FOR EXTREME SPECIAL ENVIRONMENTS BEARINGS

Japan Quality

CAT. NO. B1013E Ceramic Development Story Introduction to Application Examples

1 tools 3 World’s first successful practical application of ceramic bearings 2 Film manufacturing equipment 3,4 3 Power generation equipment 4 4 Industrial furnaces 5,6 “Aren’t there any bearings that can be used in seawater?” 5 Production equipment 7,8

…One of our customers asked this question, 6 Semiconductor manufacturing equipment 9,10,11 7 Motor, Industrial machinery 12 triggering our efforts to develop the ceramic bearing. 8 Medical equipment 13

Initially, we attempted to use alumina as the raw material, 9 Home electrical appliances 13,14 but it split quickly and cracks developed… 10 Outer space, Leisure 14 11 Automobiles, Motorcycles 15,16 Following this, research stalled and ended after approximately five years.

Research resumed again in 1978; Features this time with the development team consisting of five members. Cooperation Properties of ceramic materials

Additionally, a material manufacturer known for 1 Material characteristics 17 leading research was invited to join the effort. 2 Rolling fatigue of ceramic materials 18 3 Ceramic materials suitable for rolling bearings 19 Starting with as the raw material, 4 Composition of ceramic bearings 19 strength was reinforced using a sintering additive and a hot pressing process eliminated cracking. As a result, the first ceramic bearings were commercialized in 1984. Production Process

Some of our customers had doubts about strength in the beginning, Ceramics Production Process stating “If ceramic cracks, it will surely split in two!” 1 Production Process 20

At that time, customers would hit the bearings with a hammer to test their strength. Product Details Doing this, the concrete below the bearing was the only thing that cracked! Ceramic Bearing Product Details Finding practical applications was initially difficult, 1 Rolling fatigue life of ceramic bearings 21 but their strength and high-speed performance were gradually recognized, and Good! ceramic bearings began to be utilized for the main spindles of machine tools. 2 Static load rating of ceramic bearings 22 3 Impact strength of ceramic bearings 23

Next, they began receiving attention from semiconductor manufacturers owing to the 4 Fitting of ceramic bearings 24 characteristics of not using oil and not producing waste.

Ceramic bearings were then utilized in a section of experimental equipment on the Performance expanding their range of applications. space shuttle Colombia, Ceramic Bearing Capacities

As productivity improved, ceramic bearings began being used in the 1 Corrosion resistance 25,26 mass production of computer HDDs and automobile engines. 2 Non-magnetic performance 26 3 Insulation 27 Their excellent performance has been recognized and Koyo 4 High-speed performance 28 applications have received various awards, such as the Japan Fine Ceramics Award.

And now… Product Introduction

1 Ceramic balls 29 “For ceramic bearings, the answer is KOYO”

1 2 Introduction to Application Examples CERAMIC BEARINGS 1 Machine tools

CERAMIC BEARINGS

High High Vacuum Clean Photographic Film Vacuum Clean temperature temperature 1 Spindle (Angular Contact Ball Bearing) Product : Hybrid Ceramic Bearings 2 Manufaturing Equipment Product: Hybrid Ceramic Bearings (with special features) Electric Magnetic Electric Magnetic Corrosive Corrosive Machine tool spindle bearings are required to have superior rotational performance at extremely high speeds, quick field field A photographic film production line treats film surfaces by applying a high voltage. field field acceleration/ deceleration, high rigidity, and reduced temperature rises. Hybrid Ceramic Bearings are widely used in such environments, because the ceramic inner ring and balls serve as insulators. Hybrid Ceramic Bearings, which satisfy these requirements, are widely used in this application. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● 20% to 30% reduction in temperature rise ● Insulation under high voltage environments ● Upper limit of rotational speed range is 1.2-1.5 times higher (compared to Koyo steel bearings)

Use Conditions Use Conditions High voltage Rotational speed: 25 000 min−1 Rotational speed: 200 min−1 6 （ d mn ＝ 2.75 × 10 ） Temperature: Room temp. Lubrication: Oil or Grease Lubrication: Grease Spindle power: 75 kW

High Vacuum Clean 2 Spindle (Cylindrical Roller Bearing) Product : Hybrid Ceramic Bearings temperature 3 Power generation equipment Electric Magnetic Corrosive Seizure resistance performance under unbalanced load conditions due to misalignment improved at the Vertical Spindle field field Machining Center. CERAMIC BEARINGS Abrasion High speed Low torque resistance

