1.3 bearing designation system

Bearing Basics

Basic Bearing Designation System

SKF Bearing Designations

Bearing Designations are of two types

Basic Designations Supplementary Designations

The basic designation identifies:

• Product type• Standard design• Size

The supplementary designation identifies:

• Alternative design (variants)• Bearing components• Types of special bearings


The Supplementary Designations identify

Alternative Designs ( Variants ) Bearing Components Type of Special Bearing

Supplementary designation consists of

Prefixes Suffixes

Width and Diameter Variations

ISO Standards

International Organization forStandardization

ISOISO

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

Diameter Series

Relationship: Diameter and Width Series

Dimension Series

Diameter Series Width Series Dimension Series

3

2

0

0 1 2 3

03

02

00

13

1210

23

22

20 3032

33

How the Designation System WorksBearing types

Radial bearings, width (B, T) Thrust bearing, height (H)

Outside diameter (D)

Bearing size d/5

(30 mm bore diameter)

Bearing Type Designations: Cylindrical Roller Bearings

NU NJ NUP

N NU + HJ NJ + HJ

Basic Series Designations: Standard Inch Size Bearings

L L L L

Bearingtype

Bearingseries

Bore1/8’s

of inch

Standard Inch Size Bearing Types

deep groove ball bearings

angular contact ball bearings

self-aligning ball bearings

cylindrical roller bearings

RLS RMS

ALS AMS

RL RM

CRL CRM

L: light series M: medium series

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

Inch Size Taper Roller Bearings: Cups and Cones

Inch taper rollerbearings are designedaround roller & cageassemblies, and belong to families

: Basic design(family)

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


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

Category 1: Modified Internal Design

A AC

B BE

C and combinations thereof such as CA/CB/CCCAC

D

E EC


A : * Transitional Designation / changed after a period e.g., 4210 A : DRDGBB without filling slot * Contact Angle 300 in SRACBB e.g., 7056 A

B : * Contact Angle 400 in SRACBB e.g., 7210 B * Steep Contact Angle in TRB e.g., 32210 B


C : * Contact Angle 150 in SRACBB e.g., 7012 C * SRB with loose Guide Flange , symmetrical rollers and pressed steel cage of window design

AC :* Contact Angle 250 in SRACBB e.g., 7210 AC D :* DRACBB with two part Inner Ring and Contact Angle of 450


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


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


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

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 diameterN1 : * One locating slot on outside edge of outer ringN2 : * Two diametrically opposite locating slots on outside edge of outer ring N4 : * N + N2. Locating slots on side opposite to snap ring grooveN6 : * N + N2. Locating slots on same side as snap ring grooveNR : * Snap ring groove on bearing outer diameter along with an appropriate snap ring

Category 2: Modified External DesignTapered Bore Suffixes

Suffix K

Suffix K30

Taper 1:12

Taper 1:30


P : * SRB with two part outer ringPR : * SRB with two part outer ring, with calibrated spacer in betweenR : * 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


-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


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

Z RZ2Z

N

2RZ

NRRS1 2RS1

Suffixes: Seals and Shields

Category 3: Modified Cage Design

F : * Machined Steel or SG Iron cageFA : * F Cage centred on outer ringFB : * F Cage centred on inner ring FE : * Machined Steel Cage phosphatedH : * Pressed cage of hardened sheet steel J : * Pressed cage of unhardened sheet steel JA : * J Cage centred on outer ringJE : * J Cage phosphatedL : * Machined light alloy cageLA : * L Cage centred on outer ringLB : * L Cage centred on inner ring


Cage Types


M : * Machined Brass cageMA : * M Cage centred on outer ringMB : * M Cage centred on inner ring MP : * M Cage window typeP : * Moulded cage made of glass fibre reinforced polyamide 6.6 TN : * Moulded cage made of plasticY : * Pressed Brass cageV : * Full complement bearing ( without cage )

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


/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

Category 4: Modifications to Enhance Performance

C1 clearance less than C2C2 clearance less than NormalC3 clearance greater than NormalC4 clearance greater than C3C5 clearance greater than C4

Radial internalclearance

Axial internalclearance

Suffix Range for Internal Clearances


/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


/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


/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., 1 Both rings

2 Outer ring 5 Rolling elements etc.


/HT : * Bearing supplied with High Temperature ( upto +1300 C) grease /LHT : * Bearing supplied with Low as well as High Temperature ( -40 to +1400 C) grease/LT : * Bearing supplied with Low Temperature ( upto -500 C) grease/MT : * Bearing supplied with Medium Temperature ( -30 to +1100 C) grease


/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.


/SP : * Special Precision, dimensional accuracy approx. corresponding to P5 and running accuracy

approx. to P4/S0 : * Bearing ring dimensionally stabilized to optg.

temperatures upto + 1500C /S1 : * Bearing ring dimensionally stabilized to optg.



temperatures upto + 3000C/S4 : * Bearing ring dimensionally stabilized to optg.

temperatures upto + 3500C


/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

Category 4: Modifications to Enhance Performance

P0 1 Normal P0

P6 3 P6 P6

P5 5 P5 P5

P4 7 SP P4P4A

P2 9 UP P2PA9A

ToleranceISO

ToleranceABEC

ToleranceSKF

ToleranceRHP / NSK


The sequence of writing the designations:

• Prefix – if any

• Basic designation

• Supplementary designation of category 1



• Stroke



SKF Bearing DesignationsThe 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)

Letter Year Year Year Year Letter Year Year Year Year

A 1910 1934 1958 1981 N 1922 1946 1970 1993B 1911 1935 1959 1982 O 1923 1947 1971 1994C 1912 1936 1960 1983 P 1924 1948 1972 1995

D 1913 1937 1961 1984 R 1925 1949 1973 1996E 1914 1938 1962 1985 S 1926 1950 1974 1997F 1915 1939 1963 1986 T 1927 1951 1975 1998

G 1916 1940 1964 1987 U 1928 1952 1976 1999E 1917 1941 1965 1988 V 1929 1953 – –J 1918 1942 1966 1989 W 1930 1954 1977 2000

K 1919 1943 1967 1990 X 1931 1955 1978 2001L 1920 1944 1968 1991 Y 1932 1956 1979 2002M 1921 1945 1969 1992 Z 1933 1957 1980 2003

Date CodesThe Year Letter to be marked on a bearing or a bearing accessory shall

comprise a single letter in accordance with the table below

Engineering

1.3 bearing designation system