Super-precision angular contact ball bearings

48 Pages·2016·1.77 MB·English

Super-precision angular
contact ball bearings:
High-capacity
72 .. D (E 200) series
Contents
A Product information C Product data
SKF high-capacity super-precision Bearing data – general ............ 18
angular contact ball bearings ...... 3 Boundary dimensions ............. 18
Chamfer dimensions. . . . . . . . . . . . . . . 18
An extended range – a growing Tolerances ...................... 18
assortment ..................... 4 Bearing preload .................. 18
Bearing design ................... 5 Bearing axial stiffness. . . . . . . . . . . . . . 22
Bearing series ................... 6 Fitting and clamping of bearing rings .. 24
Bearing variants .................. 6 Load carrying capacity of bearing sets . 25
Single bearings and matched Equivalent bearing loads ........... 26
bearing sets ..................... 7 Attainable speeds ................. 26
Cages .......................... 26
Applications .................... 8 Seals .......................... 27
Materials ....................... 27
Heat treatment ................... 27
B Recommendations Marking of bearings and bearing sets .. 28
Packaging ....................... 29
Bearing arrangement design ....... 10 Designation system ............... 29
Single bearings. . . . . . . . . . . . . . . . . . . 10
Bearing sets ..................... 10 Product tables .................. 32
Type of arrangement .............. 11
Application examples .............. 12
D Additional information
Lubrication ..................... 14
Grease lubrication for open bearings .. 14 Setting the highest standard for
Sealed bearings .................. 15 precision bearings ............... 42
Running-in of open and sealed, Super-precision angular contact ball
grease lubricated bearings .......... 15 bearings ........................ 42
Oil lubrication for open bearings ...... 16 Super-precision cylindrical roller
bearings ........................ 43
Super-precision double direction angular
contact thrust ball bearings ......... 43
Super-precision angular contact thrust
ball bearings for screw drives ........ 43
Super-precision axial-radial cylindrical
roller bearings ................... 43
SKF – the knowledge engineering
company ....................... 46
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SKF high-capacity
A
super-precision angular
contact ball bearings
Machine tools and other precision applica- SKF bearings in the 72 .. D (E 200) series
tions require superior bearing performance. are characterized by:
In these applications, high system rigidity is
one of the main performance challenges, as • high load carrying capacity
the magnitude of elastic deformation under • high degree of stiffness
load determines the productivity and accur- • extended bearing service life
acy of the equipment. Parallel Kinematic • low heat generation
Machines (PKM), for example, are known for • low noise and vibration levels
their ability to provide high structural rigidity
and high dynamic capacities. But this is only The bearings provide high reliability and
possible when the bearings inside these superior accuracy for applications such as
machines step up to the challenge. SKF has Parallel Kinematic Machines (PKM), lathe
developed a new generation of super-preci- spindles, grinding and boring machines,
sion angular contact ball bearings that can high-speed dynamometers and
meet these ever-increasing performance turbochargers.
requirements. The ability of the new design
super-precision angular contact ball bear-
ings in the 72 .. D (E 200)1) series to accom-
modate heavy loads, and still provide a high
degree of rigidity, makes them an excellent
solution for these and similar applications.
1) Where applicable, designations in parentheses and italics refer to the corresponding SNFA equivalent.
3
An extended range
– a growing assortment
The growing SKF assortment of super- To accommodate the diverse operating Bearings in the 72 .. D (E 200) series, like
precision bearings is now complemented by requirements of precision applications, all angular contact ball bearings, are nearly
angular contact ball bearings in the 72 .. D bearings in the 72 .. D (E 200) series are always adjusted against a second bearing to
(E 200) series. The extended range of bear- manufactured to two tolerance classes and balance the counterforces. To accommodate
ings in this series now accommodates shaft with two contact angles. Those suitable for heavier loads and axial loads in both direc-
diameters ranging from 7 to 140 mm. And, universal matching or mounting in sets are tions, the bearings are used in sets consist-
there is also a relubrication-free, sealed produced to four preload classes, to meet ing typically of up to four bearings.
bearing series, available on request. almost all application requirements in terms
of speed and rigidity. Matched bearing sets
with a special preload can be supplied on
request. For many sizes, the bearings are
available, standard, with a choice of two ball
materials. The most common sizes have a
polyetheretherketone (PEEK) cage to
accommodate extended operating
temperatures.