High Vacuum Clean ● 20% to 30% reduction in temperature rise 1 Wind Turbine Generator Product: Hybrid Ceramic Bearings temperature ● Upper limit of rotational speed range is Electric Magnetic Corrosive 1.2-1.5 times higher Wind Turbine Generator are strongly required to operate for extensive periods of time without the need of maintenance. field field However, bearings used in generators are subject to electrical pitting, which may cause the bearings to break down. (compared to Koyo steel bearings) Hybrid Ceramic Bearings, which have superior durability and reliability, are widely used in such aerogenerators. Abrasion High speed Low torque resistance Use Conditions Rotational speed: 12 000 min−1 Lubrication: Grease ● Prevention of electrical pitting ● Extension of grease service life (three times longer than Koyo steel bearings)

Use Conditions Rotational speed: 2700 min−1 Temperature: Below freezing point to 2 Film manufacturing equipment approx. 60°C Lubrication: Grease

CERAMIC BEARINGS

High High Liquid Crystal Polarizing Film Vacuum Clean Vacuum Clean temperature temperature 1 Manufacturing Equipment Product : Corrosion Resistant Hybrid Ceramic Bearings 2 Micro Gas Turbine Generator Product: Hybrid Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive Liquid crystal polarizing film manufacturing equipment use acid solution, alkaline solution, dying solution, distilled water, field field The world's smallest gas turbine generators emit clean exhaust emissions and hence are friendly to the environment. field field and other solutions. Hybrid Ceramic Bearings are used in these generators because they are low in vibration and noise generation, and have In such corrosive environments, Corrosion Resistant Hybrid Ceramic Bearings are widely used. Abrasion excellent high speed performance. Abrasion High speed Low torque High speed Low torque resistance resistance

● Corrosion resistance to solutions such as acid ● Improved reliability in high speed rotation Turbine solution, alkaline solution, dying solution, Ball bearings Generator rotor Film coil Film rewinding coil and distilled water Generator stator

Use Conditions Use Conditions Rotational speed: 80 min−1 Rotational speed: 10 000 min−1 6 Temperature: Room temp. to 80°C （ d mn ＝ 2.22 × 10 ） Ball bearing Lubrication: Chemical solution Temperature: 200°C Chemical solution Ball bearing Lubrication: Oil

3 4 Introduction to Application Examples CERAMIC BEARINGS 4 Industrial furnaces

CERAMIC BEARINGS

High High Liquid Crystal Panel Bonding and Vacuum Clean Vacuum Clean temperature temperature 1 LC Sealing Furnace Product : Hybrid Ceramic Linear Motion Ball Bearings 4 Tube Annealing Furnace Guide Rolls Product: Hybrid Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive Substrate bonding press jigs for use in furnaces must be low in particle emissions and have a long service life under high field field The guide roll bearings installed inside tube annealing furnaces are used under high temperatures without lubrication. field field temperature conditions. Hybrid Ceramic Bearings are suitable for such applications. The Clean Pro Hybrid Ceramic Linear Motion Ball Bearings are widely used for such jigs. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Suitable for clean environments thanks Liquid crystal panel press jig ● Compatible with high temperature environments Guide roller (ceramic) to low particle emissions

Bearing

Use Conditions Use Conditions Stroke speed: 5 mm/s Rotational speed: 300 min−1 Temperature: 200°C Temperature: 300°C Ambient pressure: Normal pressure Lubrication: Clean pro coating Liquid crystal panel Linear motion ball bearings

High High Vacuum Clean Vacuum Clean 2 Furnaces Cars Product: High Temperature Hybrid Ceramic Bearings temperature 5 Diffusion Furnace Dolly Product: Full-complement Ceramic Ball Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive The bogies, conveyers and other carrier systems used in furnaces are exposed to high temperatures. field field Conditions in a diffusion furnace are harsh, including not only high temperature, but also corrosive gas. field field Because of their high heat resistance, High Temperature Hybrid Ceramic Bearings are used in such applications. Incorporating a rolling mechanism for the conveyor dolly in the furnace enables smooth conveyance to be obtained, thereby Abrasion leading to improvements in product quality and productivity. Abrasion High speed Low torque High speed Low torque resistance resistance

