Trends and Future Prospects for Rolling Bearing Technologies

Transcription

1 Trends and Future Prospects for Rolling Bearing Technologies Yoshikiyo YUKAWA * Rolling bearings are mainly composed of inner/outer races, rolling elements and retainers and this has not basically changed from the Leonard Da Vinci era, but the scope of the basic and application technology is indeed extremely wide and deep. Recently various and severe needs for rolling bearings have increased and diversified due to improvement in various industries and movement of environment protection. Here technical trends and future views on rolling bearings and related unit products are briefly presented. Key Words: rolling bearing, technical trend, history, design, application, development 1. Introduction Rolling bearings consist of four parts: inner ring, outer ring, rolling elements and cage with little change in construction. From the perspective of rolling bearing engineering and pursuit of the best bearing for each application, however, this involves various technologies of unlimited depth. Koyo is convinced that pursuit of these technologies will enhance customer satisfaction, and will help to provide and maintain a better global environment. This involves development of new products and new technologies on a daily basis. In view of the 80th anniversary of Koyo's founding, this paper provides observations on bearings in the 21st century, taking changes in the social environment surrounding bearings into account. 2. Change in Social Environment and Adapting to Such Change The bursting of the "bubble economy" in Japan brought about the end of the rising economy. Growth of the global economy ushered in the age of intense competition. A shadow has even been cast on Japanese economic power that had been supported by manufacturing. Now that we have entered the 21st century, which is said to be the age of intelligence and ideas, let's consider what is demanded of bearings Change in Social Environment Surrounding Bearings 1) Environmental problems The Earth was 4.6 billion years old. During years before the interglacial period started, the temperature of the Earth had risen about 1 C. Scientists estimate that the global *Former director of Bearing Engineering Center, Bearing Business Operations Headquarters Senior executive director of Koyo Thermo Systems Co., Ltd. KOYO Engineering Journal English Edition No.159E (2001) temperature will rise 3.5 C in the worst scenario, or 1 C in the best scenario by the year This means that scientists expect the global temperature to rise as much in the next hundred years as it did over the past years 1). This is due to the radical increase in CO 2 gas discharged into the atmosphere. In other words, fossil fuels have been overused, and solving the energy and environmental problems will the theme of utmost importance for the 21st century. The bearing manufacturing industry feels it can contribute significantly from the aspect of reducing the amount of CO 2 discharged into the atmosphere by alternative sources of energy such as wind power generation. In a wide range of industries including the automobile industry, mechanical equipment always uses bearings for parts involving rotation. Continuous growth of bearings, which is as indispensable for industry as rice is for Oriental peoples, is based upon energy efficiency (reduced torque), reduced weight/size, and longer life. It would not be an overstatement to say sustainable growth depends upon reduction of CO 2 output. 2) IT revolution While the country is still not on road to economic recovery, businesses are devoted to restructuring in accordance with the IT revolution. In the information equipment field related to IT, manufacturers are suddenly switching to semiconductor electronic components that show a high potential for more compact size and lower cost. Cellular telephones and car radios will switch to semiconductor parts in the near future. Technical change and progress in this industry is extremely fast, the product cycle is short, and the keyword is nothing but speed. Amidst such an IT revolution, high speed rotation, high precision, low noise and low torque are demanded of bearings. New bearings will also probably have to be developed in order to contribute to the special environment needed for equipment for producing the semiconductors that support the IT revolution. 23

2 3) Smaller workforce due to aging population and fewer children There appears to be a cloud over population growth in China, and the population of Japan has also begun to sharply decline. It is estimated that the population will be reduced by one-half around the beginning of the 22nd century 2). This means the working population will be diminished without limit. What the manufacturing industry must consider here is how they can make things efficiently without relying on human resources Required Technologies for Bearings Figure 1 gives the social environment, requirements for bearings, and corresponding technologies for meeting those demands. Social environment Environmental problems IT revolution Reduction in working population Requirements for bearings Energy-saving (Low torque) Compact/lightweight Long life High speed High running accuracy Low noise Expansion of applications High