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Rolling Bearings Contribute to the EnvironmentRolling Bearings Contribute to the EnvironmentRolling Bearings Contribute to the EnvironmentRolling Bearings Contribute to the Environment
Japan Bearing Association
Global environment committee
1. Introduction
Environmental problems the world over, beginning with depletion of the ozone layer in the 1980s, have lead to global warming,
stripping of natural resources, toxic waste, and so on. The progress we enjoy now may spell out the ultimate demise of our
very existence as humans in general.
Global environmental issues are related to the activities of every individual. Although not readily apparent, rolling bearings,
being an essential element in various industries, also have an impact on the environment. Originally designed to use less
energy and save natural resources through their entire life, rolling bearings are environmentally friendly and have little
negative impact on the environment.
Specifically, one distinctive feature of bearings is low friction. This contributes to the use of less energy of all rolling areas.
Regarding bearing production, recycled steel from scrap is mostly used for the raw material of bearing steel, and machining
grids. Chips at the production process are also melted and recycled. With these points in mind, we want to discuss and touch
on the topic of the environmentally friendly aspects of rolling bearings.
2. Energy Conservation
Since the industrial revolution, energy consumption has grown significantly. Most energy requirements are filled by the
consumption of fossil fuels, such as petroleum products, and coal. These energy sources are limited, though, and will
eventually be depleted in the future. During the 1970s oil crisis, attention was focused on energy conservation measures,
with the realization that fossil fuels are finite. In the later half of the 1990s, a new theme, the reduction of carbon dioxide,
was proposed with the primary focus on global warming and what industries can do to achieve further savings in energy
utilization.
Rolling bearings, which we produce, play a significant role in energy conservation. This has been our contribution since
ancient times. Once we understood the basic concepts, we were moving hefty objects of wood or stone on rollers. We
learned that this required much less effort than just sliding. We finally understood that using rollers could reduce frictional
resistance, thus contributing to energy conservation. From day one, rolling bearings have been contributing to energy
conservation. Though indirect, the contribution our products make to industries in regards to their energy conservation is
enormous. Since this effect is difficult to measure in numbers, the average person might not be aware of the contributions
bearings make. The loss and waste of energy through frictional resistance of rolling bearings has to be reduced even further
to its barest minimum. Therefore, bearing manufacturers need to increase their efforts to further their contributions to
industries.
Here are some examples of how bearings contribute to energy conservation.
2.1 Energy Conservation by Rolling
The most basic characteristic of rolling bearings is low friction. Compared to sliding bearings, substantial savings in energy
can be attained by replacing sliding bearings with rolling bearings.
2.1.1 Contribution of Automotive Rolling Bearings
Figure 1 shows the torque loss of sliding bearings and rolling bearings. As shown in Figure 1, the torque loss of rolling
bearings is small for the entire range of speed. This clearly indicates that rolling bearings contribute to energy conservation.
For example, if all the automobiles in Japan only used sliding bearings and ran at the speed of 60 km/h, which is the point of
least torque loss difference, the increased amount of fuel consumption would be 480,000 kl (crude oil). The number of
barrels of oil, when stacked one of top of the other, would be 240 times higher than Mt. Everest.
Figure 1 Comparison of energy consumption for vehicles with and without rolling bearings.
2.1.2 Contribution of Rolling Contact for Roller Tappets and Rocker Arms
Originally, the roller in an engine would slide on the cam. Now, many engines use roller tappets that have a hardened steel
roller turning on needle bearings. This reduces friction and improves fuel economy (Figures 2 and 3). For most sedans,
engine rpm is mostly in the low and medium ranges. In these ranges, since the loss of the valve system is relatively high
among entire engine frictional loss, introduction of rolling bearings in valve system has contributed to better fuel economy
(Figure 4).