● Applicable to high temperature environments ● Compatible with high-temperature environments ● Corrosion-resistant against corrosive gases ● Contributes to improved productivity

Use Conditions Use Conditions Rotational speed: 10 to 500 min−1 Temperature: 800°C or higher Temperature: 500°C Ambient pressure: Corrosive gas atmosphere Lubrication: Graphite Load: 5N

High Vacuum Clean 3 Baking Furnace Cars Product: High Temperature Hybrid Ceramic Bearings temperature Electric Magnetic Corrosive In the kiln that bakes fluorine resin onto the heat rollers of copying , conveyor bearings must be low in particle field field emissions under high temperatures. Because it is structurally difficult to mount bearings accurately, High temperature Hybrid Ceramic Bearings are used for this application, along with aligning rings. Abrasion High speed Low torque resistance

● Compatible with high temperature environments

Use Conditions Rotational speed: 3 to 10 min−1 Temperature: 400 to 500°C Lubrication: Graphite

5 6 Introduction to Application Examples CERAMIC BEARINGS 5 Production equipment

CERAMIC BEARINGS

High High Aluminum Electrolytic Capacitor Vacuum Clean Vacuum Clean temperature temperature 1 Manufacturing Equipment Product: High Corrosion Resistant Ceramic Bearings 4 Steel Wire Stranding Machine Product: Hybrid Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive In an aluminum foil electrolytic capacitor manufacturing equipment, a strong acid solution is used to treat the aluminum foils. field field Steel wires for radial tires are produced by stranding steel wires to attain the required strength. In steel wire stranding field field High Corrosion Resistant Ceramic Bearings are widely used in such highly corrosive environments. machines, which involve high speed rotation, Hybrid Ceramic Bearings are used for improved service life and stability. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Corrosion resistance to strong acid solution Roller ● Reduced temperature rises Ball bearings Ball bearings Aluminum foil ● Reliable durability

Chemical solution Use Conditions (Hydrochloric acid Use Conditions Rotational speed: 50 min−1 or sulfuric acid) Rotational speed: 6 000 min−1 or higher Spindle Spindle Temperature: 90°C Lubrication: Grease Lubrication: Chemical solution (hydrochloric acid and sulfuric acid) Roller Wire stranding section

High High Synthetic Fiber Vacuum Clean Vacuum Clean temperature temperature 2 Manufacturing Equipment Product: Corrosion Resistant Hybrid Ceramic Bearings 5 Jet Electrostatic Coating Machine Product: Hybrid Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive Acid solution, alkaline solution, water, and other liquids are used in synthetic fiber yarn reinforcing processes. Corrosion field field In a jet electrostatic coating machine, grease may escape from the spray nozzle due to the air motor, affecting the quality of field field Resistant Hybrid Ceramic Bearings are applied in such corrosive environments. the paint to be coated. Abrasion To resolve this problem, Hybrid Ceramic Bearings that do not use grease are used. Abrasion High speed Low torque High speed Low torque resistance resistance

● Corrosion resistance under acid solution, ● Prevention of grease scattering Yarn alkaline solution and water ● Prevention of paint contamination

Electrostatic coating spray Use Conditions Use Conditions nozzle Rotational speed: 20 to 100 min−1 Rotational speed: 20 000 min−1 Chemical Temperature: Room temp. to 90°C solution Lubrication: Fluorine polyme Bell-like structure view Lubrication: Chemical solution Roller

High High Vacuum Clean Vacuum Clean 3 DVD Sputtering Equipment Product: Hybrid Ceramic Bearings temperature 6 Blister Packaging Equipment Product: High-temperature Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive To improve reliability further, Hybrid Ceramic Bearings are used. field field As heater roll bearings used in processing reach high temperatures during operation, conventional bearings are quickly field field damaged. Abrasion Incorporating high-temperature ceramic bearings extends the bearing replacement cycle and improves productivity. Abrasion High speed Low torque High speed Low torque resistance resistance

● Insulation ● Applicable to high-temperature environments ● Contributes to improved productivity Heater roll

Use Conditions Use Conditions Rotational speed: 300 min−1 Temperature: 250°C Temperature: Room temp. Load: 900N Lubrication: Grease Lubrication: Grease

7 8 Introduction to Application Examples CERAMIC BEARINGS 6 Semiconductor manufacturing equipment