speed Efficient production Fig. 1 Trends and bearing key technologies Corresponding technologies New bearing materials Bearing surface treatment Bearing lubricants Non-contact bearings Switch to units/modules Development efficiency reform by IT 1) Development of new bearing materials Although there remains a problem of cost for ceramic materials which satisfy requirements for bearing materials (lightweight, high load capacity), it is possible that they might play a huge role as the next generation bearing material. As for new materials other than ceramics, at the current stage, research is being conducted on boron and titanium alloys. These alloys have possibility to be practically used widely in a limited range of application. But it will take time before these materials are applicable to bearing steel. 2) Development of bearing surface treatment Development of effective surface treatment required unlimitedly for reduction of rolling friction as well as energy savings, higher speeds rotation and application in special environments such as super-vacuum and super-clean environments is expected. 3) Development of bearing lubricants Development of bearing lubricants is an important theme for improving performance of rolling bearings. The bearing industry is waiting for development and expanded application of biodegradable lubricants that contribute to further reduction of rolling friction and can be returned to the natural environment when spent. 4) Non-contact bearings Non-contact bearings are an effective means of achieving high rotation precision while avoiding noise and reducing friction, which are themes of rolling bearings. Magnetic bearings levitate the shaft by controlling the attraction of the electromagnet, and can be rotated without contract by the equipped motor. Magnetic bearings feature super-high speed, low noise (low vibration), no lubrication (can be used in a vacuum), and extended life. They are monitored and diagnosed by built-in sensor and switching to digital control. Linked with progress in IT technology, application has expanded to turbomolecular pumps and fluid machinery. Fluid bearings are divided into static pressure bearings and dynamic pressure bearings. There is however a recent tendency to expand application of dynamic pressure bearings that are advantageous for compact design. Taking advantage of low noise and high rotation precision features, the bearings are applied to high speed/precision motors for information equipment. Dynamic pressure foil bearings using air as a lubricant fluid have in particular gained notice under high temperature/speed conditions. These non-contact bearings are used in advanced fields where rolling bearings are not applicable, and their applications are currently expanding. 5) Switch to units and modules Taken up as a theme by the automobile industry several years ago, the switch to units and modules is now expanding to industry at large. This contributes to reduction of size and weight, and is a theme that bearing makers must deal with in order to increase added value to bearings. This will probably require not only design and manufacturing technologies related to bearings, but accumulation of technical know-how and continuous improvement including peripheral parts as well. 6) Reform in development efficiency through IT As was previously mentioned, IT innovation technology progresses at an extremely high speed and the product cycle is short. It is hopeless for manufacturers to keep up with this change with only improvement activities. Front loaded restructuring from development to production is required. One of these is to attempt to reduce the development period to 1/2 including trial of each product by the three elemental functions of sharing technical data, reforming the work process and reforming the design environment by introducing 3D CAD. 3. Transition of Bearing Technology 3. 1 Design Technology A half a century has passed since basic bearing life theory using statistics was established. During this time, a discrepancy gradually began to develop between calculated life and actual life. Under the circumstances, adoption of compensation coefficients such as the life adjustment factors for operating conditions and rating coefficient (bm) had to be standardized. In recent years new ideas such as life theory concerning fatigue 24 KOYO Engineering Journal English Edition No.159E (2001)

3 life have come to be discussed. These were made possible by progress in bearing engineering, especially striking progress in material technology, production technology and quality control. The function of bearings is to support a shaft. Digressing into the finer points, the function of bearings is to q support larger loads and offer longer life and w to realize faster smoother rotation. It would not be an overstatement to say the pursuit of these is the history of bearings. We shall now turn our attention to approach measures concerning individual characteristics from the aspect of design. First the approach of design in order to obtain longer life is some ideas concerning rolling raceway. 