Home > Leading Products > Thin Section Bearings

Thin Section Bearings

Static equivalent load
The static equirvalent load is a hypothetical load which would cause the same total permanent deformation at the most heavity stressed contact point between the rolling elements and the raceway as under actual load conditions;that is when both static radial loads and static axial loads are simultaneously applied to the bearing.
For radial bearings this hypothetical load refers to pure radial loads,and for thrust bearings it refers to pure centric axial loads.These loads are designated static equivalent radial loads and static equivalent axial loads respectively.
 
Static equivalent radial load
For radial bearings the static equirvalent radial load can be found. The greater of the two resultant values is always taken for Por
    Por=XoFr+YoFa
    Por=Fr
Where,
    Por: Static equivalent radial load N
    Fr: Actual radial load N
    Fa: Actual axial load N
    Xo: Static radial load factor
    Yo: Static axial load factor
The values for Xo and Yo are given in the respective bearing tables.
 
Static equivalent axial load
For spherical thrust roller bearings the static equivalent axial load is expressed by formula
    Poa=Fa+2.7Fr
where,
Poa: Static equivalent axial load N
Fr: Actual radial load N
Fa: Actual axial load N
Provided that Fr/Fa÷0.55 only
 
Bearing Tolerances
Bearing "tolerances"or dimensional accuracy and running accuracy, are regulated by ISO and JIS standards.For dimensional accuracy,these standards prescribe the tolerances necessary when installing bearings on shafts or in housings.Running accuracy is defined as the allowable limits for bearing runout during operation.
Dimensionsal accuracy constitutes the acceptable values for bore diameter,outer diameter,assembled bearing width,and bore diameter uniformity as seen in chamfer dimensions,allowable inner ring tapered bore deviation and shape error. The geometry accuracy are average bore diameter variation,outer diameter variation,average outer diameter unevenness,as well as raceway width and height variation(for thrust bearings).
Running accuracy constitutes the acceptable values for inner and outer ring radial runout axial runout,inner ring side runout.and perpendicularity of outside diameter surface.
 
Comparison of tolerance classifications of national standards
Standard

Applicable
Standard

 Tolerance Class Bearing Types
Chinese Industrial Standard（GB） GB 307.1 P0 P6 P5 P4 P2 All types

International
Organization
for Standardization(ISO)

 ISO 492 Class 6x Class 6 Class 5 Class 4   Radial bearings
ISO 199 Normal class Class 6 Class 5 Class 4   Thrust ball bearings
ISO 1224     Class 5A Class 4A   Precision instrument bearings
Deutsches institut for Normung(DIN) DIN 620 P0 P6 P5 P4 P2 All types
 
Bearing internal clearance
Bearing internal clearance is the amount of internal free movement before mounting,when either the inner ring or the outer ring is fixed and the other ring is free to move.displacement can take place in either an axial or radial direction. This amount of displacement (radially or axially) is termed the internal clearance and, depending on the direction, is called the radial internal clearance or the axial internal clearance.
   
Criteria for selecting bearing internal clearance
A bearing's life is theoretically maximum when operating clearance is slightly negative at steady operation. In reality it is however difficult to constantly maintain this optimal condition.If the negative clearance becomes enlarged by fluctuating operating conditions,heat will be produced and life will decrease dramatically. Under ordinary circumstances you should therefore select an initial internal clearance where the operating clearance is slightly larger than zero.
For ordinary operating conditions,use fitting for ordinary loads.If rotational speed and operating temperature are ordinary,selecting normal clearance enables you to obtain the proper operating clearance.
Radial internal clearance of deep groove ball bearings
Unit:µm
Nominal bore diameter C2 CN C3 C4 C5
d mm
over incl.		 min max min max min max min max min max
10 18 0 9 3 18 11 25 18 33 25 45
18 24 0 10 5 20 13 28 20 36 28 48
24 30 1 11 5 20 13 28 23 41 30 53
30 40 1 11 6 20 15 33 28 46 40 64
40 50 1 11 6 23 18 36 30 51 45 73
50 65 1 15 8 28 23 43 38 61 55 90
65 80 1 15 10 30 25 51 46 71 65 105
80 100 1 18 12 36 30 58 53 84 75 120
100 120 2 20 15 41 36 68 61 97 90 140
120 140 2 23 18 48 41 81 71 114 105 160
140 160 2 23 18 53 46 91 81 130 120 180
160 180 2 25 20 61 53 102 91 147 135 200
180 200 2 30 25 71 63 117 107 163 150 230
200 225 2 35 25 85 75 140 125 195 175 265
225 250 2 40 30 95 85 160 145 225 205 300
280 315 2 55 40 115 100 190 175 270 245 370
315 355 3 60 45 125 110 210 195 300 275 410
400 450 3 80 60 170 150 270 250 380 350 510
450 500 3 90 70 190 170 300 280 420 390 570
500 560 10 100 80 210 190 330 310 470 440 630
560 630 10 110 90 230 210 360 340 520 490 690
 
