1.3 bearing designation system

bearing designation system

1. Bearing Basics
Basic Bearing Designation System

2. SKF Bearing Designations

3. Bearing Designations are of two types
Basic Designations
Supplementary Designations

4. The basic designation identifies:
• Product type
• Standard design
• Size
The supplementary designation identifies:
• Alternative design (variants)
• Bearing components
• Types of special bearings
SKF Bearing Designations

5. The Supplementary Designations identify
Alternative Designs ( Variants )
Bearing Components
Type of Special Bearing
Supplementary designation consists of
Prefixes
 Suffixes

6. Width and Diameter Variations

7. ISO Standards
International
Organization for
Standardization
ISOISO

8. Basic Designation for Metric Bearings
Consists of 5 digits
First digit denotes Bearing Type
Second digit denotes Width /
Height
Third digit denotes OD
Fourth & fifth digits denote ID

9. Diameter Series

10. Relationship: Diameter and Width
Series

11. Dimension Series
Diameter Series
Width Series
Dimension Series
3
2
0
0 1 2 3
03
02
00
13
12
10
23
22
20 30
32
33

12. How the Designation System Works
Bearing types
Radial bearings, width (B, T)Thrust bearing, height (H)
Outside diameter (D)
Bearing size d/5
(30 mm bore diameter)

15. Bearing Type Designations:
Cylindrical Roller Bearings
NU NJ NUP
N NU + HJ NJ + HJ

16. Basic Series Designations:
Standard Inch Size Bearings
LLLL
Bearing
type
Bearing
series
Bore
1/8’s
of inch

17. Standard Inch Size Bearing Types
deep groove ball bearings
angular contact ball bearings
self-aligning ball bearings
cylindrical roller bearings
RLSRMS
ALSAMS
RL RM
CRLCRM
L: light series M: medium series

18. Example : Inch Size Designations
deep groove ball, d = 1 1/4˝, light
cylindrical roller, d = 3˝, medium
self-aligning ball, d = 2˝, light
angular contact ball, d = 5˝, light
RLS 10
CRM 24
RL 16
ALS 40
thrust ball, d = 2 1/2˝ O 20

19. Inch Size Taper Roller Bearings:
Cups and Cones
Inch taper roller
bearings are designed
around roller & cage
assemblies, and belong to
families
: Basic design
(family)

20. The supplementary designation identifies:
• Variants – deviations from standard design
• Grouped into four categories
• Added to basic designation in a specific order, where
more than one deviation applies
SKF Bearing Designations

21. Categories of Supplementary Designations
Category 1 : Modified Internal Design
Category 2 : Modified External Design
Category 3 : Modified Cage Design
Category 4 : Modifications to enhance Performance

22. Category 1: Modified Internal Design
A AC
B BE
C and combinations thereof such as CA/CB/CC
CAC
D
E EC

23. Category 1: Modified Internal Design
A : * Transitional Designation / changed after a period
e.g., 4210 A : DRDGBB without filling slot
* Contact Angle 30
0
in SRACBB
e.g., 7056 A
B : * Contact Angle 40
0
in SRACBB
e.g., 7210 B
* Steep Contact Angle in TRB
e.g., 32210 B

24. Category 1: Modified Internal Design
C : * Contact Angle 15
0
in SRACBB
e.g., 7012 C
* SRB with loose Guide Flange , symmetrical
rollers and pressed steel cage of window design
AC :* Contact Angle 25
0
in SRACBB
e.g., 7210 AC

D :* DRACBB with two part Inner Ring and
Contact Angle of 45
0

25. Category 1: Modified Internal Design
E : * Larger ball or Roller diameter
e.g., 29320 E
CA :* SRB with loose guide ring but two integral flanges
with machined brass cage e.g., 23180 CA/W33
* ACBB for universal mounting with low axial
clearance when mounted in pair
CAC :* SRB of CA design but with improved roller
guidence

26. Category 1: Modified Internal Design
CB : * ACBB for universal mounting with axial
clearance larger than CA when mounted in pair
CC :* ACBB for universal mounting with axial
clearance larger than CB when mounted in pair
* SRB of C design but with improved roller
guidance
EC : * Single Row CRB with a greater number of
larger rollers than the original design, and
increased axial load carrying capacity in
Flanged executions
e.g., NU 320 EC / NJ 320 EC

27. Category 1: Modified Internal Design
GA : * ACBB for universal mounting with light
preload when mounted in pair
GB :* ACBB for universal mounting with axial
preload larger than GA when mounted in pair

GC : * ACBB for universal mounting with axial
preload larger than GB when mounted in pair