1) Basic dynamic load rating Basic dynamic load rating of rolling bearings is established by public standards such as ISO291 and JIS B1518. Load rating can be particularly enhanced by increasing the number of rolling elements or the diameter of rolling element. By doing so, basic load rating can be improved 20 to 25% with the same dimensions, and rolling life can be expected to be doubled (see Table 1). Series have already been established for these: R type deep groove ball bearings, maximum type, and JR type tapered roller bearings. The bearings are used for a variety of applications. However such approach of further design changes seemed to be limited now. 2) Profile of rolling surface for a rolling bearing Line contact is made between the rolling elements and raceway and misalignment is produced by moment. This causes contact pressure to become uneven, producing socalled "edge load", whereby contact pressure increases locally. Flaking tends to be caused on edge load area. In order to prevent this, the ideal profile of raceway where the contact pressure distribution becomes uniform is determined corresponding with the load applied to the bearing and the raceway is machined accordingly. In this case, however, profile differs according to the load conditions, so it is necessary to standardize the profile for each application. 3) Double curvature As for ball bearings when contact ellipse between the inner/outer rings and rolling elements overrides from the outer diameter of the inner ring and inner diameter of the outer ring due to inner/outer ring relative misalignment as well that contact pressure increases sometimes resulting in causing flaking. In order to prevent this, a double curvature is used whereby the curvature of the rolling surface of the rolling elements is increased or reduced, the curvature near the rolling surface is reduced, and the area near the inner ring outer diameter (or outer ring inner diameter) is increased. Secondly, the following measures are being taken as an approach to faster rotation. 4) Combination of raceway profiles of rolling bearings The LFT-2 bearing (Low Friction Torque) achieves approximately 40% lower torque than conventional bearings through superfinished rolling surface for tapered rolling bearings and combination of suitable shapes for outer ring rolling surface, inner ring rolling surface, and rolling end face. 5) Suitable rolling element diameter, number of rolling elements, and curvature of ball bearings In order to reduce centrifugal force of rolling elements due to high-speed rotation such as KOYO's ACH and ACT series of angular contact ball bearings, the bearings are designed with smaller size rolling elements, larger curvature and larger number of rolling elements to improve rigidity. The means of approaching from the aspect of main design has already been mentioned, but the means of obtaining longer life and faster rotation are mutually opposed, so it is difficult to satisfy two requirements. The function of bearing required for their applications must be grasped clearly and appropriate design should be selected in correspond to each application Prospects of Bearings for Each Application Bearing needs steadily continue to become more diverse, but various methods and technologies have been developed according to bearing application in order to respond to those needs. Here, technologies for coping with the various applications, current efforts and future prospects are described Automobile Industry The Third Conference of Parties to the Framework Convention on Climate Change (COP3) was held in Kyoto in December 1997, at which it was agreed upon that advanced countries of the world would reduce greenhouse gases by 6% of the 1990 level by the year In order to contribute to prevention of global warming, automobile manufacturers in various countries have subsequently come up with ways to popularize fuel-efficient, low emission vehicles, and continue to be engaged in fierce technological competition. Environment and low energy consumption are the most important keywords for automobile development and technology, and the trend will probably continue. This paper provides a brief description of future prospects for automobile bearings, Koyo's chief products, which themselves are environmental/energy-savings technology. Table 1 Examples of increased basic dynamic load rating a Examples of increased rolling element diameter Bearing Dimensions Basic dynamic Rolling element Rolling element load rating ratio diameter ratio number ratio 6205 φ 25 φ KN (1) R φ 25 φ KN (1.25) s Examples of increased number of rolling elements Bearing Dimensions Basic dynamic load rating Rolling element diameter Rolling element number 30205J φ25 φ KN (1) JR φ25 φ KN (1.16) KOYO Engineering Journal English Edition No.159E (2001) 25

