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Selection of Bearing Type

Bearing Material

Rings(cups & cones) & Rolling elements
SFT bearing rings(cups & cones), balls & rollers are made of GCr15 high carbon chromium bearing steel
This steel No. is equal to the AISI 52100(U.S.A.), DIN 100Cr6(Germany), JIS SUJ2(Japan) etc.

Chemical composition of GCr15 steel:

Steel No.

Chemical composition %

GCr 15

C

Si

Mn

P

S

Cr

Mo

Cu

Ni

0.95-1.05

0.15-0.35

0.25-0.45

≤0.027

≤0.02

1.40-1.65

-

≤0.25

≤0.30


Contrast of steel no. in different countries

Country

China

ISO

U.S.A.

Japan

Germany

France

Sweden

Standard

GB

AISI

JIS

DIN

NF

Steel No.

GCr15

683/XVLL1

52100

SUJ2

100Cr6

100C6

SKF3


Hardness
Hardness of bearing rings(cups & cones) & rolling elements is HRC60
HRC65.

Retainers
SFT standard bearing retainers are made from cold rolled carbon steel. However, in cases of heavy duty, corrosive environment,misalignment and high speed operation, brass, stainless steel, nylon or phenolic resins will be used upon request.

Seals & Shields
SFT shields also employ carbon steel as standard.
Buna Nitrile is the standard and mostly common used material for SFT seals. Also, in order to meet the requirements of high temperature operation and compatibility with grease, a variety of other sealing materials are also applied to the seals.

Lubrication
Standard grease and oil are applied to SFT bearing products
SFT can also use special pointed brand grease or oil upon request

Tolerance

SFT bearing tolerance standard accords with Chinese national standard GB/T307(equal to ISO492)
The following are the contrast tables of Chinese national standard with the foreign standards.

Contrast of tolerance class for radial bearings in different countries(except tapered roller bearing)

Country

Standard

Tolerance class

China

GB/T307

0 (G)

6 (E)

5 (D)

4 (C)

2 (B)

ISO

ISO492

0

6

5

4

2

Sweden

SKF

0

P6

P5

P4

P2

Germany

DIN 620/2

P0

P6

P5

P4

P2

U.S.A.

ANSI B3.14

ABEC1

ABEC3

ABEC5

ABEC7

ABEC9

Japan

JIS B1514

0

6

5

4

2


Contrast of tolerance class for tapered roller bearing(metric size) in different countries

Country

Standard

Tolerance class

China

GB/T307

0

P6x

 

P5

P4

 

ISO

ISO492

0

6x

 

5

4

 

Sweden

SKF

0

CLN

 

P5

 

 

U.S.A.

ANSI

K

 

N

C

B

A

Japan

JIS

0

6x

6

5

4

 


Contrast of tolerance class for tapered roller bearing(inch size) in different countries

Country

Standard

Tolerance class

China

SFT

4

 

3

 

 

ISO

ISO492

4

 

3

0

00

Sweden

SKF

0

 

CL3

CL0

 

U.S.A.

ANSI

4

2

3

0

00

The standard manufacturing tolerance of SFT bearing is Class 0. Other tolerance grade can be supplied upon request

Tolerance of Class 0 radial bearing

Inner ring

d

dmp

Vdp

Vdmp

Bs

B1s

VBs

Kia

over

incl.

high

low

Dimension series

max

high

low

high

low

max

max

mm

µm

8, 9

0, 1

2, 3, 4

µm

µm

µm

µm

µm

max (µm)

2.5

10

0

-8

10

8

6

6

0

-120

0

-250

15

10

10

18

0

-8

10

8

6

6

0

-120

0

-250

20

10

18

30

0

-10

13

10

8

8

0

-120

0

-250

20

13

30

50

0

-12

15

12

9

9

0

-120

0

-250

20

15

50

80

0

-15

19

19

11

11

0

-150

0

-380

25

20

80

120

0

-20

25

25

15

15

0

-200

0

-380

25

25

120

180

0

-25

31

31

19

19

0

-250

0

-500

30

30

180

250

0

-30

38

38

23

23

0

-300

0

-500

30

40

250

315

0

-35

44

44

26

26

0

-350

0

-500

35

50

315

400

0

-40

50

50

30

30

0

-400

0

-630

40

60

400

500

0

-45

56

56

34

34

0

-450

0

-630

50

65

500

630

0

-50

63

63

38

38

0

-500

0

-800

60

70

630

800

0

-75

 -

 -

 -

 -

0

-750

 -

 -

70

80

800

1000

0

-100

 -

 -

 -

 -

0

-1000

 -

 -

80

90

1000

1250

0

-125

 -

 -

 -

 -

0

-1250

 -

 -

100

100

1250

1600

0

-160

 -

 -

 -

 -

0

-1600

 -

 -

120

120

1600

2000

0

-200

 -

 -

 -

 -

0

-2000

 -

 -

140

140

Outer ring

D

Dmp

VDp

VDmp

Cs

C1s

VCs

Kea

over

incl.

