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SKF Energy Efficientdeep groove ball
bearingsReduced friction for reduced energy use
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SKF the knowledge engineering company . . . . . . . . . . . . . . 4
SKF Energy Efficient bearings. . . . . . . . . . . . . . . . . . . . . . . . . 6
Engineered to promote sustainability . . . . . . . . . . . . . . . . . . . . . 6
Reduced friction reduced energy use . . . . . . . . . . . . . . . . . . 6
Longer service life lowers cost of ownership . . . . . . . . . . . . . . 6
SKF E2 deep groove ball bearings. . . . . . . . . . . . . . . . . . . . . . 7
For light- to medium-load applications . . . . . . . . . . . . . . . . . . . 7
Reduced frictional moment . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Extended grease life means longer bearing service life . . . . . . 7
Test results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Frictional moment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Cage behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Application recommendations. . . . . . . . . . . . . . . . . . . . . . . . . 10
Determining fatigue life using life equations . . . . . . . . . . . . . . 10
Determining permissible speed . . . . . . . . . . . . . . . . . . . . . . . 10
Calculating frictional moment . . . . . . . . . . . . . . . . . . . . . . . . . 10
Determining the service li fe of the grease . . . . . . . . . . . . . . . . 11
Product data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Grease fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Cages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bearing data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Internal clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Misalignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Minimum load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Axial load carrying capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Equivalent bearing loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Designations and package identification . . . . . . . . . . . . . . . . . 13
Contents
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From one simple but
inspired solution to
a misalignment
problem in a textile
mill in Sweden, and
fifteen employees in
1907, SKF has
grown to become a
global industrial
knowledge leader.
Over the years, we have built on our exper-tise in bearings, extending it to seals, mecha-
tronics, services and lubrication systems.
Our knowledge network includes 46 000
employees, 15 000 distributor partners,
offices in more than 130 countries, and a
growing number of SKF Solution Factory
sites around the world.
Research and development
We have hands-on experience in over forty
industries based on our employees know-
ledge of real life conditions. In addition, our
world-leading experts and university part-ners pioneer advanced theoretical research
and development in areas including tribol-
ogy, condition monitoring, asset manage-
ment and bearing life theory. Our ongoing
commitment to research and development
helps us keep our customers at the forefront
of their industries.
Meeting the toughest challenges
Our network of knowledge and experience,
along with our understanding of how our
core technologies can be combined, helps
us create innovative solutions that meet the
toughest of challenges. We work closely with
our customers throughout the asset life
cycle, helping them to profitably and
responsibly grow their businesses.
SKF Solution Factory makes SKF knowledge and manufacturing expertiseavailable locally to provide unique solutions and services to our customers.
Working with SKF IT and logistics systems and application experts, SKFAuthorized Distributors deliver a valuable mix of product and applicationknowledge to customers worldwide.
Working for a sustainable future
Since 2005, SKF has worked to reduce the
negative environmental impact from our
operations and those of our suppliers. Our
continuing technology development resulted
in the introduction of the SKF BeyondZero
portfolio of products and services which im-
prove efficiency and reduce energy losses,
as well as enable new technologies har-
nessing wind, solar and ocean power. This
combined approach helps reduce the envir-
onmental impact both in our operations and
our customers operations.
SKF the knowledge engineeringcompany
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Bearings
SKF is the world leader in the design, developmentand manufacture of high performance rollingbearings, plain bearings, bearing units andhousings.
Machinery maintenanceCondition monitoring technologies and main-tenance services from SKF can help minimizeunplanned downtime, improve operationalefficiency and reduce maintenance costs.
Sealing solutionsSKF offers standard seals and custom engineeredsealing solutions to increase uptime, improvemachine reliability, reduce friction and powerlosses, and extend lubricant life.
MechatronicsSKF fly-by-wire systems for aircraft and drive-by-wire systems for off-road, agricultural and forkliftapplications replace heavy, grease or oil consumingmechanical and hydraulic systems.
Lubrication solutionsFrom specialized lubricants to state-of-the-artlubrication systems and lubrication managementservices, lubrication solutions from SKF can help toreduce lubrication related downtime and lubricantconsumption.
Actuation and motion controlWith a wide assortment of products from actu-ators and ball screws to profile rail guides SKFcan work with you to solve your most pressinglinear system challenges.
Our knowledge your successSKF Life Cycle Management is how we combine our technology
platforms and advanced services, and apply them at each stage
of the asset life cycle, to help our customers to be more
successful, sustainable and profitable.
Working closely with you
Our objective is to help our customers
improve productivity, minimize mainten-
ance, achieve higher energy and resource
efficiency, and optimize designs for long
service life and reliability.
