SKF angular contact ball bearings – your key to longer - Prema

44 Pages·2002·1.37 MB·English

SKF angular contact ball bearings
– your key to longer service life
Contents
Made by SKF® stands for excellence. It symbolises 1Product information ................................................. 3
our consistent endeavour to achieve total quality in Diversity and quality .................................................... 3
everything we do. For those who use our products. Why specify angular contact ball bearings? .............. 3
“Made by SKF” implies three main benefits. Why specify SKF angular contact ball bearings? ....... 3
Advantages by design with
Reliability– thanks to modern, efficient products, SKF Explorer bearings ................................................ 4
based on our worldwide application know-how, optim- Technical improvements ............................................. 4
ised materials, forward-looking designs and the most Identification symbols................................................. 5
advanced production techniques. Advantages for your design:
higher performance with Explorer bearings ............. 6
Cost effectiveness– resulting from the favourable Longer service life ...................................................... 6
ratio between our product quality plus service facilities, New designs with smaller bearings ............................ 7
and the purchase price of the product. New designs with higher power density..................... 7
Efficient in all industrial segments ............................. 8
Market lead – which you can achieve by taking
advantage of our products and services. Increased
operating time and reduced down-time, as well as 2Recommendations ...................................................10
improved output and product quality are the key to Selection of bearing size.............................................10
a successful partnership. Bearing life ..................................................................10
Load carrying capacity of paired
single row bearings ....................................................11
Equivalent dynamic bearing load ...............................12
Equivalent static bearing load ....................................12
Minimum load .............................................................12
Determining axial force for bearings
mounted singly or paired in tandem ...........................13
Design of bearing arrangements ...............................14
Mounting and dismounting .........................................16
Mounting ....................................................................16
Dismounting ...............................................................17
Service for a lasting partnership ................................18
3Product data .............................................................19
Single row angular contact ball bearings ..................19
General bearing data ..................................................19
Assortment .................................................................22
Product table ..............................................................24
Double row angular contact ball bearings ................30
General bearing data ......................................................30
Assortment ..................................................................34
Product table ...............................................................36
Other SKF angular contact ball bearings ..................40
The SKF Group – a worldwide organisation ..............42
2
1Product information 2Recommendations 3Product data
Customer benefits Page ............. 10 Page ............. 19
Diversity and quality
1
Why specify angular
angular contact ball bearings offer a Universal matching
contact ball bearings? completely new level of performance. At SKF, universally matchable single
With SKF angular contact ball bearings, row angular contact ball bearings are
High rotating speeds, combined radial you benefit in a number of ways: standard. These bearings simplify
and axial loads, a high degree of stiff- assembly and can also increase the
ness and running accuracy – these are High performance quality of your products. Our selection
the application requirements where They have a high load carrying capacity of clearance and preload classes
angular contact ball bearings excell. and thus allowing smaller bearings to covers all possible application require-
The great variety of applications and be used while still providing long ser- ments.
operating conditions calls for unique vice life.
bearing solutions made possible by Integral sealing solutions
a wide range of angular contact ball Quieter and cooler running Double row angular contact ball bear-
bearings. With their optimal internal geometry, ings are available with integral seals
they run quieter and cooler and can and shields. These bearings are sup-
provide longer maintenance intervals. plied with grease and do not require
Why specify SKF angular
maintenance.
contact ball bearings? Precise shaft guidance
Due to precision manufacturing pro- Standard solutions
Because SKF is your reliable, expert cesses, almost all SKF angular con- It will be hard to find an application for
source for angular contact ball bear- tacts meet lower tolerances, to enable which there’s no standard SKF bearing
ings. Because SKF has a wide range a smoother, truer running shaft with readily available from our vast selection
of types and variants unmatched any- less heat and less vibration. and enormous variety.
where else. Because when you work
with SKF you don’t have to settle for High temperature capability Customer satisfaction
any unfavourable compromises. Since They can withstand relatively high Now you can build additional value into
the introduction of the BE bearings in operating temperatures without signi- your products with SKF Explorer bear-
1984, SKF single row angular contact ficant loss of dimensional stability. ings. Your customers will definitely be
ball bearings have set the standard. impressed by the low operating costs,
Since then, time certainly hasn’t stood reliability and long service life of your
still, and neither has SKF. machines – no doubt in part to your use
The best example: our Explorer of SKF bearings.
design single row and double row
3
1Product information 2Recommendations 3Product data
New design Page ............. 10 Page ............. 19
Advantages by design with
SKF Explorer bearings
At SKF we’re continuously working to Diagram 1
improve the performance and durabil-
m
ity of our products. And with the new
m 0,015
Explorer series angular contact ball e, Explorer 7307 BECB set
bearings, we think you’ll notice the dif- nc 0,010 Standard 7307 BECB set
a
ference immediately. These bearings ar 0,005
e
can provide: Cl
0
m Explorer 3310 A/C3
• Even longer service life, m -0,005 Standard 3310 A/C3
• Even higher reliability, ad, -0,010 Explorer 7307 BEGA set
• Even more performance. elo Standard 7307 BEGA set
Pr -0,015
The following pages will describe the -0,020
improvements we have made to our
10 100 1000 10000
angular contact ball bearings in the
Operating hours
72 and 73 series and in the 32 and
33 series (52/53 series US).
