01. bearing basic knowledge

8/18/2019 01. Bearing Basic Knowledge

1/16

1

July 2012 Bearing Basic KnowledgeSlide 1

Bearing Basic Knowledge

PT Schaeffler Bearings Indonesia


Bearing basic knowledge …

-Bearing types and selection-Bearing internal clearance- Selection of bearing cages-Bearing designation-Bearing tolerance-Shaft and housing tolerances

Training Topics


Fischer

Aktien

Gesellschaft

The Beginning of FAG

The first ever steel ball grindingmachine invented by a Germanengineer in 1883.


Once upon a time…

Introduction to Rolling Bearings


2/16

2


Sliding Friction Rolling Friction




Outer ring

Inner ring

Rollingelement

Cage

Lubricant !!


Bearings whichare non-seperable

Bearings whichare seperable

Bearing Characteristic s


Bearings that can take"dynamic misalignment"

Bearings that can take"static misali gnment"

Bearing Characteristics


3/16

3


Ball

Barrel roller

Tapered roller Cylindrical roller

Needle roller

UnsymmetricalBarrel roller



Line contact(more contact)

Roller Bearings

Higher loadLower speed

Point contact(less contact)

Ball Bearings

Lower loadHigher speed



POINT contact …

Deep groove ball bearing: 6310Dimensions = d x D x B = 50 x 110 x 27Static load rating = C 0 = 38 kNLimiting speed = n G = 14000 rpm

LINE contact …

Cylindrical roller bearing: NU310Dimensions = d x D x B = 50 x 110 x 27Static load rating = C 0 = 113 kNLimiting speed = n G = 6300 rpm



F r

F a

F r F r

F a

"Radial bearings" designedto take the radial force

"Axial bearings" designed

to take the axial force



4/16

4


Contact lineRadial plane

Radial bearing has …the contact angle < 45 degrees

Axial bearing has …the contact angle > 45 degrees


Nominal contact angle is an angle

between the bearing radial plane andthe contact line without any applied load.


Radialball bearings

Radialroller bearings

Axial roller bearings Axial ball bearings



Small misalignmentHigh speed

• Pumps• Shipbuilding• Machine tools• Road vehicles• Railway vehicles• Paper machinery• Power transmission

• Electrical machinery• Conveying equipment• Agricultural machinery• Household appliances• Steelworks and rolling mill• Food and delicacies industry• Mining and construction• Ventilation engineering

Designation 6XXXe.g. 6208, 6310

Deep Groove Ball Bearing


Suffix 2ZShieldGap Seal

Suffix 2RSRSealContact Seal

Prevent dust and dirt Good Good

Prevent water and moisture Bad Good

Applications with outer ring rotating Bad Good

Limiting speed (of the same size) Higher Lower


The sealed bearing is already filled with STANDARD grease


5/16

5


Video !!



• Pumps• Machine tools• Road vehicles• Power transmission• Electrical machinery• Conveying equipment• Ventilation engineering• Steelworks and rolling mill

Small misalignmentHigh speed


Angular Con tac t Bal l Bear ing


O arrangement(Back to Back, DB)

X arrangement(Face to Face, DF)

Tandem arrangement(Tandem, DT)

Ang ular Con tac t Bal l Bear ing




Angular Con tac t Bal l Bear ing


6/16

6


• Paper machinery• Conveying equipment• Agricultural machinery• Ventilation engineering• Mining and construction• Food and delicacies industry

Misalignment 4ºHigh speed

Designation 1XXX, 2XXXe.g. 1207, 2210

Self Alignin g Ball Bearing


No misalignmentHigh speed



Axi al Bal l Bear ing


• Pumps• Crushers• Centrifuges• Machine tools• Road vehicles• Paper machinery• Railway vehicles• Vibrating machinery• Power transmission• Electrical machinery• Conveying equipment• Household appliances• Ventilation engineering• Mining and construction• Steelworks and rolling mill

Designation NXXX, NXXXXe.g. N308, NU328, NU2226

Cylindrical Roller Bearing


SLNU N NUPNJSmall misalignment

Low speedSmall misalignment

Very low speed

Cylindrical Roller Bearing


7/16

7


Needle Roller Bearing

Small misalignmentLow speed

Without rings K…e.g. K20X26X12, K24X30X17

With rings NA…e.g. NA4907, NA6906


Application examples …

Brake pedal Acceleration pedal Automotive gearbox

Needle Roller Bearing


Misalignment 3ºLow speed

• Pumps• Crushers• Shipbuilding• Wind turbines• Road vehicles• Railway vehicles

• Paper machinery• Vibrating screens• Power transmission• Drum belt conveyors• Conveying equipment• Agricultural machinery• Ventilation engineering• Mining and construction• Steelworks and rolling mill