Figure 2 Design of rocker arms (See Document 1)
Test conditions
Actual engine motoring
Oil temperature: 100°C
Sliding rocker arm
Rolling rocker arm
Runnin
g to
rque (N·m
)
Camshaft speed (rpm)
Conventional rocker arm (Sliding type) Rocker arm with needle bearings
0.0
2.0
4.0
6.0
8.0
0 30 60 90
Car speed (km/h)
Sliding bearings
(Rolling bearings are not used)
Rolling bearings
Energy conservation
by rolling bearingsTorq
ue loss
(N·m
)
Figure 3 Running torque of actual engine head motoring
Figure 4 Improved fuel economy with rocker arms and needle bearings (See Document 1)
2.1.3 Contribution of Automotive Transmission Rolling Bearings
Needle roller bearings are used in transmission gear shafts (Figure 5). In the past, sliding bearings had been used for these
applications. Rolling bearings replaced the sliding bearings with no change to space requirements. Frictional torque has been
reduced by about one-tenth with increased machine and fuel efficiency resulting in greater energy conservation.
Figure 5 Application of rolling bearings in a sedan transmission
2.1.4 Contribution of Fan Motor Miniature Ball Bearings
Let’s compare the consumption of electricity for two 80-mm fan motors, each running at 2,550
miniature ball bearings (Bearing number: 693) and the other incorporates sliding bearings (Sintere
follows:
Miniature ball bearings: 0.9 w
Sliding bearings: 1.2 w
These results show that if 100 million fan motors ran for 8 hours a day, 250 days a year, the tota
be 6 million kw·h/year. If powered by plants using fossil fuels, the reduction in carbon dioxide em
2.2 Energy Conservation by Reducing Torque in Rolling Bearings
In our efforts to further conserve energy, we have made efforts to reduce bearing torque loss.
2.2.1 Contribution of Low-Friction Tapered Roller Bearings
0 1 2 3 4 5 6 7 8 9
Fuel efficiency (%)
100km/h
80km/h
60km/h
40km/h
10-mode fuel consumption
Idling fuel consumption
Fie
ld fuel
R: Radial type
S: Axial type
rpm. One fan incorporates
d metal). The results are as
l energy conservation would
issions would be 5,280 tons.
Tapered roller bearings used in automotive powertrains have rather high frictional resistance compared to other rolling
bearings. The bearing running torque has been reduced 20 to 50% by reducing friction coefficient between the large head of
the roller and the rib surface, and by applying crowning on the outer ring raceway (Figure 6).
Figure 6 Running torque of low-torque tapered roller bearings
2.2.2 Contribution of Power Hand Tool Bearings
Hand tools include tools powered by electric motors, such as grinders, drills, cutters, etc. Figure 7 shows the bearing
application for a grinder. Running conditions for these types of bearings are harsh and require superior wear and corrosion
resistance. Various conditions include operating under high speeds (some tools exceeding 20,000 rpm), and exposure to dust,
water and mist.
Sealed deep-groove ball bearings are most popular for hand tools. If dust or water resistance is required, contact-type seals
are often incorporated.
The very nature of hand tools requires that they are light in weight, have low vibration, and generate as little heat as possible.
These requirements extend directly to the bearings of such tools. In order for the tools to meet user requirements, the
bearings, too, must have low vibration, and generate as little heat as possible (low torque).
Power hand tools that meet the above requirements also require smaller motors resulting in less energy consumption. To
achieve all of these, the following innovations have seen a 50% increase in improvements:
(1) Adoption of low-torque contact seals
(2) Selection and quantity of greases suitable for high speeds
(3) Low torque design of bearing interiors
Figure 7 Bearing arrangements in a power grinder
Bearing bore: ø30, ø50 mm
Axial load: 3.92 kN
Lubricant viscosity: 23.3 mm²/s
Conventional bearings
Improved bearing I
Improved bearing II
Runnin
g to
rque
N·m
Speed (rpm)
2.2.3 Contribution of Seal and Seal Recess Improvements (Standard deep groove ball bearings) for Low Torque Bearings
Running torque has been reduced 20% by redesigning the seal and seal recess of sealed deep groove ball bearings (Figure 8).
Figure 8 Low torque achieved by improvements in the seal recess
The examples and information provided thus far clearly indicate the positive impact that bearings have had on saving natural
resources, and show how bearings can assist various industries in lowering energy consumption. As suppliers of such
bearings, we promise to maintain our endeavor to develop optimum bearings to meet various needs of both industry and the
environment.