Examples:7307 BE set, Fa/Fr= 1,23, C/P = 29, operating temperature 110 °C (230 °F)
3310 A/C3, Fa/Fr= 1,23, C/P = 19, operating temperature 80 °C (175 °F)
Technical improvements
Change of the residual axial bearing clearance/preload during operation
Improved materials
Explorer angular contact ball bearings
are manufactured from an extremely
high quality bearing steel with a very
low oxygen content and a minimum More precise shaft guidance
number of impurities. The rings are Explorer single row bearings are manu-
manufactured from forged or cold factured to P5 running accuracy.
rolled blanks. Explorer double row bearings are
All rings are heat treated to provide manufactured to P6 running accuracy.
dimensional stability up to 150 °C
(300 °F). The advantage: SKF single Better ball quality
row angular contact ball bearing sets The balls used in Explorer angular
hold their original buildt-in clearances contact ball bearings are one ISO
and preloads for extended operating grade better than before. The more
times (➔ diagram 1 ). uniform ball diameter helps to
improve running accuracy even
Improved inner geometry at high speeds, while reducing
Computer-aided design and manufac- noise and operating tempera-
turing programs permit almost unde- ture.
tectable geometrical changes in the
bearing. These small but effective New cages
changes in the bearing’s geometry Explorer single row bearings have
lead to measurable improvements in solid cages made from polyamide or
performance and service life. One brass. Polyamide cages have been
effect of this fine tuning: Explorer improved to better withstand high
angular contact ball bearings are less accelerations. Brass cages are manu-
sensitive to potential axial overloading. factured to closer tolerances and have
4
1Product information 2Recommendations 3Product data
New design Page ............. 10 Page ............. 19
Fig 1 been improved to provide better ball
Explorer angular contact ball
guidance and maximize the effects of 1
bearings
the lubricant under all operating condi-
tions.
• Improved materials
Explorer double row bearings are
• Optimised internal geometry
available as standard with a newly-
• Higher precision
developed crown cage made of sheet
• Higher ball quality
steel.
• Improved cages
• Single bearings which can be
Effective seals
paired universally
Double row angular contact ball bear-
• New shields for double row
ings are available with seals or shields.
bearings
Shielded Explorer bearings (➔ fig 1 )
use a new shield design. A new simple
labyrinth keeps contaminants out and
Shielded Explorer double row angular
retains grease in the bearing cavity.
contact ball bearing
Identification symbols
Explorer angular contact ball bearings Packaging
are not an extension of the assort- Explorer bearings come in a unique
ment. They replace final variants of package, so that they can be recog-
the previous types. And because it is nised immediately as Explorer bearings.
easier for inventory management,
their part numbers remain the same. Laser inscription
Nevertheless, Explorer bearings can A new feature of the Explorer bearings
be recognised easily. is their laser inscription. It is not only
more legible, but also more environ-
mentally friendly because acids are no
longer required for etching. It also per-
mits individual markings. Depending
on the requirements in Quality Assur-
ance, the bearings can be traced
precisely.
5
1Product information 2Recommendations 3Product data
New performance class Page ............. 10 Page ............. 19
Advantages for your design: higher
performance with Explorer bearings
The technical improvements incorp- life and decreased maintenance costs ball bearings (➔ fig 1 ). With the exist-
orated in Explorer angular contact for your application. ing design, the axial bearing of the
ball bearings can provide one of four drive shaft is the critical point. The cal-
general design benefits. For existing culated life of this bearing arrange-
Longer service life
designs, you can either increase ser- ment, consisting of three 7308 BEGAP
vice life or increase power output. For bearings amounts to 50 900 hours;
new designs, you can maintain power The extended life of Explorer angular calculated in accordance with the SKF
output or increase power density. The contact ball bearings can be demon- Life Method. With new Explorer bear-
option you chose depends on the cus- strated best with the use of an ex- ings, the calculated life amounts to
tomer and the application’s require- ample. The shafts of a twin screw com- 96 200 hours. This means a life 1,9
ments. Whichever option you chose, pressor are supported radially with times longer under otherwise identical
new Explorer angular contact ball cylindrical roller bearings and axially conditions and without any changes in
bearings will provide increased service with a matched set of angular contact the design.
Increase service life of existing Maintain power output of new
designs designs
Don’t need to increase power output? Use an Use a smaller Explorer bearing to:
Explorer bearing of equal size to:
• Reduce overall dimensions to save
• Increase the reliability on material cost and weight
• Reduce vibration • Reduce heat generation
• Reduce heat generation • Increase speeds
• Increase service intervals
• Increase machine uptime
Increase power Increase power
output of density of new
existing designs designs
Avoid costly redesign by using an Use a lower cross section
Explorer bearing of equal size to: Explorer bearing with the same
outside diameter to:
• Increase power density (output)
• Increase speeds • Increase shaft size
• Increase loads • Achieve a stiffer design
• Operate at the same or higher speeds
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1Product information 2Recommendations 3Product data
New performance class Page ............. 10 Page ............. 19
New designs with
Table 1
smaller bearings Standard Explorer Cross section Benefit life 1
bearing bearing A L
Expl ×100 10m,Expl
A L
In many cases where 73 series bear- std 10m,std
ings are used, it will be possible to
use 72 series bearings in the future.