Designation 2XXXXe.g. 23020, 22250

Spherical Roller Bearing


• Pumps• Crushers• Wind turbines• Machine tools

• Road vehicles• Railway vehicles• Power transmission• Conveying equipment• Agricultural machinery• Tunnel boring machinery• Steelworks and rolling mill

Small MisalignmentLow speed


Tapered Roller Bearing


8/16

8




Tapered Roller Bearing


No misalignmentLow speed


Axi al Cyl indri cal Ro ll er Bear ing


• Extruders

• Gearboxes• Generators• Palm oil mills• Paper machines• Boats and ships

Misalignment 3ºLow speed


Axi al Sph eri cal Ro ll er Bear ing


Bearing Selection


9/16

9


Radial clearance Axial clearance

C2CNC3C4C5

S r

S a

Bearing Internal Clearance


D

d

ST

Internal clearance is for…

1. Expansion and contraction of the inner and outer r ing due totight fits.

2. Thermal expansion from heatgenerated during operation, butthe key valueis the temperaturedi ff erence between the inner and outer ring, not how high thetemperature.

- Clearance before mounting

- Clearance after mounting

- Operating clearance



C1 Clearance smaller than C2C2 Clearance smaller than CNCN Clearance normal (no suffix)

C3 Clearance bigger than CNC4 Clearance bigger than C3C5 Clearance bigger than C4

Clearance class specified by following suffixes …

Example: 6205 (CN), 6309-C3, NU230-E-M1-C4

If the recommended shaft and housing tolerances are fulfilled.The normal operating clearance is achieved with clearance

CN, in larger bearings, predominantly with C3.



Example: Bearing 6310 has internal clearance 6-23 microns

Bearing 6310-C3 has internal clearance 18-36 microns

See HR1 page 215



10/16

10


6309-2Z used to replace 6309-2Z-C3 in an e-motor, jammed in 1 month.

- Insufficient operating clearance results in hot running and seizing

- Excessive operating cl earance results in high vibration / low accuracy.



0+

Temperature Difference

Tight Fits

CN / C3 / C4



Tolerance class specified by following suffixes …

Example: 6208 (PN), 7310-P5, 6309-P63 etc.

For an application which requireshigh accuracy or very high speed

Tolerances of Standard Bearings

PN Precision Normal (no suffix)

P6 Precision better than PNP5 Precision better than P6

P4 Precision better than P5

P2 Precision better than P4


Example:Inner diameter of 6220 is between 99.980 - 100.000 mmInner diameter of 6220-P6 is between 99.985 - 100.000 mm

From HR1 page 122Tolerance class PN

From HR1 page 124Tolerance class P6

Tolerances of Standard Bearings


11/16

11


Cage functions-To separate rolling elements-To keep a pitch between rolling elements-To hold rolling elements within a bearing-To guide rolling elements to the raceway

Cage - Functions


Cage - Guidance

Rolling element guide

(no additional suffix)Normal applications

Inner ring guide

(with suffix B)High vibration

High speed

Outer ring guide

(with suffix A)High vibration

High speed


Window typed cage for anangular contact ball bearing

Window typed cage fora cylindrical roller bearing

Cage - Moulded Plastic Cage (Polyamide)


Ribbon type cagefor a ball bearing

Riveted cagefor a ball bearing

Window typed cagefor an spherical

roller bearing

Cage - Pressed Steel Cage


12/16

12


Riveted cagefor a ball bearing

Window typed cagefor a ball bearing

Riveted cagefor a cylindricalroller bearing

Cage - Machined Brass Cage


Criterion Steel Brass Polyamide

Weight Good Bad Very Good

Strength Very Good Very Good Good

Cost / Price Good Bad Good

Space for lubricant Very Good Good Good

Running noise Good Good Very Good

Corosion fromchemical / lubricant

Very Good Good Bad

Temperature morethan 120 degrees C

Good Good Bad

Cage – Selection

1. The plastic cage has its own advantages for weight, noise, and flexibility2. Strength comparison between two metallic cages i.e. steel and br ass cage3. Brass cage has emergency running behavior, easy to machine with accuracy4. New bearings are with pressed steel cage, machined brass cage is expensive


