Bearing Training Course
NSK Global Quality
NSK International (Singapore) Pte Ltd
Philippine Representative Office
Unless otherwise specifically noted, the competitive information
contained in this presentation is gathered from legally permissible
sources, including, but not limited to, public records, electronic searches,
unsolicited customer or end-user feedback, and industry analysis.
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Bearing Refresher Course
• Introduction
• Bearing Elements
• Internal Clearance and Tolerance
• Bearing Types and Nomenclature
• Proper Maintenance, Handling, Installation
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Why Use Bearings?
10 kg
Sliding Friction
More Friction
Rolling Friction
Rolling Elements:
Less Friction
10 kg
➢
➢
Reduce Friction
Saves Energy!
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Bearing Components
⚫ Outer Ring
⚫ Rolling Element
⚫ Inner Ring
⚫ Raceway
⚫ Cage
Inner ring, outer ring and rolling elements:
Standard material is High Carbon Chromium Steel
Cage: Steel, Brass, or Plastic
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Rolling Elements
Roller
Ball
Point contact
Line contact
High speed
Moderate speed
Light to moderate loads
Heavy loads
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Rolling Elements
Roller
Ball
Point contact
Line contact
High speed
Moderate speed
Light to moderate loads
Heavy loads
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Bearing Dimension
Chamfer
Radius
Width
Bore
Diameter
or Inside
Diameter
Outside
Diameter
Shaft
Bearing
Housing
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Internal Clearance
For 6310 ball bearing
Normal clearance: 6-23 microns
C3 clearance:
18-36 microns
CM clearance:
9-17 microns
1 micron
Human Hair
Approx.
90 microns
1 micron = 0.001 mm
CLEARANCE CLASS
C1 Clearance less than C2
C2 Clearance less than CN
CM Motor Clearance
CN Normal Clearance
C3 Clearance greater than CN
C4 Clearance greater than C3
C5 Clearance greater than C4
*Note: CM is motor clearance, not motorcycle clearance
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Internal Clearance
*During operation
Small Clearance
Wide
Load zone
Large Clearance
Narrow
Load zone
Smaller Rolling Element Load =
Smaller Surface Pressure
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Effective Internal Clearance
Operating
Temperature!
Outer Ring
δhousing
Δ0
Δf
Δ
δt
δshaft
Roller
Δ0 : Geometrical Clearance, Initial Clearance
Δf : Residual internal clearance , Clearance after
Mounting
Δ : Effective internal clearance, Clearance during
operation
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Internal Clearance
Relationship between clearance and bearing life
Abrupt life degradation
115％
100％
Flaking
Seizure
Too Large Clearance
Too Small Clearance
Preload
Clearance Selection Considerations
-Noise
-Vibration
-Running Accuracy
-Heat Generation
-Fit Conditions
0
Clearance
*Note: Knowing the
application will help us
recommend the
clearance to use
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Shaft and Housing Standard Fits
Tight
Loose
Loose
Tight
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Bearing Tolerance
Example: 6310 bearing
▪
Dimensional tolerance
(to mount bearing onto shaft or
housing)
27
P2 P4 P5
P6 P0
-5
▪
P0 P6 P5 P4 P2
-8
Running accuracy
(run-out of rotating machine)
-10
-13
-15
110
-3
50
-12
-10
-8
-6
Note:
P4 & P2 is usually for Angular Contact
Inside
Diameter
P0
P6
P5
P4
P2
Normal Tolerance
Higher Tolerance than P0
Higher Tolerance than P6
Higher Tolerance than P5
Higher Tolerance than P4
Min.
49.988
49.90
49.992
49.994
49.997
Max.
50
50
50
50
50
Outside
Diameter
Min.
109.985
109.987
109.99
109.992
109.995
Max.