3. Saving of Natural Resources
3.1 Light Weight
3.1.1 Streamlining Massive Bulk
In the past era of excess, emphasis was on performance while structural size was ignored. Current trends require that we
review the past era of waste and excess. To meet modern requirements of efficiency, reliable design and production
technologies are indispensable.
In comparison to the overall size of the machine or equipment, bearing weight or size is not so great. However, production of
compact and light bearings, while maintaining reliability, allows for more freedom in end-product design, substantially
contributes to making machines and equipment more lightweight.
Figure 9 shows the axle bearings of Japan’s shinkansen “bullet” train. Forty years ago, the 0-series model (Maximum
speed: 250 km) utilized an axle bearing that consisted of one double-row cylindrical roller bearing for radial load, and one
deep groove ball bearing for axial load. A single axle bearing weighed in at 75 kg. Then, 30 years later, the 300-series model
(Maximum speed: 300 km) was introduced. Bearing mass was drastically reduced to only 31 kg by utilizing improved
materials and by design reviews. The most obvious change was in eliminating the deep groove ball bearing for axial load and
applying all the axle load to double-row cylindrical roller bearings instead. Bearing mass of the latest mode, the 700-series,
is only 25 kg. Since each coach is installed with 8 sets of bearings, coach mass is directly reduced by 400 kg (75 – 25) × 8).
Furthermore, bearing size has also been reduced. The lighter and smaller bearings allow for even greater energy
conservation of the bullet train.
0-series (1964) 300-series (1992) 700-series (1999)
Mass 75 kg 31 kg 25 kg
φ12
5
φ13
0
φ12
0
φ12
0
130
155165
170
210
215
55
φ26
0
φ28
0
φ23
0
φ22
0
Conventional New 0
100
Ball bearing: 6908, both sides sealed
Inner ring rotation: n = 1800 rpm
Runnin
g to
rque ( %
)
Conventional New
Figure 9 Evolution of axle bearings for Japanese shinkansen “bullet” trains
Figure 10 provides an example of a hard disk drive (HDD) used for data storage devices in personal computers. During the
1970s, HDDs grew in popularity as data storage devices for large computers. Disk diameter was larger than 10 inches, and
the spindle was supported by precision angular contact ball bearings of around 40 mm bores. Recently, the density of
personal computer HDDs has drastically increased. Disk diameter was reduced to 3.5 inches, and then 2.5 inches and
1.8-inch disks are appeared. To meet the demand for reduced disk sizes, bearings installed into the disk support became
small, extra small ball, and finally miniature. Now, miniature ball bearings are industry standard. High precision bearings have
helped make high-density, compact, and high-speed HDDs a reality. The dynamic running accuracy (NRRO: non-repetitive
runout) of support bearings for HDDs has improved to the 0.01 µm-level (Figure 11)
Figure 10 Cross-sectional view of
Figure 11 Required NRRO
3.1.2 Integration or Built-in Surrounding Parts (Unificat
The amount of space used by a part, its mass, or the n
unifying the bearings and other surrounding component
conservation.
Figure 12 shows an example of automotive wheel hub un
ball bearings, were used. Specifically, automakers assem
configuration evolved to double-row angular contact ba
being integrated into the surrounding components. Hub
lighter weight contributes to improved fuel economy, an
for automakers. Moreover, variations in tightening torqu
accurate. Overall performance, quality, stability, and s
S
Bearing
NR
RO
, µm
Year
Miniature ball bearings
a HDD spindle motor
for HDD spindle motors and bearings
ion)
umber of related components, can be reduced by integrating or
s. Direct use of the mating shafts can result in resource and energy
it. 40 years ago, a pair of tapered roller bearings, or angular contact
bled the bearings with the housing and the hub shaft. The original
ll bearings. With the second and third generations, bearings were
mass is reduced by 20% owing to the reduction of components. The
d integration of hub components contributes to labor cost savings
e at the automaker’s bearing assembly line is simplified and more
afety of the vehicles are enhanced.
pindle motor
Second generation Third generation Integrated
+ constant velocity joint + constant velocity joint constant
velocity joint
Figure 12 Evolution of wheel hub unit bearings
Figure 13 shows an example of needle roller bearings. Needle roller bearings have less cross-section height compared to
cylindrical roller bearings and are more lightweight. The example shows installation of needle rollers with a cage and
drawn-cup needle roller bearings. By utilizing the housing or shaft of mating machines as a bearing ring, these bearings can
reduce bearing height.