4 1) Automobile engine accessories Along with lower automobile fuel consumption and higher performance, running conditions for engine accessory bearings have become severer, and the bearings must offer durability and ability to rotate at high speeds, while being lightweight, thin and compact (see Table 2). 2) Automobile drive trains While low fuel consumption and reduced weight are demanded for this field, larger power is also demanded. In other words, it is necessary to simultaneously realize opposing needs for high output and compactness/reduced weight. Longer life, lower friction, compactness/reduced weight, and unit construction are demanded of bearings (see Table 3). Fig. 2 Stamped steel rocker arm Fig. 3 Alternator pulley with built-in one-way clutch Table 2 Prospects for automobile engine accessories Fig. 4 Continuous variable accessory drive unit History of development (since 1984) Current status Future prospects (after 5 ~ 10 years) 1980 : High-speed alternator bearing (150 C, <Ball bearings for alternators> Early raceway flaking along with fatigue layer caused by Higher speed, more compact, higher reliability. min 1 ) dispersion/coagulation of carbon by high stress, which is called Starter alternator used instead of 1980 : Polyamide resin idler pulley 1980 : Rolling rocker arm bearing 1985 : Water pump bearing W.E.A, explained and countered by material heat treatment and a new grease. Super-high temperature (200 C) alternator bearing, with a new cage and new grease developed and made practical. Ceramic bearing now being developed. conventional alternator in some cases. Requires higher capacity along with high temperatures and high speeds performance. Switch to ceramic bearing. with triple lip seal 1997 : RM seal 1998 : Phenollic resin idler pulley 1999 : Super-high temperature <Needle roller bearings> Rolling rocker arm used for converting from rotation by camshaft to reciprocating motion. Stamped arm developed for lower weight (Fig. 2). Unit components now being developed. <Idler> Special materials used for further weight reduction. Resin pulleys widely used. alternator bearing Tendency to use chains for engine timing belts and serpentines More compactness requires bearing (200 C, min 1 ) 1999 : Accessory belt autotensioner for accessory belts. Increased demand for accessory belt idler pulleys. Flaking produced along with "white layer" due to severe vibration for accessory belt idlers and countermeasures expanded. pulley that can withstand high-speed rotation ( min 1 ). <Belt systems> Along with facilitated mounting, reduced weight, elimination of maintenance works, and expansion of serpentine belt system: q Development of auto-tensioner that provides constant tension. w Alternator pulley with a built-in one-way clutch (see Fig. 3). Optimal design by belt system analysis. High function products (variable, etc.) compatible with Stop & Go system. e Accumulation of belt system analysis technology. <Continuous variable accessory drive> Pursuit of reduced weight and economical For required output increase of alternator by increasing specifications. electronic components and expanding use of power steering, Expanded applications of continuous accessory rotation speed made independent from engine rotation variable accessory drives. speed, accessory rotation speed change system that rotation speed ratio between accessory and engine can be shifted freely is required. Continuous variable accessory drive that can use V-rib belt drive system developed (see Fig. 4). 26 KOYO Engineering Journal English Edition No.159E (2001)

5 Table 3 Prospects for automobile drive trains 1983 : LFT bearing 1992 : KE bearing 1994 : LFTII bearing 2000 : LC bearing (Long life) 2000 : DRC <Rolling bearings> Increased need for reduced fuel consumption, higher output, more compact size/reduced weight Extended life: Special heat treatment, raceway profile Lower friction: LFT Lightweight, More compact, Unit products <DRC> Direct release cylinder (DRC) that incorporates a bearing and release cylinder in one part developed as a manual transmission clutch release (see Fig. 5). <CVT> Metal belt CVT: Special curvature ball bearing Toroidal CVT developing More improvement in AT/MT Best design by improving remaining life estimation precision. Shortening development periods by CAE. More advanced vibration analysis simulation technology Technology to cope with high temperatures and speeds by increase in EVs Tie-in with work system by built-in sensors, etc. Popularization of CVT Longer life, more compact Notes AT: Automatic transmission MT: Manual transmission CAE: Computer aided engineering EV: Electric vehicle CVT: Continuous variable transmission DRC: Direct release cylinder Table 4 Prospects for automobile chassis History of development 1998 : Hub unit with builtin ABS sensor 1999 : Corner module assembly Current status 2nd and 3rd generation hub units (Fig. 6) are mainly used for non driven wheels and most 3rd generation hub units are the type with a built-in ABS sensor (ABS sensor changed from passive type to active type). 1st generation is mainly used for a driven wheel. 3rd generation is gradually used in Europe and U.S.A. The inner ring of the 3rd generation that was fastened by a nut has been improved by fastening system using orbital forming to reduce weight and improve performance. Reduction of run out of hub flange with improved braking performance (10 µm). Future prospects (after 5 ~ 10 years) Change to module and integration (see Fig. 7) 1st generation 2nd generation 3rd generation Fig. 6 Transition in hub units Fig. 5 Direct release cylinder 3) Automobile chassis There is a growing trend in the automobile part industry to deliver products whereby single parts have been switched to units, modules and systems. In particular western part makers have solidified their position as system suppliers through tieups and M&A, and the number of part makers aiming to become giant part makers is increasing. Unit products with bearing technology, tribological technology, precision machining technology, and electronics technology as cores are in demand (see Table 4). Dust cover Knuckle Disc Hub unit Fig. 7 Axle Assembly KOYO Engineering Journal English Edition No.159E (2001) 27