SKF super-precision angular contact ball bearings: 72 .. D (E 200) series
Features Benefits
• High number of large balls • High load carrying capacity, high degree of rigidity
• Optimized chamfer design • Facilitated mounting
• ISO dimension series 02 • Large cross section, robust
• Asymmetrical outer ring • Accommodates radial loads, and axial loads in one direction
• Lightweight cage (phenolic resin or PEEK) • Low friction, good lubricant supply to ball/raceway contact areas
• High-temperature PEEK cage, for most common sizes • Accommodates operating temperatures up to 150 °C
• High-speed grease, for sealed variant • High-speed capability, relubrication-free, good thermal stability
• Non-contact seals, for sealed variant • High-speed capability, prevents entry of contaminants, extended
bearing service life
4
Bearing design
The design of the symmetrical inner ring
and asymmetrical outer ring enables the A
SKF super-precision single row angular bearings to accommodate radial loads, and
contact ball bearings in the 72 .. D (E 200) axial loads in one direction. When compared
series are designed to accommodate heavy to other precision angular contact ball bear-
loads at relatively high speeds under low to ings, D design bearings have a high number
moderate operating temperatures. of large balls to provide the highest possible
Features of D design bearings include, load carrying capacity. The bearings have an
among others: outer ring shoulder-guided cage made of
either fabric reinforced phenolic resin or
• a symmetrical inner ring carbon fibre reinforced polyetherether-
• an asymmetrical outer ring ketone (PEEK). Both cage types are
• a high number of large balls designed to enable good lubricant supply to
• a lightweight cage, outer ring the ball/raceway contact areas. The shape of
shoulder-guided the chamfers of the inner and outer rings is
D design bearings have a high number of large
• an optimized chamfer design optimized for improved mounting accuracy.
balls to accommodate heavy loads.
As a result, mounting is not only facilitated,
but there is also less risk of damage to asso-
ciated components.
a°
r ,r
1 3
b°
r ,r
2 4
Optimized design of bearing ring chamfers to
facilitate mounting.
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Bearing series Bearing variants Contact angles
Standard bearings are manufactured with
Bearings in the 72 .. D (E 200) series are The many variants of SKF bearings in the the following contact angles:
based on the ISO diameter series 2 and 72 .. D (E 200) series are well suited to
width series 0. Bearings in the 72 series are accommodate various operating conditions • a 15° contact angle, designation suffix CD (1)
more robust and have the largest cross sec- with regard to load, speed and rigidity. • a 25° contact angle, designation suffix
tion for a given bore diameter, compared to ACD (3)
bearings in the 718, 719 and 70 series.
With two contact angles to choose from,
designers can optimize their application
based on axial load, speed and rigidity
requirements. A larger contact angle pro-
vides a higher degree of axial stiffness and a
higher axial load carrying capacity. Speed
capability is subsequently reduced.
Bearings in the 72 series are more robust and have the largest cross section for a given bore Two contact angles to accommodate different
diameter, compared to bearings in other series. axial load, speed and rigidity requirements.
15° 25°
72
70
719
718
6
Ball materials Sealed bearings Single bearings and
Bearings with a bore diameter up to 85 mm Bearings with a bore diameter ranging from matched bearing sets A
are available, standard, with: 10 to 80 mm can be supplied with an inte-
gral seal fitted on both sides and filled with Bearings in the 72 .. D (E 200) series are
• steel balls, no designation suffix premium grease. The seal forms an available, standard, as:
• ceramic (bearing grade silicon nitride) extremely narrow gap with the cylindrical
balls, designation suffix HC (/NS) surface of the inner ring shoulder. • single bearings
When compared to bearing arrangements • single, universally matchable bearings
Larger bearings are available, standard, with with open bearings and external seals, those • matched bearing sets
steel balls and can be supplied with ceramic with sealed bearings provide a number of • sets of universally matchable bearings
balls on request. advantages including:
As ceramic balls are considerably lighter
and harder than steel balls, hybrid bearings • extended bearing service life
can provide a higher degree of rigidity and • reduced need for maintenance
run considerably faster than comparably • reduced inventory
sized all-steel bearings. The lower weight of • reduced risk of lubricant contamination
the ceramic balls reduces the centrifugal during mounting and operation
forces within the bearing and generates less
heat. Lower centrifugal forces are particu- Sealed bearings are identified by the desig-
larly important in machine tool applications nation prefix S (suffix /S).
where there are frequent rapid starts and
stops. Less heat generated by the bearing
means less energy consumption and longer
bearing and grease service life.
A hybrid variant is available, standard, for
bearings with a bore diameter up to 85 mm. Certain sizes are available in a sealed variant.