Figure 13 Needle roller bearings in a planetary gear reducer
3.1.3 Thin Cross-section of Standard Bearings
Deep groove ball bearings, which are easy to use, are most common for the 60, 62 and 63 series. Ever since bearing
manufacturers started producing the 67 series, in addition to the 68 and 69 series of which cross-section is small, users can
easily procure thin cross-section bearings.
Thin cross-section bearings, as shown in Figure 14, have a smaller outside diameter and width if the bore diameter is the
same. Therefore, they are more lightweight and compact.
K: Needle rollers with cage and rollers
T: Drawn-cup needle roller bearing
64 series
63 series62 series60 series
69 series
68 series
67 series
Figure 14 Comparison of cross sections of bearing series
3.1.4 Adoption of Pressed Steel
Bearing rings can be made of pressed steel if the application is limited and the pressed part can fulfill the reliability required
for bearings. For these types of bearings, the rings are thinner and the bearing mass can be reduced.
Figure 15 shows an automotive clutch release bearing whose rings are replaced with pressed rings. Mass reduction is about
10%.
Conventional (interchangeable) Pressed steel
(Machined rings) (Pressed rings)
Figure 15 Clutch release bearings
3.2 Long Life
Bearing manufacturers have tried to improve and develop bearing materials through cooperative research with steel
manufacturers to extend bearing life and improve reliability. Research includes reduction of impurities and oxygen in steel,
special materials for special applications, development of special heat treatment, and surface modification.
The results are lightweight and long-life bearings that contribute to energy conservation. Further efforts for longer life are
continuously being promoted to support all industries in the future. The following are examples contributing to resource
conservation.
3.2.1 Longer Life by Improving Purity of Bearing Steel
To meet the requirements of lightweight and fuel efficient cars, maintenance-free steel mill equipment, and bullet train
related equipment, bearing running conditions have been severe. The demand for longer life is never-ending. By the early
90s, steel life was seven times of that from the late 60s. The purity of steel was improved by reducing oxygen content and
non-metallic incursions (oxide impurity which is origin of fatigue flaking) in bearing steel (SUJ steel: equivalent to AISI
52100) (Figures 16 and 17).
LD
intro-
duced
Oxy
gen in s
teel,
ppm
LD: Ladle vacuum degassing
RH: RH vacuum degassing
LF: Ladle refining
CC: Continuous casting
EBT: Eccentric bottom tapping
RH introduced
Years
LF introduced
EBT introduced
CC introduced
Figure 17 Evolution of rolling fatigue life of bearing steel (ball bearing: 6206)
3.2.2 Longer Life by Development of Special Bearing Steels
To restrict cracking extension, bearing manufacturers have developed bearings whose life is six times longer compared to
conventional bearings. Bearing steel structural phase and temper resistance are strengthened by adding Ni and Si in
cooperation with steel manufacturers (Figure 18).
Figure 18 Fatigue life test results of high-strength bearing steel
3.2.3 Longer Life at High Temperature with Special Bearing Steel Development
One of the requirements of the steel mill process is longer life at high temperatures. This is in addition to the already severe
conditions of rolling bearings. By developing special bearing steel with an added alloy component, longer life can be
achieved for up to 250°C. Life is 3.5 times at room temperature and 30 times at 200°C compared to conventional bearing
Bear
ing
life, h
Vacuum degassing
Ladle refining
Continuous casting
> 7 times
�Rated life
Years
Accum
ula
ted
failu
re p
roba
bilit
y, %
● Clean oil lubrication
Test bearings: 6206 ball bearings
Load: 9 kN
Lubricating oil: #68 turbine oil
Calculated life General
bearing
steel
High-
strength
bearing
steel
Life, h
steel (Figure 19).