high

low

Dimension series

With oil seals

max

high

low

high

low

max

max

mm

µm

8, 9

0, 1

2, 3, 4

or shields

µm

µm

µm

µm

µm

max (µm)

6

18

0

-8

10

8

6

10

6

same as inner ring Bs, B1s, VBs

15

18

30

0

-9

12

9

7

12

7

15

30

50

0

-11

14

11

8

16

8

20

50

80

0

-13

16

13

10

20

10

25

80

120

0

-15

19

19

11

26

11

35

120

150

0

-18

23

23

14

30

14

40

150

180

0

-25

31

31

19

38

19

45

180

250

0

-30

38

38

23

 -

23

50

250

315

0

-35

44

44

26

 -

26

60

315

400

0

-40

50

50

30

 -

30

70

400

500

0

-45

56

56

34

 -

34

80

500

630

0

-50

63

63

38

 -

38

100

630

800

0

-75

94

94

55

 -

55

120

800

1000

0

-100

125

125

75

 -

75

140

1000

1250

0

-125

 -

 -

 -

 -

 -

160

1250

1600

0

-160

 -

 -

 -

 -

 -

190

1600

2000

0

-200

 -

 -

 -

 -

 -

220

2000

2500

0

-250

 -

 -

 -

 -

 -

250


Tolerance of Class 0 tapered roller bearing (metric size)

Cone and width

d

dmp

Vdp

Vdmp

Bs

Kia

Ts

T1s

T2s

over

incl.

high

low

max

max

high

low

max

high

low

high

low

high

low

mm

µm

µm

µm

µm

µm

µm

µm

µm

10

18

0

-12

12

9

0

-120

15

+200

0

+100

0

+100

0

18

30

0

-12

12

9

0

-120

18

+200

0

+100

0

+100

0

30

50

0

-12

12

9

0

-120

20

+200

0

+100

0

+100

0

50

80

0

-15

15

11

0

-150

25

+200

0

+100

0

+100

0

80

120

0

-20

20

15

0

-200

30

+200

-200

+100

-100

+100

-100

120

180

0

-25

25

19

0

-250

35

+350

-250

+150

-150

+150

-150

180

250

0

-30

30

23

0

-300

50

+350

-250

+150

-150

+150

-150

250

315

0

-35

35

26

0

-350

60

+350

-250

+150

-150

+150

-150

315

400

0

-40

40

30

0

-400

70

+400

-400

+200

-200

+200

-200

400

500

0

-45

45

34

0

-450

70

+400

-400

 

 

 

 

500

630

0

-50

50

38

0

-500

85

+500

-500

 

 

 

 

630

800

0

-75

75

56

0

-750

100

+600

-600

 

 

 

 

800

1000

0

-100

100

75

0

-1000

120

+750

-750

 

 

 

 

1000

1250

0

-125

 

 

0

-1250

120

+1000

-1000

 

 

 

 

1250

1600

0

-160

 

 

0

-1600

120

+1500

-1500

 

 

 

 

1600

2000

0

-200

 

 

0

-2000

120

+1500

-1500

 

 

 

 

Cup

D

Dmp

VDp

VDmp

Cs

Kea

over

incl.

high

low

max

max

high

low

max

mm

µm

µm

µm

µm

µm

18

30

0

-12

12

9

same as Bs

18

30

50

0

-14

14

11

20

50

80

0

-16

16

12

25

80

120

0

-18

18

14

35

120

150

0

-20

20

15

40

150

180

0

-25

25

19

45

180

250

0

-30

30

23

50

250

315

0

-35

35

26

60

315

400

0

-40

40

30

70

400

500

0

-45

45

34

80

500

630

0

-50

50

38

100

630

800

0

-75

75

55

120

800

1000

0

-100

100

75

120

1000

1250

0

-125

125

94

120

1250

1600

0

-160

160

120

120

1600

2000

0

-200

 

 

120

2000

2500

0

-250

 

 

120


Tolerance of Class 4 tapered roller bearing (inch size)

Cone

d

ds

over

incl.

high

low

mm

µm

 -

76.2

+13

0

76.2

101.6

+25

0

101.6

266.7

+25

0

266.7

304.8

+25

0

304.8

609.6

+51

0

609.6

914.4

+76

0

914.4

1219.2

+102

0

1219.2

 -

+127

0


Cup

D

Ds

Kia,Kea,Sia,Sea

over

incl

high

low

max

mm

µm

µm

 -

266.7

+25

0

51

266.7

304.8

+25

0

51

304.8

609.6

+51

0

51

609.6

914.4

+76

0

76

914.4

1219.2

+102

0

76

1219.2

 -

+127

0

76


Width

d

D

Ts

over

incl

over

incl

high

low

mm

µm

µm

 -

101.6

 -

 -

+203

0

101.6

266.7

 -

 -

+356

-254

266.7

304.8

 -

 -

+356

-254

304.8

609.6

 -

508

+381

-381

304.8

609.6

508

 -

+381

-381

609.6

 -

 -

 -

+381

-381

Tolerance of Class 0 tapered bore of radial bearing (tapered bore = 1:12)