Steel balls Ceramic balls Open variant Sealed variant
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Applications
The SKF assortment of super- precision Other applications include dynamometers series, to provide the best possible combin-
angular contact ball bearings in the 72 .. D for engine testing and Parallel Kinematic ation of rigidity, load carrying capacity, heat
(E 200) series offers solutions to many bear- Machines (PKM). A dynamometer requires a generation and bearing service life.
ing arrangement challenges. Their ability, high degree of rigidity and high-speed cap-
among others, to provide a high degree of ability. To limit the errors in the readings, low
rigidity and accommodate heavy loads at vibration and noise levels as well as low fric-
relatively high speeds is beneficial for a tion are critical. A PKM requires high load carry -
variety of applications. ing capacity and a high degree of rigidity to
Lathe spindles, for example, require high limit bending, which lowers machine
load carrying capacity and high positioning accuracy.
accuracy. Depth of cut and feed rates are For these and other precision applica-
usually pushed to the limit, and depend on tions, there is an optimal arrangement
the required surface finish. incorporating bearings in the 72 .. D (E 200)
Applications Requirements Solution
• Machine tool spindles • High load carrying capacity
• Lathes (main spindle, tailstock) • High degree of rigidity
• Grinding machines • High-speed capability
• Boring machines • High positioning accuracy
• Parallel Kinematic Machines (PKM) • Long service life
• Dynamometers for engine testing • Low vibration and noise levels
• High-speed turbochargers • Low friction
• Facilitated mounting
• Increased machine uptime
SKF super-precision angular contact ball
bearings in the 72 .. D (E 200) series
8
A
9
Bearing arrangement design
Single, universally matchable
Bearing arrangements using SKF super- without the use of shims or similar devices.
bearings
precision angular contact ball bearings in The bore and outside diameters of these
the 72 .. D (E 200) series can be designed bearings are matched to within a maximum
using single bearings or bearing sets. An Universally matchable bearings are specif- of one-third of the applicable permitted
example of the ordering possibilities for a ically manufactured so that when mounted diameter tolerance, resulting in an even
three-bearing arrangement is provided in in random order, but immediately adjacent better load distribution when mounted,
table 1. to each other, a given preload and/or even compared to single, universally matchable
load distribution is obtained without the use bearings.
of shims or similar devices. These bearings
Single bearings
can be mounted in random order for any
Sets of universally matchable
desired bearing arrangement.
bearings
Bearings in the 72 .. D (E 200) series are Single, universally matchable bearings
available as single (stand-alone) bearings or are identified by the designation suffix G (U).
single, universally matchable bearings. The bearings in these sets can be mounted
When ordering single bearings, indicate the in random order for any desired bearing
Bearing sets
number of individual bearings required. arrangement. The bore and outside diam-
eters of universally matchable bearings in a
Bearings in the 72 .. D (E 200) series are set are matched to within a maximum of
Single bearings
available as matched bearing sets or as sets one-third of the applicable permitted diam-
Single bearings are intended for arrange- of universally matchable bearings. When eter tolerance, resulting in an even better
ments where only one bearing is used in ordering bearing sets, indicate the number load distribution when mounted, compared
each bearing position. Although the width of of bearing sets required (the number of to single, universally matchable bearings.
the bearing rings is made to very tight toler- individual bearings per set is specified in the Like single, universally matchable bear-
ances, these bearings are not suitable for designation). ings, sets of universally matchable bearings
mounting immediately adjacent to each are identified by the designation suffix G (U),
other. but their positions in the designation differ
Matched bearing sets
(† table 1).
Bearings can be supplied as complete bear-
ing sets consisting of two, three or four
bearings. The bearings are matched to each
other during production so that when
mounted immediately adjacent to each
other, in a specified order, a given preload
and/or even load distribution is obtained
Table 1
Example of the ordering possibilities for a three-bearing arrangement
Design criteria What to order Bearing designation1) Order example
Bearing arrangement is not known Three single, universally matchable 72 .. DG../P4A 3 x 7214 CDGA/P4A
bearings (E 2.. 7CE .. U..) (3 x E 270 7CE1 UL)
Bearing arrangement is not known and A set of three universally matchable 72 .. D/P4ATG.. 1 x 7214 CD/P4ATGA
improved load distribution is desirable bearings (E 2.. 7CE .. TU..) (1 x E 270 7CE1 TUL)
Bearing arrangement is known Three bearings in a matched set 72 .. D/P4AT.. 1 x 7214 CD/P4ATBTA
(E 2.. 7CE .. T..) (1 x E 270 7CE1 TDL)
1) For additional information about designations, refer to table 16 on pages 30 and 31.
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