Figure 19 Life test at 200°C
3.2.4 Longer Life Under Contaminated Lubricating Oil for Special Heat-Treated Bearing Steel
To satisfy longer life requirements of transmission bearings, which are used under severe running conditions, that is, running
under contaminated oil with steel chips, we developed bearings with a life that is 10-times longer compared to conventional
bearings. This was accomplished by applying special heat treatment to obtain the optimum retained austenite and to form an
improved hard surface (Figure 20).
Figure 20 Fatigue life test of tapered roller bearings with optimum steel and
heat treatment under contaminated oil
Life (× 105) Life ratio
SUJ2 9.1 1
STJ2 No flaking > 30
Accum
ula
ted
failu
re p
roba
bilit
y, %
Test temperature: 200°C
Test-piece: ø47 × 7 mm plate
Used balls: ø6.35 (1/4”) Si3Ni4 balls
Contact stress: 5.5 GPa
Loading speed (frequency): 3000 times/min
Lubricant: Ether-base oil
103 107105 108
99
5
10
20
80
50
1
Life (load cycle)
SUJ2
STJ2 A
ccum
ula
ted f
ailu
re p
robab
ility
, %
Life (h)
● Contaminated oil lubrication
Specimen: TRA0607RYR
Load: Fa = 13.7 kN
Fr = 20.7 kN
Speed: 2000 rpm
Foreign particles: Total 0.12 wt% (1.1 g/l)
General
bearings
Improved
bearings
3.2.5 Longer Life by Insulated Layer (Film)
Electric corrosion (scales and chips) occurs in bearings for railway traction motors due to the passing of an electric current
through the bearings. Scales and chips decrease bearing life. To prevent passing of the current, an insulated layer
(sputtering of ceramic or PPS injection molding) is provided on the exterior of the outer ring. By applying high insulation
(more than 1000 MΩ), bearing life is extended two to three times longer than conventional bearings (Photos 1 and 2).
Photo 1 Ceramic-insulated bearings
Photo 2 PPS-insulated bearings
3.3 High Speeds
Rolling bearings used to support rolling parts of all industries are constantly being developed to meet the requirements of
high speeds and performance year after year.
Figure 21 shows the history of high speeds for rolling bearings of machine tool main spindles. Figure 22 shows the present
conditions of high-speed bearings by industry.
.
Figure 21 History of rolling bearing speeds for machine tool main spindles
d·n value: Bearing bore diameter, d (mm) × speed, n (rpm)
d·n
val
ue×
10
6
85 90 95 2000 1965 70 75 80
0.5
1.0
1.5
2.0
2.5
0
Lathes and milling
machines
Tapered roller bearings
(Forced lubricating
oil circulation)
Machining centers, NC lathes
and milling machines
High-speed machining centers
High-speed angular
contact ball bearings
Ceramic ball bearings
(Oil-air lubrication) High-speed machining centers
Ball bearings with ceramic balls
(Grease lubrication)
Ultra high-speed or high rigidity machining centers
Angular contact ball bearings
Cylindrical roller bearings
(Jet lubrication)
Years
Angular contact ball bearings
Cylindrical roller bearings
(Grease lubrication)
To achieve
(lubrication,
ceramic bal
Besides the
also improv
conservatio
The tenden
high-speed
4. Recycling
Refuse of b
which are a
(Photos 3 a
Aircra
ft
Mac
hin
e t
ools
C
ars
Ele
ctr
ic
appl
iances
Speed
d·n value (× 106)
T
C
Application
Figure 22 The present co
such high speed running of rolling
cooling, etc.) play important roles
ls, and low dynamic loss minute lu
contribution to industrial product
ed to meet requirements of high s
n.
cy of high speed requirements will
technology.
of Bearing Components
earing materials at the press proc
bout 100 thousand tons per year in
nd 4).
