose observation enables judging timing of lubricant replenishment and replacement ofcomponents.

Installing bolts at several locations of the circumference of housing and tightening-up the screws
evenly will allow easier removal of tight fits assembled outer ring as shown in Figure-13.
Bolt fordisassembling

Figure-13 Disassembling outer ring52

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53

54

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55

Machined type needle roller bearings（NA、NK、NA..UU）

Type and Part CodeApplicable axis
diameterType

ф 7 ~ ф 175

RNA48,49,59,69

ф 5 ~ ф 110NK

ф 5 ~ ф 100

Machined type needle roller bearings
Light load type
Outer ring with ribs
With inner ring
Without seal
(There are no oil holes and oil grooves if the bore
diameter is 8mm or less)ф 14 ~ ф 58

Machined type needle roller bearings
Outer ring with ribs
Without inner ringWith seals*Double rows: RNA69 (Fw ≧ф 42)

ф 10 ~ ф 50

Machined type needle roller bearings
Outer ring with ribs
With inner ringWith seals*Double rows: NA69 (shaft dia. ≧ф 35)

RNA49,69..UU

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NOSE SEIKO CO.,LTD.

Machined type needle roller bearings
Light load type
Outer ring with ribs
Without inner ring
Without seal
(There are no oil holes and oil grooves if the roller set
bore diameter (Fw) is 10 mm or less)ф 5 ~ ф 160

NKI

NA49,69..UU

Machined type needle roller bearings
Outer ring with ribs
Without inner ring
Without seal
*Double rows: RNA69 (Fw ≧ф 37)

Machined type needle roller bearings
Outer ring with ribs
With inner ring
Without seal
*Double rows: NA69 (shaft dia. ≧ф 32)

NA48,49,59,69

Part CodeFeatureRNA

Type ofbearing

49

10

P6

Dimension series
Accuracy class (Class 6) (Standard: No symbol, Class 0)
Bore diameter numberNK

40 ／ 20P6Type of
Outer ring width
bearing Inscribed circle diameter
Accuracy class (Class 6) (Standard: No symbol, Class 0)

NA

49

10

C3

P6

Accuracy class (Class 6) (Standard: No symbol, Class 0)
Type of Dimension series
Clearance symbol (C3 clearance) (Standard: No symbol, CN clearance)
bearing
Bore diameter number
NKI

Type ofbearingRNA

35 ／ 20

C3

Bore diameter
Outer ring width
49

10

P6

Accuracy class (Class 6) (Standard: No symbol, Class 0)
Clearance symbol (C3 clearance) (Standard: No symbol, CN clearance)

UU

P6

Accuracy class (Class 6) (Standard: No symbol, Class 0)
UU：With seals
Type of Dimension series
bearing
Bore diameter number
NA

49

10

UU

C3

P6
Accuracy class (Class 6)(Standard: No symbol, Class 0)

UU：With seals
Type of Dimension series
bearing
Bore diameter number Clearance symbol (C3 clearance) (Standard: No symbol, CN clearance)

NOSE SEIKO CO.,LTD.

57

Structure and Features

With seal
NA49UU and NA69UU have seals embedded in both ends. The synthetic rubber seals help to prevent
lubricant leakage and the infiltration of dust and other contaminants from outside.

Machined type needle roller bearings offer high stiffness and bearing accuracy and are of a structure
whereby the cage and needle rollers are mounted on a machined outer ring. They can also be used inlight metal housing due to the high stiffness of the outer ring.
Moreover, due to relatively small needle roller diameter and low cross-sectional height, large radialloads can be supported in a small envelope. This enables machines to be compact and light weight
design.

Without inner ring

Without inner ring
The shaft is directly used as the track surface of the machined type needle roller bearing. If using theshaft directly as a track surface, please refer to 6-2 Accuracy of track surface and 6-3 Material and heat
treatment of track surface.

Outer ring

Outer ring

Needle roller

Needle roller

Cage

Cage

Outer ring
Needle roller

Outer ring
Needle roller

Cage

Cage

Inner ring

Inner ring

Without seal

There are machined type needle roller bearings with and without inner rings. A shaft can be useddirectly as a track surface.

With inner ring

RNA,NK(single row)

With inner ring

Outer ring

Outer ring

Outer ring

Needle roller

Needle roller

Needle roller

Needle roller

Seal

Seal

Seal

Seal

Cage

Cage

Cage
Inner ring

Cage
Inner ring

RNA...UU(single row)

58

NOSE SEIKO CO.,LTD.

NA(double row)

Outer ringWith seal

If the shaft surface cannot achieve the specified hardness, accuracy and roughness, the type with an
inner ring is used. The inner ring has been tempered and polished so it is of the hardness, accuracy
and roughness required for the track and can be used as is.

