skf energy efficient deep groove ball bearings brochure

8/10/2019 SKF Energy Efficient Deep Groove Ball Bearings Brochure

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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.


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


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]


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


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


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


can be estimated using

kr qdm w2Frm= (5,2 n)2/3 T

skf energy efficient deep groove ball bearings brochure

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