Innovative solutions
Whether the application is linear or rotary
or a combination, SKF engineers can work
with you at each stage of the asset life cycle
to improve machine performance by looking
at the entire application. This approach
doesnt just focus on individual componentslike bearings or seals. It looks at the whole
application to see how each component in-
teracts with each other.
Design optimization and verification
SKF can work with you to optimize current
or new designs with proprietary 3-D mod-
elling software that can also be used as a
virtual test rig to confirm the integrity of the
design.
SKF Life CycleManagement
DesignanddevelopManufacture
and
test
Specif
icat
ion
Installan
dcomm
issi
on
Operateandmonitor
Main
tainandrepair
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SKF Energy Efficient bearings
Engineered to promotesustainabilityAs the need to conserve energy becomes
more important every day, the technology
that enables even a small reduction in
energy consumption is big news.
Drawing on over 100 years of engineer-
ing knowledge and unmatched expertise
in the field of tribology and related sciences,
SKF has developed a new, low-frictioncapped deep groove ball bearing. The SKF
Energy Efficient (E2) deep groove ball bear-
ing was the first bearing type, in the SKF
family of bearings, to represent the new SKF
E2 performance class.
While SKF bearings have continually
evolved toward ever greater efficiency and
reliability, this new performance class repre-
sents a significant breakthrough. SKF E2
deep groove ball bearings reduce frictional
losses in a bearing by 30% or more when
compared to an equivalent SKF Explorer
bearing. This means that when compared to
other manufacturers bearings, the reduc-
tion can be even more significant.
Designed for grease lubricated, light- tomedium-load applications, SKF E2 deep
groove ball bearings generate less frictional
heat which extends grease life and as a
consequence, bearing service life when
compared to an equivalent SKF Explorer
bearing.
With all their special features, this new
performance class of bearings is designed to
improve machine efficiency and advance
everyones goal of a sustainable planet.
Reduced friction reducedenergy use
Frictional losses waste energy energy that
could have been used to run machinery. Butmore importantly, it represents energy that
will not be available to future generations.
Therefore, reducing the amount of frictional
losses in the bearing by at least 30% is an
achievement with far-reaching implications.
The potential for energy savings on a global
scale is huge.
Longer service life lowerscost of ownership
Optimized to reduce frictional losses in thebearing and provide longer service life,
capped SKF Energy Efficient deep groove
ball bearings can last at least twice as long
as comparable SKF Explorer bearings in
light- to medium-load applications. This
means that in applications where conven-
tional bearings fail and are replaced, the
longer service life of SKF E2 bearings could
potentially halve the number of bearings
consumed over the machine lifetime or even
eliminate the need for replacement altogether.
In instances where an application is run-to-failure, SKF E2 bearings could conceivably
double the life of the application.
Optimized internal geometryreduces friction
The distinctive mark for SKF Energy Efficient products
Low-friction seals orshields on both sidesprotect effectively
from contaminationand retain thegrease fill
Specially formulatedgrease provides goodlubrication with mini-mum friction
New cage designreduces friction
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SKF E2 deep groove ball bearings
For light- to medium-load applicationsThe operating conditions for deep groove
ball bearings typically are characterized by
light- to medium-loads at relatively high
speeds. Typical applications include:
electric motors
pumps
fans conveyors
textile machines
SKF Energy Efficient deep groove ball bear-
ings are designed specifically for these types
of applications.
Reduced frictional momentDiagram 1illustrates the effectiveness of
SKF Energy Efficient deep groove ball bearings
in a 3 kW electric motor. In this example, the
motor was equipped with SKF Explorer deep
groove ball bearings with shields on both
sides and later with equivalent SKF E2 bear-
ings. The free running time after the power
was switched off was measured. With SKF
E2 bearings, the free running time was
about 50% longer.
Extended grease life meanslonger bearing service life
For capped deep groove ball bearings in
typical light- to medium-load applications,
fatigue failure is rarely an issue. Bearing
service life is almost always limited by
grease life.
2 000
1 500
1 000
500
00 5 10 15 20 25 30 35 40 45
Diagram 1
Speed-time curves after switching off an electrical motor
Time [s]
Speed [r/min]
50 60 70 80 90 100 110 120 130 140 150
100 000
10 000
1 000
+23 000(2,5) +15 500
(3,2)+7 250(3,2)
Diagram 2
Grease life comparison between SKF Energy Efficient grease andSKF Explorer grease for deep groove ball bearings at same runningtemperature
Operating temperature [C]
Grease life L10[h]
Operating conditions: Speed factor A = 300 000 mm/min Load: P = 0,066 C
nSKF E2 deep groove ball bearings with shields on both sides
nSKF Explorer deep groove ball bearings with shields on both sides
nSKF E2 deep groove ball bearings with shields on both sides
nSKF Explorer deep groove ball bearings with shields on both sides
Recommended operating conditions for
enhanced performance characteristics:
Load P 0,125 C
Speed n > 1 000 r/min
Compared to SKF Explorer deep grooveball bearings, SKF Energy Efficient deep
groove ball bearings can, in the same appli-
cation, last more than double the mean time
between failure due to both the specially
formulated SKF low-friction grease
( diagram 2) and their lower operating
temperature.