NA,NKI(single row)RNA
(double row)

RNA...UU(double row)

NA...UU(single row)

NA...UU(double row)

NOSE SEIKO CO.,LTD.

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NOSE SEIKO CO.,LTD.

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93

Machined type needle roller bearings - Separable type (NAF)

Type and Part CodeApplicable axis
diameterType

FeaturePart CodeRNAFф 5 ~ ф 100

Machined type needle roller bearings
Outer ring with no rib
Without inner ringType ofbearing

RNAF(W)NAF
ф 6 ~ ф 90

Machined type needle roller bearings
Outer ring with no rib
With inner ringType ofbearing

NAF(W)

W

30

42

32

P6

Outer diameter
Width
Inscribed circle diameterNo symbol: Single row W: Double row
W

25

42

32

Classification symbol (Class 6)(Standard class 0 No symbol)
C3

P6

Classification symbol (Class 6)
Outer diameter(Standard class 0 No symbol)
Bore diameter
Width
No symbol: Single row W: Double row Clearance symbol (C3 clearance) (Standard: No symbol, CN clearance)

These are semi-standard products, so please contact JNS for any enquiries.

Structure and Features
A metric bearing which features a stiff machined outer ring and a cage with either a single or a double
row of needle rollers. This bearing has no ribs on the inside of the outer ring therefore the cage withneedle rollers can be easily separated from the outer and inner rings.
Because these bearing can be individually mounted on equipment, assembly is sometimes easier. The
cage with needle rollers is not constrained by ribs therefore the configuration must be one whichconstrains the movement of these parts.
Also, this type of bearing is not available with a seal.
On the single row standard type, there are no oil grooves and oil holes for lubrication on the outer
ring, and no oil holes on the inner ring.
On the double row standard type, there are oil grooves and oil holes for lubrication on the outer ring,
but no oil holes on the inner ring.
Without Inner ring
Outer ring
Needle roller

With Inner ring

Outer ring
Needle roller

Cage

Outer ring
Needle roller

94

RNAFW
(double row)
NOSE SEIKO CO.,LTD.

Cage

Cage

Cage

Inner ring

RNAF
(single row)

Outer ring
Needle roller

NAF(single row)

Inner ring

NAFW
(double row)
NOSE SEIKO CO.,LTD.

95

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NOSE SEIKO CO.,LTD.

NOSE SEIKO CO.,LTD.

107

Combined needle roller bearings (NKX..(Z), NKXI..(Z))

Type and Part CodeApplicable axis
diameterTypeф 10 ~ ф 70

NKX..(Z)ф 7 ~ ф 60

NKXI..(Z)FeaturePart Code
NKX

Machined type combined bearing
Radial bearing: needle bearing
Thrust bearing: ball bearing
Outer ring with ribs
Without inner ringType ofbearing30

Inscribed circle diameter Z: With dust coverNo symbol: Without dust cover

NKXI

Machined type combined bearing
Radial bearing: needle bearing
Thrust bearing: ball bearing
Outer ring with ribs
With inner ring

25

Type ofbearingMoreover, the combined needle bearing with dust cover keep thrust bearing intact with needle roller
bearing allowing easier handling. Splattering caused by centrifugal force within the thrust bearing canalso be prevented while greasing.

Cr

Needle roller

NOSE SEIKO CO.,LTD.

Needle roller
Cage

Inner ring

Ball

Ball

Cage

Cage

Structure of type NKX

Structure of type NKXI

Outer ring

Outer ring

Dust cover

Needle roller

Track ring forthrust bearing

Needle roller
Cage

With dust cover

Cage

Inner ring

Ball

Ball

Cage

Cage

Structure of type NKX..Z
108

Outer ring
Track ring forthrust bearing

Cage

Ca： Axial load
Cr ： Radial load

NKX
Combined needle bearing

With inner ring

Outer ring

Track ring forthrust bearing

Dust cover
Track ring forthrust bearing

RNA, NK
Needle bearing

Clearance symbol (C3 clearance)(Standard: No symbol, CN clearance)
Z: With dust coverNo symbol: Without dust cover

Without dust coverWith such property and tightly packed feature the combined needle roller bearings, it allowed a morecompact equipment design.

Cr

C3

Without inner ring

Combined needle roller bearings are made from the combination of radial needle bearings and thrustball bearings which support radial load and axial load respectively at the same time.

Ca

Z

Bore diameter

Structure and Features

Ca

Z

Structure of type NKXI..ZNOSE SEIKO CO.,LTD.