110
110
110
110
110
Higher
Speeds
↓
Higher
tolerance
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Bearing Tolerance
Normal Tolerance
Higher Tolerance
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Bearing Arrangements
Radial or
Normal
Load
Axial or Thrust
Load
Free End Bearing
-Supports Radial load
-Relieves shaft expansion
Fixed-End Bearing
-Supports Radial and
Axial Load
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Bearing Part Numbering
Prefix
Basic Number
Suffixes
Internal Design
Special
Design
Symbol
Type
Dimension
Series
Width
Series
Bore
Code
Diameter
Series
+
Contact
Angle
For
ACBB
and TRB
Material
Cage
External features
Arrangement
Clearance/Preload
Tolerance
Special Specification
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Bearing Part Numbering
Bearing Type
Dimension Series
Deep Groove
6
00, 02, 03, 04, 18, 19,
10
Angular
Contact
7
02, 03, 19, 10
Double-row
ACBB
5
3
02, 03
Self Aligning
(1)
02, 03, 22, 23
Cylindrical
NU
NJ
02, 03, 04, 19, 10, 29,
22, 23, 30, 31, 49
Tapered
3
02, 03, 29, 20, 22, 23,
30, 31, 32
Spherical
2
03, 22, 23, 39, 30, 31,
32, 40, 41
Bore Code
Suffixes (Auxiliary symbols)
Contact Angle
A = 30o, B = 40o
C = 15o
Internal Design
E, EA, C, CD, CA
Cage
W or none: Steel
M: Brass
T: Plastic
External Features
ZZ: 2 metal shields
DDU: 2 rubber seals
K, K30: tapered bore
04 to 96
d=code x 5
Combination
DB, DF, DT
SU, DU (universal)
> 480 mm
e.g. 240/600
Clearance
C2, CM, C3, C4
Not indicated: CN
Tolerance
P6, P5, P4, P2
Not indicated: P0
< 10 mm
e.g. 609
00 = 10 mm
01 = 12 mm
02 = 15 mm
03 = 17 mm
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Common Bearing Types
Radial Bearings
Ball Bearings
Roller Bearings
Deep Groove
Cylindrical
Angular Contact
Tapered Roller
Self Aligning
Spherical Roller
Thrust Bearings
Thrust Ball Bearing
Thrust Roller Bearing
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Deep Groove Ball Bearing
Features:
• Radial and axial loads in both directions
• Light to moderate load
• High speed and low torque
• Open, with closures (shields or seals)
Open Type
With Closures
Non-contact Type
ZZ
(metal shield)
VV
(rubber seal)
Contact Type
DDU
(rubber seal)
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Bearing Part Numbering
Dimension Series
6
Type
2
Enclosure
05
Bore Number
ZZ
CM
Clearance
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Angular Contact Ball Bearing
Features:
• Radial and axial loads in one direction
• Light to moderate load
• High speed
• Used in pairs or matched set
DB (back-to-back)
DF (face-to-face)
DT (tandem)
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Bearing Part Numbering
Dimension Series
7
Type
0
Contact Angle
05
Bore Number
C
Combination
TYN
Cage Material
DU
Tolerance
L
P4Y
Preload
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Self-Aligning Ball Bearing
Features:
• Double-row with spherical outer raceway
• Straight or tapered bore
• Accommodates misalignment
• Able to withstand increased misalignment
(4 - 7 o)
Cylindrical Bore
Ball protrusion occurs
in some series
Tapered Bore K
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Self-Aligning Ball Bearing
Deflected Shaft
Seat out of Square
Deflected Housing
Seats Offset
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Cylindrical Roller Bearing
Features:
• Heavy radial load
• Zero or limited axial load
• Separable rings (axial displacement)
• Moderate speed
• Matched and interchangeable clearances
NU
N
No Axial Load
NJ
NF
Axial Load in One Direction
NUP
NH
Axial Load in Two Directions
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Bearing Part Numbering
Dimension Series
NU
Type
3
Cage Material
18
Bore Number
M
C3
Clearance
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Tapered Roller Bearing
Features:
• Heavy radial and axial loads
• Separable cup/cone
• Used in pairs
• Metric (HR=high capacity) and Inch design
DB + KLR mount
DF + K mount
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Bearing Part Numbering
Type
HR
NSK High Capacity
3
Bore Number
02
Dimension Series
10
J
O.R. ISO Conforming
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Spherical Roller Bearing
Features:
• Heavy radial and axial loads
• Self-aligning capability
• Lubrication groove and oil holes
• Tapered or cylindrical bore
• NSKHPS “High Performance Standard” design
EA Design
C and CD Design
CA Design
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Spherical Roller Bearing
Misaligned Housings
Shaft Bending or Defection
Dynamic Vibration
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Bearing Part Numbering
Lubrication
Dimension Series
2
Type
40
Groove
Internal Design
30
Bore Number
CA
M
Cage Material
E4
Stabilization Temp.
C3
S11
Clearance
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Other bearing types
Double-Row ACBB
4-point Contact BB
Needle Roller Bearing
•
•
•
•
•
•
Back-to-back
Slightly narrower than
matched pairs
•
No radial load
Thrust load on both
directions
Split inner ring
•
Low section height
Long slender needles
(L=3-10d)
IR, OR, Cage and
roller assemblies
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Thrust Bearings
Thrust Ball
Bearings
Spherical Roller
Thrust Bearing
Cylindrical and Tapered
Roller Thrust Bearings
•
•
•
•
•
•
•
Axial load only
With flat or aligning
seats
Single or double
direction
•
Self aligning
E type with pressed
steel cage
M type with brass cage
Heavy axial load
Machined brass cages
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Bearing units
Pillow Block
Bearing Units = Housing + Insert
Insert =
Ball Bearing
of 62xx or
63xx series
Square Flange
Take –up Unit
Oval Flange
Circular Flange
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Bearing Housing and Accessories
Plummer block housing
• Cast iron/steel
• Split or one-piece
• Stepped/through shaft
• Straight /tapered bore bearings
• 2 or 4 bolt holes
• Labyrinth/contact seal
Sleeves and locking device
• Adapter/ withdrawal
• Metric or inch
• With/without oil injection holes
• Lock washers
• Nuts
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PROPER HANDLING AND MAINTENANCE
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Proper Handling
1. Keep Bearings and Surrounding Area Clean
•
•
Prevent entry of dust and dirt as it can have
harmful effects on Bearings
Keep the bearing and environment as clean as
possible
2.