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Test results
Frictional moment
The frictional moment of an SKF Energy
Efficient bearing with shields on both sides
was measured under various operating con-
ditions. When compared with the frictional
moment of a standard SKF shielded deep
groove ball bearing, the E2 bearing showed,
on average, approximately a 50% reduction
( diagram 3). Compared to other manu-
facturers bearings, the percentage reductionin the frictional moment could be even
greater.
100
90
80
70
60
50
40
30
20
10
0
1
000
3
000
5
000
1
000
3
000
5
000
1
000
3
000
5
000
1
000
3
000
5
000
1
000
3
000
5
000
1
000
3
000
5
000
70 85 100 70 85 100
P = 0,1 C P = 0,066 C
Diagram 3
Frictional moment of a shielded SKF Energy Efficient deep groove ball bearing compared to an equivalent SKF Explorer bearing
Operating conditions:
Load
Temperature [C]
Cage test rig: comparison between standardpolyamide cage and E2 cage at 8 000 r/min.The E2 cage on the right shows signficantly lessdeformation.
Fig. 1Cage behaviour
The cage design is one of the key features
of SKF Energy Efficient deep groove ball
bearings. The fundamental redesign pro-
duced a lighter cage that is less susceptible
to deformation during operation. Fig. 1
shows the reduced deformation experienced
by a polyamide cage of an E2 bearing when
compared to the polyamide cage of an SKF
Explorer bearing.
Relative frictionalmoment [%] Frictional moment
of 6306-2Z/C3
Max. frictional moment ofSKF Energy Efficient bearings
Average frictional momentof E2.6306-2Z/C3
Speed [r/min]
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125
120
115
110
105
100
95
90
85
80
3 000 3 500 4 000 4 500 5 000 5 500 6 000
15 C
5 C
Speed [r/min]
Diagram 4
Operating temperature at different speeds, test results
OperatingtemperatureThe operating temperatures of shielded SKF
Energy Efficient deep groove ball bearings
and equivalent SKF Explorer bearings were
measured at certain speeds and compared
( diagram 4). Test conditions were:
Bearing: 6205-2Z/C3
Running time: 24 h at each speed interval
Ambient temperature: room temperature
Load: 0,5 kN radial
The test showed that the SKF E2 bearing
ran 5 to 15 C cooler than the standard
SKF Explorer bearing, depending on speed.
Similar results were observed for sealed
SKF E2 bearings.
Operating temperature [C]
nshielded SKF Energy Efficient deep groove ball bearings
nshielded SKF Explorer deep groove ball bearings
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Application recommendations
Determining fatigue life usinglife equations
The method used to determine fatigue life
is the same for both SKF E2 deep groove
ball bearings and SKF Explorer deep groove
ball bearings.
SKF recommends using the SKF rating
life equations as described in the SKF rolling
bearings catalogue or available online at
skf.com/bearings.
Determining permissiblespeed
Operating under the recommended load
conditions (P 0,125 C), the permissible
speed of SKF Energy Efficient deep groove
ball bearings is equal to the limiting speed
as listed in the product table. If an SKF E2
deep groove ball bearing is to be operated
outside the recommended operating condi-
tions or above the limiting speed, contactthe SKF application engineering service.
Calculating frictional momentCalculating the frictional moment for SKF
Energy Efficient deep groove ball bearings
can only be done with the calculation tools
provided online at skf.com/bearings. The
formulae and factors provided in the SKF
Rolling bearings catalogueare not applicable
to SKF Energy Efficient bearings.
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100 000
10 000
1 000
10050 70 80 90 100 110 120 130 140 150
A = 40 000
A = 100 000
200 000
300 000
400 000
500 000
600 000
650 000
Diagram 5
Grease life for SKF Energy Efficient deep groove ball bearings for load P = 0,05 C
Estimated grease life L10[h]
Operating temperature [C]
Table 1
Reduction factors for grease life,depending on load
Load P Reduction factor
0,05 C 10,1 C 0,70,125 C 0,5
0,25 C 0,2
Determining the servicelife of the grease
Under the recommended operating condi-
tions, the service life of the grease in capped
SKF Energy Efficient deep groove ball bear-
ings normally defines the service life of the
bearing and can be estimated using
diagram 5. The estimate is based on an L10grease life. This is defined as the period of
time, at the end of which, 90% of a suffi-
ciently large group of seemingly identical
bearings are still reliably lubricated.