109

Accuracy standard

Radial internal clearance

Please refer to page 24 regarding accuracies for the radial section of combined needle bearings. Table-1
indicates thrust section accuracies.
Table-1 Thrust section accuracies
Inner ring
Outer ring

V dsp
Variation of
Deviation ofboremean bore
diameter indiameter in aa single
single plane
plane
Δ dmp

Part code

high

low

Δ Dmp

Deviation ofmean outer
diameter in asingle plane

Unit: µm
Inner ring/Outer ring
Si/Se
Variation of track
thickness

V Dsp
Variationof outerdiameterin a single Class 0 Class 6 Class 5
plane

max.

high

low

max.

max.

NKX10 to 15(Z)NKXI7 to 12(Z)

0

-8

6

0

-11

8

10

5

3

NKX17 to 30(Z)NKXI14 to 25(Z)

0

-10

8

0

-13

10

10

5

3

NKX35 to 50(Z)NKXI30 to 45(Z)

0

-12

9

0

-16

12

10

6

3

NKX60 to 70(Z)NKXI50 to 60(Z)

0

-15

11

0

-19

14

10

7

4

Table -3 indicates the radial internal
clearances of combined needle bearings
with inner rings (NKXI).

Fits
Table-4 indicates the recommended fits
between the combined needle bearing
and shaft and housing.

Table-3 Radial internal clearances Unit: µm
Radial internal clearance
Part codemin.
max.
NKXI 7 to 25
20
45
NKXI 30 to 40
25
50
NKXI 45 to 50
30
60
NKXI 60
40
70
NKXI 70
40
75
Table-4 Recommended fits
Unit: µm
Shaft tolerance
Housing tolerWithout Inner
ance
With Inner ring
ring
h5 k5
k5
K6, M6

Lubrication
Please refer to page 43 - 7 Lubrication regarding lubrication for the radial and thrust sections ofcombined needle bearings. For both the time with a dust cover and without, grease is pre-packed into
the thrust section before factory dispatch.

Rating life
Please calculate rating life for radial needle bearings and thrust ball bearings respectively using theformula provided on page 12 - 1 Bearing Life and Load Rating. Assume that the radial needle bearing
supports the radial element of load while the thrust ball bearing supports the thrust element. The
overall rating life is then calculated using the respective calculation results in the below formula.

Table-2 indicates the accuracies of the assembled bearings.
Table-2 Assembled bearing accuracy

Unit: mm

d

D

C

C1

E7
(Fitting accuracy)h5(Fitting accuracy)

MAX. 0
MIN, -0.25

MAX. 0
MIN, -0.2

 1 3/2  1 3/2  −2/3+ 
L =  · · · · · · · · · · · · · （0.0）

L
L




a
r


L ： Basic rating life of combined needle bearings is 106 rotation
L r ： Basic rating life of radial needle bearings is 106 rotation
L a ： Basic rating life of thrust ball bearings is 106 rotation

C

C

Mounting

C1

C1

106 REV.
106 REV.
106 REV.

φD

φd

φd

φD

The below is an example of combined needle bearing mounting. The thrust section housing and its
clearance must be made 0.5 mm or greater than the outer diameter of the outer ring ribs (NKX(I)) andthe outer diameter of the dust cover (NKX(I)..Z).
Housing
Shaft

NKX

110

NOSE SEIKO CO.,LTD.

NKX..ZNOSE SEIKO CO.,LTD.

111

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NOSE SEIKO CO.,LTD.

117

Inner ring (IR, IRZ)

Type and Part CodeType

Applicable axis
diameterф 5 ~ ф 160

FeaturePart Code
IR

25

30

17

Type of bearing

Bore
diameterOuter
diameter

Width

IRZ

25

30

18

Type of bearing

Bore
diameterOuter
diameter

Width

Inner ring (without oil hole)IRф 10 ~ ф 50

Inner ring (with oil hole)

IRZ

Structure and Features
For needle bearings, the shaft is normally subjected to heat treatment and is given a grinding finish
before being used as a track surface, however, if the specified hardness and roughness cannot be
achieved, inner rings are used.
Inner rings, after being subjected to heat treatment, are given a high accuracy grinding finish. The
endfaces are chamfered to allow easy insertion into the bearing and to prevent damage to the seal.
Depending on the conditions of use, there are inner rings with oil holes or without oil holes available
to select from.
It is preferable to use wide inner rings in cases where there is large shaft travel in the axial direction ora seal is used on the outside of the bearing.
Inner rings can also be used as bushes.

IR
IR (without oil hole)118

NOSE SEIKO CO.,LTD.

IRZ
IRZ (with oil hole)

NOSE SEIKO CO.,LTD.

119