d

dmp

Vdp

d1mp-dmp

over

incl

high

low

max

high

low

mm

µm

µm

µm

18

30

+21

0

13

+21

0

30

50

+25

0

15

+25

0

50

80

+30

0

19

+30

0

80

120

+35

0

25

+35

0

120

180

+40

0

31

+40

0

180

250

+46

0

38

+46

0

250

315

+52

0

44

+52

0

315

400

+57

0

50

+57

0

400

500

+63

0

56

+63

0

500

630

+70

0

 -

+70

0

630

800

+80

0

 -

+80

0

800

1000

+90

0

 -

+90

0

1000

1250

+105

0

 -

+105

0

1250

1600

+125

0

 -

+125

0

1600

2000

+150

0

 -

+150

0


Tolerance of Class 0 tapered bore of radial bearing (tapered bore = 1:30)

d

dmp

Vdp

d1mp-dmp

over

incl

high

low

max

high

low

mm

μm

μm

μm

80

120

+20

0

25

+40

0

120

180

+25

0

31

+50

0

180

250

+30

0

38

+55

0

250

315

+35

0

44

+60

0

315

400

+40

0

50

+65

0

400

500

+45

0

56

+75

0

500

630

+50

0

63

+85

0

630

800

+75

0

+100

0

800

1000

+100

0

+100

0

1000

1250

+125

0

+115

0

1250

1600

+160

0

+125

0

1600

2000

+200

0

+150

0

Clearance

SFT bearing radial clearance accords with the Chinese national standard GB/T 4604,
which is equal to ISO 5753

The clearances is classified into 5 groups, C2, C0, C3, C4, C5 with different applications
depending on customer's request

Radial clearance of deep groove ball bearing

d

C2

C0

C3

C4

C5

over

incl.

min.

max

min.

max

min.

max

min.

max

min.

max

mm

μm

2.5

6

1

8

5

15

10

20

15

25

21

33

6

10

2

9

6

17

12

25

19

33

27

42

10

14

2

10

6

19

13

26

21

35

30

48

14

18

3

12

8

21

15

28

23

37

32

50

18

24

4

14

10

23

17

30

25

39

34

52

24

30

5

16

11

24

19

35

29

46

40

58

30

40

6

18

13

29

23

40

34

53

46

66

40

50

6

19

14

31

25

44

37

57

50

71

50

65

7

21

16

36

30

50

45

69

62

88

65

80

8

24

18

40

35

60

54

83

76

108

80

100

9

27

22

48

42

70

64

96

89

124

100

120

10

31

25

56

50

83

75

114

105

145

120

140

10

38

30

68

60

100

90

135

125

175

140

160

15

44

35

80

70

120

110

161

150

210


Radial clearance of cylindrical bore self-aligning ball bearing

d

C2

C0

C3

C4

C5

over

incl

min

max

min

max

min

max

min

max

min

max

mm

μm

18

24

7

17

13

26

20

33

28

42

37

55

24

30

9

20

15

28

23

39

33

50

44

62

30

40

12

24

19

35

29

46

40

59

52

72

40

50

14

27

22

39

33

52

45

65

58

79

50

65

18

32

27

47

41

61

56

80

73

99

65

80

23

39

35

57

50

75

69

98

91

123

80

100

29

47

42

68

62

90

84

116

109

144

100

120

35

56

50

81

75

108

100

139

130

170

120

140

40

68

60

98

90

130

120

165

155

205

140

160

45

74

65

110

100

150

140

191

180

240


Radial clearance of tapered bore self-aligning ball bearing

d

C2

C0

C3

C4

C5

over

incl

min

max

min

max

min

max

min

max

min

max

mm

μm

 -

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

250

280

55

125

125

195

190

260

260

330

370

440

280

315

55

130

130

205

200

275

275

350

410

485

315

355

65

145

145

225

225

305

305

385

455

535

355

400

100

190

190

280

280

370

370

460

510

600

400

450

110

210

210

310

310

410

410

510

565

665

450

500

110

220

220

330

330

440

440

550

625

735


Radial clearance of tapered bore spherical roller bearing

d

C2

C0

C3

C4

C5

over

incl

min

max

min

max

min

max

min

max

min

max

mm

μm

14

18

10

20

20

35

35

45

45

60

60

75

18

24

10

20

20

35

35

45

45

60

60

75

24

30

15

25

25

40

40

55

55

75

75

95

30

40

15

30

30

45

45

60

60

80

80

100

40

50

20

35

35

55

55

75

75

100

100

125

50

65

20

40

40

65

65

90

90

120

120

150

65

80

30

50

50

80

80

110

110