Designation system

The designations of most SKF rolling bearings follow a system that may consist of a basic designation with or without one or more prefixes and/or suffixes (→ Basic bearing designation system).
An example and the applicable options for four-point contact ball bearings are given below.
Basic bearing designation system


QJ 318 N2PHASwhereQJ 318 =Test Designation 1
N2 =Test Designation 2
PHAS =Test Designation 4
Test Designation 1Prefixes (n.a.)

Test Designation 2Basic designation
Listed in table 1

Catalogue image - Test Designation 3Suffixes - Internal design (n.a.)

Test Designation 4Suffixes - External design (seals, snap ring groove, etc.)
N2Two locating slots (notches) in one outer ring side face, 180° apart

Catalogue image - Test Designation 5Suffixes - Cage design
FAMachined steel cage, outer ring centred
MAMachined brass cage, outer ring centred.
PHASGlass fibre reinforced PEEK cage, with lubrication grooves in the guiding surface, outer ring centred

Catalogue image - Test Designation 6.1Suffixes - Materials, heat treatment (n.a.)

Test Designation 6.2Suffixes - Accuracy, clearance, preload, quiet running
P6Dimensional and geometrical tolerances to class P6
P62P6 + C2
P63P6 + C3
P64P6 + C4
P6 + CNL
Axial internal clearance in the lower half of the Normal range
C2Axial internal clearance smaller than Normal
C2HAxial internal clearance in the upper half of the C2 range
C2LAxial internal clearance in the lower half of the C2 range
C3Axial internal clearance greater than Normal
C4Axial internal clearance greater than C3

Catalogue image - Test Designation 6.3Suffixes - Bearing sets, matched bearings (n.a.)

Test Designation 6.4Suffixes - Stabilization
Bearing rings heat stabilized for operating temperatures ≤ 200 °C (390 °F)

Test Designation 6.5Suffixes - Lubrication (n.a.)

Test Designation 6.6Suffixes - Other variants
309829Larger balls
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