DGBB OD240 mm is dimensionally stable up to 200 degrees

ACBB OD240 mm is dimensionally stable up to 200 degrees

SABB every sizes is dimensionally stable up to 150 degrees

Bearing with a plastic cage (polyamide) can stand up to 120 degreesBearing with rubber seal and standard grease can stand up to 100 degrees

Maximum Operating Temperature

Max operating temperature of standard BALL bearings …


CRB every sizes is dimensionally stable up to 120 degreesSRB every sizes is dimensionally stable up to 200 degreesTRB every sizes is dimensionally stable up to 120 degreesNRB every sizes is dimensionally stable up to 120 degrees

Max operating temperature of standard ROLLER bearings …

Bearing with a plastic cage (polyamide) can stand up to 120 degreesBearing with rubber seal and standard grease can stand up to 100 degrees

Maximum Operating Temperature


13/16

13


Bearing designation can tell you …

1. Bearing type2. Dimensions3. Part tolerances4. Bearing clearance5. Cage design and material6. Other special characteristics

Bearing Designation


Bearing designation

Prefix SuffixBase designation

Bearingtype

Widthseries

Diameter series

Borecode

Bearing Designation


The first digit specify the bearing type …

1XXX Self aligning ball bearing2XXXX Spherical roller bearing3XXXX Tapered roller bearing5XXXX Axial ball bearing6XXX Deep groove ball bearing7XXX Angular contact ball bearing8XXXX Axial cylindrical roller bearingNXXXX Cylindrical roller bearing

Bearing Designation


The last one or two digits is the bore code

Bore code

3 to 90001020304...96/500/530

Bore diameter

3 to 9 mm10 mm12 mm15 mm17 mm20 mm...480 mm500 mm530 mm

Bore code X5

Bearing Designation


14/16

14


One or two digits in the middle are width and diameter series

00

0 1 2 3 4 0 1 2 3 0 1 2 3 0 2

2404332313033222120240302010 Wi dt h s er ies Wi dt h s er ies Wi dt h s er ie s Wi dt h s eri es

Dim. series Dim. series Dim. series Dim. series

02

34

Bearing Designation

Example:Spherical roller bearing with designation 23220 is WIDER than 22220Spherical roller bearing with designation 22320 is BIGGER than 22220


62066 = Deep groove ball bearing

(0) = Width series 02 = Diameter series 206 = 06 x 5 = 30 mm bore

7305-B7 = Angular contact ball bearing(0) = Width series 03 = Diameter series 305 = 05 x 5 = 25 mm bore

Bearing Designation


30209-A3 = Tapered roller bearing0 = Width series 02 = Diameter series 2

09 = 09 x 5 = 45 mm bore

NU2314-ENU = Cylindrical roller bearing2 = Width series 23 = Diameter series 314 = 14 x 5 = 70 mm bore

Bearing Designation


See HR1 page 148

One bearing has 2 ringsinner and outer ring.

There are 2 load cases,circumferential load andpoint load.

Shaft and Housin g Tolerances


15/16

15


Inner ring rotates

Outer ring stationaryLoad direction constant

IR - Circumferential load(tight fit necessary)

OR - Point l oad(loose fit permissible)

Example:Shaft weightRoll pressSee HR1 page 148

Shaft and Housin g TolerancesSchematic 1



Inner ring stationaryOuter ring rotatesLoad direction constant

IR - Point load(loose fit permissible)

OR -Circumferential load(tight fit necessary)

ExampleCar hub bearing

See HR1 page 148



Inner ring rotatesOuter ring stationaryLoad direction rotates

IR - Point load(loose fit permissible)

OR - Circumferential load(tight fit necessary)

ExampleCentrifugesVibrating screensSee HR1 page 148



Inner ring stationaryOuter ring rotatesLoad direction rotates

IR - Circumferential load(tight fit necessary)

OR - Point l oad(loose fit permissible)

ExampleHub bearing with unbalanceSee HR1 page 148


16/16

16


See HR1 page 149

Shaft and Housing Tolerances

- Meaning of tight fit- Meaning of loose fit- Meaning of transition fit- Difference betweencapital and small letter


Example: 6212 in e-motor, recommended shaft fit is 60 k6

From HR1 page 150 …



From HR1 page 155 …

Example: shaft fit 60 k6, shaft tolerance is +2 / +21 i.e. 60.002 – 60.021 mm



" Thank you for you r attention "

PT Schaeffler Bearings IndonesiaGedung Graha Pena Suite 707Jl. A Yani no 88Surabaya - 60234Phone : 0318270030Fax : 0318270030

01. bearing basic knowledge

Documents