Careful Handling
•
•
Heavy shocks may cause bearings to be
scratched or damaged.
Excessively strong impacts may cause
brinelling, breaking, or cracking
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Proper Handling
3. Prevent Corrosion
• Keep hands clean when handling
bearings
• Wear gloves if possible
• Pay attention to corrosive gases
4.
Proper Bearing Storage
• Moisture-free
• Avoid direct sunlight
• Make sure to prevent rust
• Proper stacking
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Form and Dimension
A
1
B
C
A B C
2
Housing
3
4
bore ᶲ
Shaft
ᶲ
Use a micrometer!
Diameter
Plane
A
B
C
1
2
3
4
Multi-row bearings need more planes of measurement
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Shaft Inspection and Housing Inspection
▪ Check diameter and form tolerances
Small shaft diameter:
The bearing load distribution
becomes small, so it causes
premature damage.
Oversized shaft diameter:
Clearance is lost, all rolling
elements are in contact with the
raceway
Creep will
happen
Loss of
clearance,
inner ring
may crack
Large diameter variation of among rows:
A specific row of bearing receives
large load and causes premature damage.
Shaft wobble,
loss of
clearance
▪ Check surface condition
> Dents, nicks, rust and poor roughness can induce creep
→ Smooth out imperfections with an oil stone or emery cloth
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Housing Inspection
▪ Check diameter and form tolerances
Deviation in roundness or size
may cause partial overload on
the bearing resulting to
premature failure.
▪ Check drainage holes
▪ Check oil/grease holes
▪ Check bore face condition
→ Rust and any raised edges from scratches, nicks and dents may
prevent correct seating of the outer ring
→ Remove such flaws with an oilstone
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Bearing Fitting
Technique depends on bearing:
•
Size (small, medium, large)
•
Seat (straight bore, tapered bore)
•
Type (separable, non-separable)
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Bearing Installation
Cold mounting
(small size
bearings)
Hot Mounting
(medium to large)
Hydraulic
(medium to large)
Bearing Seat
Cylindrical
Tapered
-Apply light oil on
shaft
-Direct the force on
ring to be mounted
-Heat bearings less Generally not
than 120oC
recommended
-Use gloves to
protect hands
Axial drive-up/
clearance
reduction
Calculation/ mark
final position of
bearing
Check integrity of
hose and viscosity
of mounting fluid
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Correct Cold Mounting
Press Fitting the Inner Ring on Shaft
Press Fitting the Outer Ring into Housing
Simultaneous Press Fitting of both Rings
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Mounting Damage
Incorrect application of mounting force will cause indentation
Axial Brinells
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Hot Mounting
Induction Heating
Oil Bath Method
Temperature < 120oC
Never use Torch!
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Induction Heater
• Most effective heating method
• Fast and easy
• Achieves uniform heating
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Oil Bath Method
Effective heating method
Achieve even heating of inner ring
Disadvantage:
-Requires a lot of work & time
-Internally packed grease may react with oil
Do not use for shielded and sealed bearings.
For safety, use oil with high flash point.
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Dismounting Procedures
•
•
•
•
•
•
•
•
•
Similar precautions during mounting process
Study and prepare the machine carefully
Use appropriate tools
Observe safety at all times
Mark orientation and position of bearing for analysis
Support other components
Follows the reverse order of mounting procedure
More difficult due to large forces involved
Use torch only as last resort
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Dismounting on Shaft
Support the inner ring and apply dismounting force to the shaft
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Dismounting on Housing
Apply force on the outer ring
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Dismounting Tools
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NSK Greases for Rolling Bearings
Applications:
- Agricultural equipment
- Conveyors
- Small electric motors
- Industrial fans
- Pumps
Applications:
- Bearings >100mm shaft size
- Agricultural equipment
- Large electric motors
- Industrial fans
Applications:
- Pulp & paper machineries
- Crushers
- Vibrating screens
- Crane wheels, sheaves
- Heavy machineries
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An interactive learning experience at www.nskacademy.com
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