Same bore 7306 BE 7206 BE 64 % 1
Even with a smaller bearing, a longer diameter
bearing service life will be possible.
Table 1 shows some suitable
examples. 7308 BE 7208 BE 63 % 1,2
Without changes to the shaft,
bearing arrangements can also be
designed more compactly. Explorer 7319 BE
7219 BE 51 % 1,1
bearings permit lighter structures with
the same capacity.
New designs with higher
Same outer 7304 BE 7205 BE 84 % 1,7
power density diameter
If the outside diameter of the bearing
7308 BE 7210 BE 70 % 1,6
remains unchanged, the transition
from 73 series bearings to 72 series
bearings will permit the use of
stronger shafts (➔ table 1 ). 7313 BE 7216 BE 63 % 1,5
With otherwise unchanged parts,
more rigid designs with higher power
density are possible. And the service
life of the bearing will be increased
significantly.
Comparison of Explorer and standard design bearings – possible downsizing
Twin-screw compressor bearing arrangement
Fig 1
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1Product information 2Recommendations 3Product data
Application examples Page ............. 10 Page ............. 19
Efficient in all industrial
segments
Lower friction, quieter running and, used in both pumps and compressors
above all, improved reliability in com- must be able to accommodate com-
plex applications with combined loads bined axial and radial loads, high
make SKF angular contact ball bear- speeds, poor lubrication and con-
ings indispensable in many areas. taminated conditions.
Long service life and reliable perform- The improvements made to the new
ance have earned SKF angular con- Explorer bearings were aimed primari-
tact ball bearings an excellent reputa- ly at the demanding requirements of
tion in a variety of industries ranging both pumps and compressors. For
from gearboxes to turbines. these applications a recommended
Nevertheless, the most common product range is available. Additional
applications for angular contact ball information can be found in publica-
bearings are pumps and compressors. tion 4782 “Recommended Product
These applications are not just the Range: SKF angular contact ball
most common, they are also the most bearings for pumps and compressors”.
demanding. For example, the bearings
Industrial segments Requirements Solution
•Fluid machinery: •Long service life
Pumps, compressors, blowers, •High load-carrying capacity and
ventilators, turbines high speeds
•Automotive engineering: •High degree of stiffness
Drives, clutches, gearboxes, •High degree of running accuracy
wheel bearings, components •Low heat generation
•Industrial drives and drive •Quiet running
motors •Technical support
•Printing machines
•Textile machines
•Material handling
1Product information 2Recommendations 3Product data
Application examples Page ............. 10 Page ............. 19
1
1Product information 2Recommendations 3Product data
Page ............. 3 Bearing size Page ............. 19
Selection of bearing size
Bearing life
Bearing life can be calculated easily account the complex relationships
using the programs found in the between different factors influencing
The life-extending improvements, “SKF Interactive Engineering Cata- bearing life. These factors have been
embodied in SKF Explorer bearings logue”. Explorer bearing data will be simplified so that they can be inserted
can best be understood using the added to the online version at into your calculations. Diagram 1
SKF Life Method. This life calculation www.skf.com contains the life modification factor for
method constitutes an extension of standard SKF angular contact ball
the fatigue life theory developed by Life modification factor aSKF bearing designs. Diagram 2 contains
Lundberg and Palmgren and is better The SKF Life Method takes into the values for Explorer bearings. The
able to predict bearing life. The life
method, first presented by SKF in
1989 is standardised today in ISO
281:1990/ Amd.2:2000. The modified
rating life for angular contact ball bear- Life modification factor a for standard design angular contact ball bearings
SKF
ings can be calculated from
Diagram 1
L = a a L
10m 1 SKF 10
50
or
a
SKF
(C)3 20
L = a a
10m 1 SKF
P
10
With a constant rotational speed, the
life in operating hours can be calculat-
ed from the following formula: 5 4
= 2
κ 1 8
0,
1 000 000 (C)3 0,6
L10mh= a1aSKF 60 n P 2 0,5
4
0,
where 1 0,3
L = modified rating life, millions of
10m
revolutions 0,5 0,2
L = modified rating life, operating
10mh
hours 0,1 5
L = basic rating life, millions of
10
0,2
revolutions
a = life adjustment factor for
1
reliability (for 90 % reliability 0,1 κ=0,1
a = 1, according to ISO 281)
1
a = life modification factor based
SKF
on the SKF Life Method, 0,05
(➔ diagrams 1 and 2 ) 0,005 0,010,02 0,05 0,1 0,2 0,5 1 2 η Pu5
C = basic dynamic load rating, N c P
P = equivalent dynamic bearing
load, N If κ> 4, use κ= 4 curve
As the value of ηc (Pu/P)tends to zero, aSKFtends to 0,1 for all values ofκ
n = rotational speed, r/min
10