Oil-
Jet engines
Internal
grinders
urbochargers
leaner motors
Jet
nditions
bearings
. Beari
brication
ion activ
peed. Th
increase
ess is rep
Japan,
air
Mist
of hi
, opt
ng pr
(oil-
ities
is ha
stea
roc
are r
1 3
GreaseLubrication method
gh-speed bearings by industry
imum design of rolling bearings a
eload switching technology, low-
air lubrication) are the key point
, bearings used in transportation
s helped reduce costs and has c
dily and we are enthusiastically p
essed as steel scrap. Machining c
emoved from water and oil and re
Present Near future
Machining
centers
Magnetic
clutches
2
nd rela
heat ge
s for at
and info
ontribu
romotin
hips an
cycled
4
Bearing bore
ted technologies
neration interior design,
taining high speeds.
rmation equipment have
ted to energy
g the development such
d burrs from processing,
as raw material for steel
Photo 3 Billets of grinding chips
Photo 4 Billeting machine of grinding chips
In addition to the above, recycling systems for plastic materials have been established. We continue to make efforts to
reduce or reuse the exhaust or used oils at the production process.
Rolling bearings are made of steel. The bearings in cars and home electric appliances, which are major application items,
are reclaimed and recycled as an iron resource.
The Japan Bearing Association increased recycling by 75%, 10 years ahead of schedule. We are now working on targeting
new activities and establishing new goals.
5. Improvement of Noise Characteristics
5.1 Air conditioners
Applications which require low noise are home electric appliances, information equipment, audio-visual equipment, etc.
Fan motors in air conditioners or air cleaners, which are used during night or while people are sleeping, must be quiet in
operation. Figure 23 shows the change of noise level of air conditioners and Figure 24 shows the change of sound level of
bearings for air conditioner fan motors. Clearly, advancements made in ball bearing noise has lead to quieter air conditioners.
40
50
60
Exterior equipment
B
Figure 23 Evolution of air conditioner noise levels
0
20
40
60
80
100
1980 1985 1990 1995 2000
Years
Vib
ration*1
%
*1 Vibration: Anderon value
Ball bearings (100 at 1980)
Figure 24 Evolution of fan motor bearing sound levels
5.2 Traction Drives
Figure 25 shows a traction drive reducer system which utilizes rolling traction force with ring and rollers in a conventional
planetary gear device.
Figure 25 Traction drive reducer system
Sun roller Planetary rollers
Ring
A
A
Low
spe
ed
side
Hig
h s
peed
side
A-A
By replacing gears with rolling contact, noise and vibration are reduced compared to a conventional power transfer system
as shown in Figure 26.
0
5
10
15
20
0 1000 2000 3000 4000 5000
Sun roller speed, rpm
Vib
ration m
/s2
Traction drive
Planetary gears
Figure 26 Comparison of vibration
5.3 CT Scanners
A CT scanner (Photo 5), which is one of many valuable medical devices, consists of a patient bench and inspection unit. As
shown in Figure 27, the cathode-ray tube and detector (imagery system), are attached to a rotating frame of the inspection
unit. A bearing of 1 m in diameter supports the rotating frame. Though the mechanism is encapsulated, the bearing must still
operate quietly. Bearing speed is increasing to shorten the inspection time and to improve image accuracy. This helps to
reduce stress and burden of the patient.
Photo 5 CT scanner
Cathode-ray tube
Rotating frame
Bearing
Patient bench
Fixed frame
Drive beltDetector
Figure 27 Structure of CT scanner
In medium and low speed models (rotating speed: 40 ~ 90 rpm), a 4-point contact ball bearing (Figure 28) is usually used. To
obtain low noise operation, a resin cage is used in the bearing and internal clearance is settled so that the balls at the
unloaded zone generate little or no noise.
In medium- and high-speed models (rotating speed: 80 ~ 120 rpm), a back-to-back arrangement of angular contact ball
bearings with resin cages (Figure 29), or preloaded double-row angular contact ball bearings (Figure 30), are used to restrict
noise by increasing bearing rigidity. Moreover, the double-row angular contact ball bearings, which are integrated with
surrounding part, enable low noise running with high accuracy.