6 Industrial Machinery 1) General industrial machinery Just like in other industries, there is a demand for the field of general industrial machinery to switch from placing emphasis on improving productivity, cutting cost and maintaining high product quality through mass production to an industrial structure that places emphasis on environmental conservation. Bearings for general industrial machinery may be able to contribute by saving energy, reducing weight and eliminating the need for maintenance (see Table 5). 2) Electronic equipment Digital equipment has made rapid progress on a global scale. Everything from office equipment and household information equipment such as televisions and video recorders, not to mention telecommunication equipment, is switching to digital. Required memory capacity for such equipment tends to increase daily, and high speed rotation, high precision, low noise, low torque, long life, compactness and reduced weight are required of bearing for electronic equipment (see Table 6). 3) Aircraft Aircraft requires particularly high performance and reliability. Bearings must be able to rotate under the harshest operating conditions. The bearings must be able to withstand temperatures as high as 300 C without dimension change or softening, must be durable after lubrication is blocked out (dry run), and must run without seizure even if the fitting or load fluctuates due to change in temperature or direction of gravity (see Table 7). Table 5 Prospects for general industrial machinery <Bearings for rolling stocks> 1991 : Cylindrical roller bearing with rib for 300 series bullet train 1996 : Grease-packed double row tapered roller bearing for 500 series bullet train <Bearings for rolling mill> 1984 : World's first modified thick plate mil BUR bearing <Other industrial machinery> 1994 : Slewing rim bearing for superlarge (7.2 m) tunnel boring machine 1999 : Bearing for large optical ultrared ray telescope Subaru Max. vehicle speed: 300 km/h Maintenance period: km Switch from plain bearings to rolling bearings Switch to sealed bearings Extended maintenance/ inspection period Higher function due to switch to unit Maintenance period: 2.4 million km Maintaining bearing system cleanliness, preventing lubricating grease deterioration, development of low torque seal System for monitoring vehicle shaft speed and temperature to be made practical and establishment of preventative safety Linear motor car to be made practical Challenge to achieve 500 km/h Contribution to rolling mill facilities compactness and easy maintenance Development of long life, rustproof materials, establishment of lubrication system for enhancing seal and lubricating performance Thinner bearings Development of maintenance-free bearing and establishment of predictive maintenance technology by bearing with abnormality monitoring function Low-cost, throw-away bearing 1979 : Bearing for video recorder 1983 : Compact one-way clutch 1985 : Ball bearing for fan motor 1991 : Ball bearing for HDD spindle 1995 : SGB for HDD 1997 : One-way clutch with built-in ball bearing 1997 : Compact one-way clutch with built-in ON-OFF mechanism 1998 : Ceramic bearing for HDD spindle Table 6 Prospects for electric equipment <HDD bearing> Memory capacity 10 ~ 20 GB/disk, NRRO 60 nm Rolling elements: Steel, ceramics NRRO, nm 120 NRRO transition Notes NRRO: Non Repeatable Run Out HDD: Hard Disk Drive SGB: Spiral Groove Bearing HDD basic function, high surface density by higher head performance, low noise, low current, speed improvement, 70 ~ 140 GB/disc to be realized NRRO 1/4 New ceramic material used for rolling elements Development of low noise bearing, new grease Switch to SGB due to limitation of ball bearings AV market Higher density, lower noise SGB in mainstream Low class: Ball bearings continue to be used. High class (for server): Ceramic bearings 28 KOYO Engineering Journal English Edition No.159E (2001)

7 4) Machine tools Requirements for bearings to be used in machine tools include high rotational precision, high rigidity, high speed rotation, high output, low noise, and long life, among which high speed rotation is most emphasized because it largely affects machine efficiency (see Table 8). 