Radial internal clearance for duplex angular contact ball bearings
Unit：µm
Nominal bore Diameter C2 CN C3 C4 C5
d mm
over incl.		 min max min max min max min max min max
10 18 3 8 6 12 8 15 15 24 30 40
18 30 3 10 6 12 10 20 20 32 40 55
30 50 3 10 8 14 14 25 25 40 55 75
50 80 3 11 11 17 17 32 32 50 75 95
80 100 3 13 13 22 22 40 40 60 95 120
100 120 3 15 15 30 30 50 50 75 110 140
120 150 30 16 16 35 35 55 55 80 130 170
150 180 3 18 18 35 35 60 60 90 150 200
180 200 3 20 20 40 40 65 65 100 180 240


 

Note: The clearance group in the table is applied only to contact angles in the table below
Contact angle Nomial Contact Applicable clearance group
Symbol angle          
C 15° C1 C2      
A 30°   C2 CN C3  
B 40°     CN C3 C4


 

Axial internal clearance of four points contact ball bearings Unit：µm
Nominal bore Diameter C2 CN C3 C4

d mm
over incl.

 min max min max min max min max
17 40 26 66 56 106 96 146 136 186
40 60 36 86 76 126 116 166 156 206
60 80 46 96 86 136 126 176 166 226
80 100 56 106 96 156 136 196 186 246
100 140 66 126 116 176 156 216 206 266
140 180 76 156 136 196 176 236 226 296
180 220 96 176 156 216 196 256 246 316
 
Lubrication:
The purpose of bearing lubrication is to prevent direct metallic contact between the various rolling and sliding elements. This is accomplished through the formation of a thin oil (or grease) film on the contact surfaces. However,for rolling bearings,lubrication has the following:
(1) Reduction of friction and wear
(2) Dissipation of friction heat
(3) Prolonged bearing life
(4) Prevention of rust
(5) Protection against harmful elements
In order to exhibit these effects,a lubrication method that matches service conditions. In addition to this,a quality lubricant must be selected,the proper amount of lubricant must be used and the bearing must be designed to prevent foreign matter from getting in or lubricant from leaking out.
 
External bearing sealing devices
External seals have two main functions:to prevent lubricating oil from leaking out,and,to prevent dust,water,and other contaminants from entering the bearing.When selecting a seal,the following factors need to be taken into consideration:the type of lubricant (oil or grease),seal peripheral speed,shaft fitting errors,space limitations,seal friction and resultant heat increase, and cost.
Sealing devices for rolling bearings fall into two main classifications:non-contact seals and contact seals.
 
Raceway and rolling materials
While the contact surfaces of a bearing's raceways and rolling elements are subjected to repeated heavy stress,they still must maintain high precision and rotational accuracy. To accomplish this. the raceways and rolling elements must be made of a material that has high hardness, is resistant to rolling fatigue, is wear resistant, and has good dimensional stability. The most common cause of fatigue in bearings is the inclusion includeing hard oxides that can cause fatigue crack.Clean steel with minimal non-metallic inclusion must therefore be used.
First Prev. 2 of 2 Next Last