Materials Used for SKF Rolling Bearings
Bearing rings and rolling elements
Through-hardening steels
Case-hardening steels
Carbon chromium steel
containing approximately
1 % carbon and
1,5 % chromium
Chromium-nickel alloyed steel
and manganese-chromium
alloyed steel containing
approximately 0,15 % carbon
2013-03-17 SKF Slide 1 WE 201
SKF Reliability Maintenance Institute
Heat Treatments
Advantages
Martensite hardening
Bainitic hardening
Less costly
Tough structure
Fixture can be used to
reduce distortion
Automatic dimensional
stability
Case hardening
Hard surface and soft core
resists through cracking
Highest compressive
residual surface stresses
Compressive residual
surface stresses
Disadvantages
Martensite hardening
Highest risk of propagation
of surface cracks
Bainitic hardening
Somewhat more costly
than martensite
Lower hardness
2013-03-17 SKF Slide 2 WE 201
SKF Reliability Maintenance Institute
Case hardening
Time consuming and
costly process
Heat treat and hardness
Martensite-hardened material
(through hardening)
Bainite-hardened material
(through hardening)
Tensile stresses 50 100 MPa
Compressive stresses 50 100 MPa
60 HRC
59 HRC
59 HRC
58 HRC
Case-hardened material
Compressive stresses 200 400 MPa
60 HRC
35 HRC
2013-03-17 SKF Slide 3 WE 201
SKF Reliability Maintenance Institute
: Tensile
stresses
: Compressive
stresses
Dimensional Stability
Change in diameter (m/100 mm)
Martensite
Bainite
Hours
Holding time at 200 C (392 F)
2013-03-17 SKF Slide 4 WE 201
SKF Reliability Maintenance Institute
Dimensional stability designation
Stabilization
Class
Operating
Temperature
Hardness
HRC
SN
up to 120 C (248 F)
59 to 63
S0
up to 150 C (302 F)
58 to 62
S1
up to 200 C (392 F)
57 to 61
S2
up to 250 C (482 F)
56 to 60
S3
up to 300 C (572 F)
54 to 58
S4
up to 350 C (662 F)
50 to 54
2013-03-17 SKF Slide 5 WE 201
SKF Reliability Maintenance Institute
The Principle SKF Rolling Bearing Range
Ball bearings
Roller bearings
2013-03-17 SKF Slide 6 WE 201
SKF Reliability Maintenance Institute
Ball and Roller Bearing Ranges
Ball bearings
Deep groove Angular
contact
2013-03-17 SKF Slide 7 WE 201
SKF Reliability Maintenance Institute
Self-aligning
Roller bearings
Cylindrical Taper
Needle
Spherical
Load Capabilities
Load carrying capacity
is expressed as the basic
dynamic load rating
2013-03-17 SKF Slide 8 WE 201
SKF Reliability Maintenance Institute
Relative Speed Limitations
r/min
Oil lubrication
speed rating
Grease lubrication
speed rating
2013-03-17 SKF Slide 9 WE 201
SKF Reliability Maintenance Institute
Bearing
speed limit
Bearing components
Seal
Rolling Elements
Inner Ring
Outer Ring
Cage
Seal
2013-03-17 SKF Slide 10 WE 201
SKF Reliability Maintenance Institute
Bearing terminology...
Bore Surface
Outside
Diameter
O.D.
Bore
I.D.
O.D. Surface
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SKF Reliability Maintenance Institute
Bearing terminology
Side Faces
Inner Ring Land
(Shoulder)
Inner Ring Raceway
Outer Ring Raceway
Outer Ring Land
(Shoulder)
2013-03-17 SKF Slide 12 WE 201
SKF Reliability Maintenance Institute
Catalog dimensions
Dd
2013-03-17 SKF Slide 13 WE 201
SKF Reliability Maintenance Institute
Bearing terminology for a spherical roller bearing
Outer Ring
Inner Ring
Cage
Inner Ring
Raceway
Guide Ring
Rolling
Element
Side Faces
2013-03-17 SKF Slide 14 WE 201
SKF Reliability Maintenance Institute
W33 Lubrication
Groove and Hole
Cage Variants
Polyamide
cage
2013-03-17 SKF Slide 15 WE 201
SKF Reliability Maintenance Institute
Window-type
sheet steel cage
Window-type
solid brass cage
Pressed cages
2013-03-17 SKF Slide 16 WE 201
SKF Reliability Maintenance Institute
Lightweight
High strength
No operating
temperature limit
High vibration and
acceleration resistance
Sensitive to
poor lubrication
Machined cages: brass
2013-03-17 SKF Slide 17 WE 201
SKF Reliability Maintenance Institute
Very high strength
Very high vibration and
acceleration resistance
Suitable for very high
speed in connection
with circulating oil
Relatively (very)
expensive
Molded cages: polyamide
2013-03-17 SKF Slide 18 WE 201
SKF Reliability Maintenance Institute
Lightweight
High elasticity
Good sliding properties
Good marginal
lubrication properties
Operating temperature
< +120 C