5) Extreme special environments Bearings for extreme special environments are primarily used in the semiconductor/liquid crystal, electronic component, vacuum equipment, food/pharmaceuticals and chemical industries. Along with remarkable technological progress in these industries, the used environment for rolling bearings will probably continue to become harsher and more diversified year by year. The semiconductor/liquid crystal industry, which will probably be a driving force behind industry of the 21st century, will require diverse performance including vacuum, corrosion resistance, high temperature, as well as low dusting, high load and non-magnetism (see Table 9). Table 7 Prospects for aircrafts 1979 : Domestic development of elliptical orbit bearing through technical tieup with ITI of U.S : Domestic development of aluminum alloy slewing rim bearing for turrets Award from Defense Equipment Association 1989 : Award from Defense Equipment Association for development of special grease lubricated bearing for compact jet engines 1989 : Ceramic bearings applied to jet engines (developed in cooperation with IHI and Toshiba) 1996 : First domestic development of swash plate bearing for OH-1 helicopter for pure domestic development <Concerning bearings for jet engines for aircraft> High speed: Ball bearing dn value 2.0 ~ Roller bearing dn value ~ Temperature: 200 ~ 300 C Bearing materials: a Heat-resistant steel: M50 (VIM- VAR) s Heat-resistant carbonizing steel: M50NiL Ceramic material: Hybrid ceramic bearing with silicon nitride (Si 3 N 4 ) rolling elements made practical Lubricant: Oil lubrication at 300 C Bearing type: Rolling bearing <Concerning bearings for jet engines for aircraft> High speed: Ball bearing dn value 2.5 ~ Rolling bearing dn value ~ Temperature: 300 ~ 350 C Bearing materials: Improvement of heat and wear resistance, high fracture toughness value (K IC ) that can withstand circumference stress when rotating at high speed Ceramic materials to be made practical by partial application of silicon nitride Lubricant: Oil lubrication at 300 C Bearing type: Primarily rolling bearings, but some hydrodynamic (foil) bearings and magnetic bearings Achievement of dn value : Development of new materials, heat treatment technology, surface treatment, lubricant; progress in design technology and verification technology (Advancement of simulation technology and verification test technology. construction of service system and bearing with self-diagnosis function [module] ) Table 8 Prospects for machine tools 1981 : Super high speed tapered roller bearing (HA type) 1982 : Oil/air lubrication equipment 1984 : Ball screw support bearing 1984 : Ceramic bearing (rolling elements made of silicon nitride) 1985 : High speed angular ball bearing ACH series 1985 : Ball screw Support bearing unit 1989 : Angular ball bearing with plastic cage 1990 : Cylindrical roller bearing with plastic cage 1992 : Angular bearing with outer ring oil hole/groove 1996 : Raceway direct oil supply bearing 2000 : High performance bearing High Ability series Higher speed Large contribution of development of ceramic bearing Minimal oil supply oil/air lubrication method also effective Jet lubrication bearing; raceway direct oil supply bearing made practical Development of fixed position preload switching technology Practical level of machine tool bearing Grease lubrication dn : Oil/air lubrication dn : Jet lubrication dn : Higher speed Development of high speed, long life grease Development of centrifugal force destruction countermeasures technology Bearing with sensor for self-diagnosis system Popularization of preload switching system same as above Estimated practical level of machine tool main shaft Grease lubrication dn : Oil/air lubrication dn : Jet lubrication dn : Progress in technology development for new fields q Development of bearing element technology for micro machine spindle. w Magnetic bearing for machine tool in clean environment KOYO Engineering Journal English Edition No.159E (2001) 29

8 Table 9 Prospects for extreme special environments 1984 : Ceramic bearing (silicon nitride) 1986 : Non-lubricated clean bearing (high hardness carbon balls) 1990 : Low particle emission bearing (PTFE coating) 1992 : Low particle emission bearing for high temperatures 1994 : Corrosion resistant ceramic bearing 1996 : Low particle emission clean pro bearing 1998 : Clean pro bearing for high temperatures 2000 : High temperature/high load solid lubricant bearing Non-magnetic steel bearing High speed rotation, non-magnetism, insulation performance and can be used in clean, vacuum, corrosive or high temperature environments Inner ring, rolling element material: Stainless steel, ceramics, tool steel Cage material: Stainless steel, fluorine resin, PEEK resin, graphite Solid lubricant (processing for rolling elements and cages): Applied to lead and silver ion plating Coating such as PTFE and special fluorine high polymer molybdenum disulfide Development of high performance products along with severe environments such as clean, vacuum, corrosive and high temperature Development of high performance products along with required performance of high speed rotation, non-magnetism, and insulation Development of high load/rigidity products along with larger extreme special environment equipment Development of unit products and modules Bearings for super clean environments Bearings for super vacuums 4. Conclusion Along with satisfying customer needs for more diversified, more advanced bearings, Koyo would continue to develop products considering the preservation of the global environment and LCA (life cycle assessment), if pressed to say, for the continued existence of mankind as well. Koyo hopes to contribute to the world by continuing to provide the rolling bearings demanded by the society. References 1) M. Okada: Tribologist (Journal of Japanese Society of Tribologists) 45, 11 (2000) 2. 2) H. Kato: RICOH Solution Seminar ( ) "IT kakumei to nippon keizai no michi" 30 KOYO Engineering Journal English Edition No.159E (2001)