Grease life depends mainly on the follow-
ing factors:
operating temperature
speed
load
The diagram provides grease life estimates
based on operating temperature and speed.
It is valid for light loads (P 0,05 C) and
bearings on a horizontal shaft. For more
heavily loaded bearings, the grease life must
be reduced. Appropriate reduction factors
are listed in table 1. For bearings on a verti-
cal shaft, the grease life should be halved.
The speed is considered using speed factorA:
A = n dm
where
A = speed factor [mm/min]
n = rotational speed [r/min]
dm= bearing mean diameter [mm]
= 0,5 (d + D)
To make adjustments for other operating
conditions, refer to the recommendations inthe SKF Rolling bearings catalogueor contact
the SKF application engineering service.
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Product data
SKF Energy Efficient deep groove ball bear-
ings are available in the 60 62 and 63
dimension series. The current assortment is
listed in the product table ( page 14). The
assortment will be expanded according to
customer demands. For the most up-to-
date information, contact your local SKF
representative or visit www.skf.com/bearings.
DesignsCapped bearings
Depending on series and size, SKF Energy
Efficient deep groove ball bearings can be
supplied with :
Z shields on both sides ( fig. 1)
E2 RSH contact seals on both sides
( fig. 2)
The sealed E2 bearings are supplied with a
new low-friction contact seal. The new seal
is made from acrylonitrile-butadiene rubber(NBR) and reinforced with a sheet steel
insert. The seal lip, which has a thin and
flexible design, minimizes the frictional
moment, while effectively protecting the
bearing from contaminants. The seal lip and
bearing groove contact have been optimized
to reduce friction.
NBR operating temperature range: 40 to
+110 C (40 to +210 F).
Table 2
Grease in SKF Energy Efficient deep groove ball bearings
Thickener Lithium soap
Base oil type Synthetic oil
NLGI consistency class 2
Temperature range[C] 50 55 150 190
[F] 60 130 300 375
Table 3
Requirement Shields Contact seals
Z RSH E2 RSH
Low friction +++ o +
High speed +++ o +
Grease retention o +++ +++
Dust exclusion o +++ +++
Water exclusionstatic +++ +++dynamic + +high pressure +++ +++
Symbols: +++ = best ++ = very good + = good o = fair = not recommended
a E2 RSH seal design for D < 25 mmb E2 RSH seal design for 25 mm < D < 52 mm
Fig. 1 Fig. 2
a b
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Grease fillThe bearings are filled with a special low-
noise, low-friction SKF grease ( table 2).
The bearings are lubricated for life and are
maintenance-free1).
Cages
SKF Energy Efficient deep groove ball bear-ings are fitted with a ball centred snap-type
cage made of a temperature-resistant glass
fibre reinforced composite polymer.
Bearing data
Dimension standards
The boundary dimensions of SKF Energy
Efficient deep groove ball bearings are in
accordance with ISO 15:1998. This makesthe bearings dimensionally interchangeable
with deep groove ball bearings of the same
size in the same dimension series.
TolerancesSKF Energy Efficient deep groove ball bear-
ings are manufactured to P6 tolerances for
dimensional accuracy. The width tolerance is
however reduced to:
0/60 m for bearings with an outside
diameter `110 mm 0/100 m for bearings with an outside
diameter > 110 mm
The running accuracy depends on the
bearing size and corresponds to:
P5 tolerances for bearings with an
outside diameter `52 mm
P6 tolerances for bearings with an
outside diameter > 52 mm `110 mm
Normal tolerances for bearings with an
outside diameter > 110 mm
Internal clearanceSKF Energy Efficient deep groove ball bear-
ings are manufactured with C3 radial inter-
nal clearance as standard. Bearings with
radial internal clearance other than C3 can
be supplied on request.
MisalignmentSKF Energy Efficient deep groove ball bear-
ings have the same operating characteristics
as SKF Explorer deep groove ball bearings.
In other words, depending on the various
influencing factors, the permissible angular
misalignment lies between 2 and 10 minutes
of arc. Misalignment can increase bearing
noise and reduce bearing service life. For
additional information, refer to the SKF
Rolling bearings catalogueavailable online at
www.skf.com.
Minimum loadRolling bearings should always be subjected
to a given minimum load. The requisite
minimum radial load to be applied to SKF
Energy Efficient deep groove ball bearings
can be estimated using
kr qdm w2Frm= (5,2 n)2/3 T