28. Category 2: Modified External Design
K : * Tapered Bore ( Taper 1 : 12 )
K 30: * Tapered Bore ( Taper 1 : 30 )
N : * Snap ring groove on bearing outer diameter
N1 : * One locating slot on outside edge of outer ring
N2 : * Two diametrically opposite locating slots on
outside edge of outer ring
N4 : * N + N2. Locating slots on side opposite to
snap ring groove
N6 : * N + N2. Locating slots on same side as snap
ring groove
NR : * Snap ring groove on bearing outer diameter
along with an appropriate snap ring

29. Category 2: Modified External Design
Tapered Bore Suffixes
Suffix K
Suffix K30
Taper 1:12
Taper 1:30

30. Category 2: Modified External Design
P : * SRB with two part outer ring
PR : * SRB with two part outer ring, with calibrated
spacer in between
R : * Integral flange on outer ring outer diameter
- RS: * NRB fitted with synthetic rubber seal on
one side
- 2RS: * NRB fitted with synthetic rubber seals on
two sides
- RS1: * Rubbing seal of synthetic rubber with sheet
steel reinforcement fitted on one side
- 2RS1: * Rubbing seal of synthetic rubber with sheet
steel reinforcement fitted on both sides

31. Category 2: Modified External Design
-RS2: * Rubbing seal consisting of sheet steel washer
with vulcanized rubber fitted on one side
- 2RS1: * Rubbing seal consisting of sheet steel washer
with vulcanized rubber fitted on both sides
-RZ: * Ball bearing with low friction seal consisting
of sheet steel washer with vulcanized rubber
fitted on one side
-2RZ: * Ball bearing with low friction seal consisting
of sheet steel washer with vulcanized rubber
fitted on both sides

32. Category 2: Modified External Design
X : * One or more of bearing external dimensions
altered to fully comply with ISO standards
- Z: * Metallic non-rubbing seal fitted on one side
- 2Z: * Metallic non-rubbing seal fitted on both sides

33. Z RZ2Z
N
2RZ
NRRS1 2RS1
Suffixes: Seals and Shields

34. Category 3: Modified Cage Design
F : * Machined Steel or SG Iron cage
FA : * F Cage centred on outer ring
FB : * F Cage centred on inner ring
FE : * Machined Steel Cage phosphated
H : * Pressed cage of hardened sheet steel
J : * Pressed cage of unhardened sheet steel
JA : * J Cage centred on outer ring
JE : * J Cage phosphated
L : * Machined light alloy cage
LA : * L Cage centred on outer ring
LB : * L Cage centred on inner ring

35. Category 3: Modified Cage Design
Cage Types

36. Category 3: Modified Cage Design
M : * Machined Brass cage
MA: * M Cage centred on outer ring
MB : * M Cage centred on inner ring
MP: * M Cage window type
P : * Moulded cage made of glass fibre reinforced
polyamide 6.6
TN: * Moulded cage made of plastic
Y : * Pressed Brass cage
V : * Full complement bearing ( without cage )

37. Category 4: Modifications to enhance Performance
/CL7A: * Standard SKF quality for Pinion Bearings
/CL7C: * Special SKF quality for Pinion Bearings
/CN : * Normal internal clearance. This usually used
followed by H/M/L/P to denote part or
displaced range e.g.:
CNH : * Upper half of Normal
CNM : * Two middle quarters of Normal
CNL : * Lower half of Normal
CNP : * Upper half of Normal &
Lower half of C3

38. Category 4: Modifications to enhance Performance
/C1: * Internal clearance less than C2
/C2: * Internal clearance less than Normal
/C3: * Internal clearance more than Normal
/C4: * Internal clearance more than C3
/C5: * Internal clearance more than C4
A letter H/M/L/P following the clearance
designation denotes part or displaced range.
/C01: * Reduced tolerance for running accuracy of I/R
/C02: * Extra reduced tolerance for running accuracy
of I/R : less than C01

39. Category 4: Modifications to Enhance
Performance
C1clearance less than C2
C2clearance less than Normal
C3clearance greater than Normal
C4clearance greater than C3
C5clearance greater than C4
Radial internal
clearance
Axial internal
clearance
Suffix Range for Internal Clearances

40. Category 4: Modifications to enhance Performance
/C03: * Reduced tolerance for running accuracy of O/R
/C04: * Extra reduced tolerance for running accuracy
of O/R : less than C03
/C05: * C01 + C03
/C06: * C02 + C03
/C05: * C01 + C04
/C06: * C02 + C04
/C10: * Reduced tolerance for bore & OD. In case of
tapered bore, refers to only OD.
/C20: * Bore diameter tolerance less than C10