Figure 28 4-point contact ball bearing
Figure 29 Back-to-back angular contact ball bearings
Figure 30 Integrated double-row angular contact ball bearings
6. Reduction of Materials Inflicting an Environmental Burden
Chemical materials, which are dissolved from product waste and garbage, such as mercury, lead, cadmium, arsenic,
sexivalent chrome, etc, cause an environmental burden.
Rolling bearings, whose major component materials is steel, contain little such materials. Used bearings are usually
recycled together with installed machines, thus, bearings have little effect on environment.
However, some bearing lubricants place a burden on the environment. Usage is very little, as is the case with lead-based,
extreme pressure additives that are contained in lubricating greases. Regardless, we are now replacing such greases with
non-lead type greases to reduce any additional burden on the environment.
In addition, we will continue to develop and make modification to our grease. We have developed and marketed
environmentally conscientious greases that have excellent decomposition characteristics. This is accomplished utilizing the
bacteria that occur naturally in the water and soil of fields, rivers, lakes, and oceans. We have developed greases with safety
in mind and. Results of living organism impact tests of our greases confirm that we achieved a mark of less than one-tenth
of the new eco-mark criteria set for fish (Figures 31 and 32).
Figure 31 Natural decomposition of greases
Figure 32 Impact on ecology
Special fron and 1.1.1-trichroloethane have been used at bearing production lines for cleaning purposes. They are being
replaced or eliminated by new environmentally friendly cleaning methods or equipment, such as a pure water cleaning device
(Photo 6), and a cleaning device using hydrocarbon-base agent, etc.
Natural decomposition
Natural decomposition capability is very high and environmental-friendly (natural decomposition rate: 97.3%)
Nat
ura
l de
com
posi
tion r
ate %
Natural decomposition grease Lithium-mineral oil grease (general grease)
Low impact on ecology system
Acute poisonous test using killifish
LC50 value after 96 hours: more than 1000 mg/l
(New criteria for eco-mark: 100 mg/l)
LC50: 50%-fatal dose density of test on live organism
Judging criteria of poison against ecology
Relative poisonous level LC50 value (mg/l)
Relatively nonpoisonous > 1000
Actually nonpoisonous 100 ~ 1000
Slightly poisonous 10 ~ 100
Poisonous 1 ~ 10
Very poisonous < 1.0
Photo 6 Pure water cleaning system
Although rolling bearings contain few materials that create an environmental burden, we steadily make efforts to reduce
further environmental impact in areas that are not so readily visible.
7. Futures
Taking this all into consideration, we believe you can understand the great contribution to the Earth's environment of rolling
bearings that are used in all rotating equipment and devices.
In the 21st century, laws to prevent further global warming will be rapidly expanded to not only affect home appliances, but
also all other industries including those related to transportation and IT. Therefore, the ultrahigh rigidity or ultra long life of
rolling bearings should be achieved under the development of zero-impurity next-generation bearing materials. Ultra-low
torque bearings with optimum geometric design and extremely low viscosity greases should be also studied.
Together with the promotion of a recycling-oriented society, separable rolling bearings with easily classified reclaiming of
components will become major bearings and the synthetic rubber for seals will be replaced with paper. Grease base oils will
be replaced with animal fat or vegetable oil and environmental contaminated materials will be eliminated from all products. It
is not a dream that all the components will be reused or recycled.
At the rolling bearing production process, wet cutting or grinding using oil or water-based coolants will be changed to dry
cutting or grinding, free of oil mist. This will create a comfortable working environment and zero garbage at the production
process, thus achievement of zero emissions is feasible.
With bearing industry action plans, together with member companies considering the above conditions, the Japan Bearing
Association, Global environment committee is aggressively promoting energy conservation and garbage reduction. We will
study to make environmentally friendly products a long-term goal utilizing the lifecycle assessment (LCA) analysis.
<Reference>
Document 1: N. Miyamura, S. Nagano, K. Asano, I. Tanaka,
“Development of needle roller type rocker arms”(Japanese language), Internal Combustion Engines, 26 (1987)