41. Category 4: Modifications to enhance Performance
/C30: * Reduced bore diameter tolerance, towards
standard minimum limit.
/C40: * OD tolerance less than C10
/C50: * Reduced OD tolerance, towards standard
minimum limit.
/C60: * C20 + C50
/C70: * C20 + C40
/C80: * Reduced height tolerance for thrust bearings
/C15: * C10 + C05
/C18: * C10 + C08
/C78: * C70 + C08

42. Category 4: Modifications to enhance Performance
/DB: * Two single row DGBB/ACBB/TRB, paired
for mounting in back-to-back arrangement.
/DF: * Two single row DGBB/ACBB/TRB, paired
for mounting in face-to-face arrangement.
/DT: * Two single row DGBB/ACBB/TRB, paired
for mounting in tandem
/HA: * Case hardened bearing or bearing components.
For closer identification, it is followed by one of
following numbers : 0/1/2/3/4/5/6/7 e.g.,
1Both rings
2Outer ring
5 Rolling elements etc.

43. Category 4: Modifications to enhance Performance
/HT: * Bearing supplied with High Temperature
( upto +130
0
C) grease
/LHT: * Bearing supplied with Low as well as High
Temperature ( -40 to +140
0
C) grease
/LT: * Bearing supplied with Low Temperature
( upto -50
0
C) grease
/MT: * Bearing supplied with Medium Temperature
( -30 to +110
0
C) grease

44. Category 4: Modifications to enhance Performance
/P4: * Dimensional and running accuracy to ISO
tolerance class 4.
/P4A: * Dimensional accuracy to ISO tolerance class 4
and and running accuracy to AFBMA class 9.
/P5: * Dimensional and running accuracy to ISO
tolerance class 5 ( More accurate than P6).
/P6: * Dimensional and running accuracy to ISO
tolerance class 6.
/P43: * P4 + C3
/P52: * P5 + C2
/P62: * P6 + C2
/PA9: * Dimensional and running accuracy to AFBMA
class 9.

45. Category 4: Modifications to enhance Performance
/SP: * Special Precision, dimensional accuracy approx.
corresponding to P5 and running accuracy
approx. to P4
/S0: * Bearing ring dimensionally stabilized to optg.
temperatures upto + 150
0
C
/S1: * Bearing ring dimensionally stabilized to optg.
temperatures upto + 200
0
C
/S2: * Bearing ring dimensionally stabilized to optg.
temperatures upto + 250
0
C
/S3: * Bearing ring dimensionally stabilized to optg.
temperatures upto + 300
0
C
/S4: * Bearing ring dimensionally stabilized to optg.
temperatures upto + 350
0
C

46. Category 4: Modifications to enhance Performance
/UP: * Ultra Precision, dimensional accuracy approx.
corresponding to P4 and running accuracy
better than P4
/W20: * Three lubrication holes in outer ring
/W33: * Lubricating groove and three lubrication holes
in outer ring
/Vxxxx: * V plus a second letter followed by a three figure
number denoting variants not covered by
“logical” supplementary designations. e.g:
VA 201: Bearings for Kiln Trucks
VA 301: Bearings for Traction Motors

47. Category 4: Modifications to Enhance
Performance
P0 1 Normal P0
P6 3 P6 P6
P5 5 P5 P5
P4 7 SP P4
P4A
P2 9 UP P2
PA9A
Tolerance
ISO
Tolerance
ABEC
Tolerance
SKF
Tolerance
RHP / NSK

48. SKF Bearing Designations
The sequence of writing the designations:
• Prefix – if any
• Basic designation
• Supplementary designation of category 1
• Supplementary designation of category 2
• Supplementary designation of category 3
• Stroke
• Supplementary designation of category 4

49. SKF Bearing Designations

50. SKF Bearing Designations
The sequence of writing the designations:
• Where two suffixes follow one another, the first ending
with a figure and the second starting with one, a stroke
is to be used
e.g: 6310 / C4/ 630251
• Where a suffix for a divided clearence range is followed
by a suffix for type of grease, a stroke is to be used
e.g : 6205-2Z/C2L/HT51 (C2L + HT51)
but : 6205-2Z/C2 LHT51 (C2 + LHT51)

52. LetterYearYearYearYear LetterYearYearYearYear
A 1910193419581981 N 1922194619701993
B 1911193519591982 O 1923194719711994
C 1912193619601983 P 1924194819721995
D 1913193719611984 R 1925194919731996
E 1914193819621985 S 1926195019741997
F 1915193919631986 T 1927195119751998
G 1916194019641987 U 1928195219761999
E 1917194119651988 V 19291953 – –
J 1918194219661989 W 1930195419772000
K 1919194319671990 X 1931195519782001
L 1920194419681991 Y 1932195619792002
M 1921194519691992 Z 1933195719802003
Date Codes
The Year Letter to be marked on a bearing or a bearing accessory shall
comprise a single letter in accordance with the table below