CERAMIC BEARINGS

High High Transfer Robot for Semiconductor Vacuum Clean Vacuum Clean temperature temperature 1 and LCD Manufacturing Equipment Product: K Series Full-Complement Hybrid Ceramic Ball Bearings 4 Etching Equipment Product: Hybrid Ceramic Bearings (with special features) Electric Magnetic Electric Magnetic Corrosive Corrosive For application in transfer robots for semiconductor and liquid crystal manufacturing equipment, bearings are required to be field field Bearings used in etching machines must be resistant to halogen, hydrofluoric acid, and other corrosive gasses, as well as field field low in particle emissions and have a long service life. low in particle emissions. To meet these requirements, PTFE coated Hybrid Ceramic Bearings are used. Bearings may be delivered incorporated in arm units for improved assemblability and maintainability. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Applicable to vacuum environments and ● Resistant to corrosive ambient gases such as

clean environments halogen and hydrofluoric acid Bearings

● Optimal for machine size reduction ● Suitable for clean environments thanks to low Preparatory chamber particle emissions

Use Conditions Use Conditions

Temperature: Room temp. to 200°C Temperature: Room temp. to 60°C Reaction chamber Ambient pressure: 10−3 Pa Ambient pressure: Normal to 10−2 Pa Lubrication: Grease or clean pro coating Bearing unit for application to transfer robots Load: Radial load of 10 N Arms Lubrication: PTFE coating Door

High High Vacuum Clean Vacuum Clean 2 Electron Beam Lithography Product: Non-magnetic Hybrid Ceramic Bearings temperature 5 Vacuum Evaporator Product: High Temperature Hybrid Ceramic Bearings (with special features) temperature Electric Magnetic Electric Magnetic Corrosive Corrosive The bearings in semiconductor production electron beam lithography are exposed to strong magnetic fields. field field Bearings used in the planetary section of vacuum evaporator are required to be high in durability under high temperatures, field field Because of their non-magnetic characteristics, Hybrid Ceramic Bearings are used in such machines. high load (moment) conditions. To ensure a long bearing life under high temperature conditions, High temperature Hybrid Abrasion Ceramic Bearings with special features are used. Abrasion High speed Low torque High speed Low torque resistance resistance

● Compatible with vacuum, strong magnetic ● Improved reliability in vacuum and field environments high temperature environments

Use Conditions Use Conditions Rotational speed: 100 min−1 Rotational speed: 1 to 30 min−1 Temperature: Room temp. Temperature: 200 to 400°C Ambient pressure: 10−5 Pa Ambient pressure: 10−6 to 10−8 Pa Vibration plate mounting jig Lubrication: Grease Lubrication: Molybdenum disulfide or silver

High High Gates in Chemical Vapor Vacuum Clean Spin-dryer for Wafer Cleaning Vacuum Clean temperature temperature 3 Deposition Equipment Product: Hybrid Ceramic Ball Bearing Clean Pro Linear Motion Ball Bearings 6 Equipment Product: Corrosion Resistant Hybrid Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive Hybrid Ceramic Ball Bearings and Clean Pro Linear Motion Ball Bearings are widely used for the doors of the chemical vapor field field In semiconductor wafer cleaning processes, wafers are cleaned in cleansing chemicals, rinsing liquids, distilled water, and field field deposition (CVD) equipment. other liquids before drying. Abrasion Because of their high corrosion resistance, Corrosion Resistant Hybrid Ceramic Bearings are widely used in wafer cleaners. Abrasion High speed Low torque High speed Low torque resistance resistance

● Applicable to high temperature, vacuum and Linear motion ball bearings ● Corrosion resistance to solutions such as clean environments Motor cleaning chemicals, rinsing liquids, and Container distilled water HEPA filter Flywheel Bearing Exhaust Container Flywheel Deep groove Door Use Conditions Use Conditions ball bearing Rotational speed: 10 to 200 min−1 Rotational speed: 2 000 to 3 000 min−1 Temperature: 200°C Temperature: Room temp. Exhaust Ambient pressure: Normal to 10−4 Pa Lubrication: Grease Lubrication: Clean pro coating Deep groove ball bearing

9 10 Introduction to Application Examples CERAMIC BEARINGS 6 Semiconductor manufacturing equipment 7 Motor, Industrial machinery

CERAMIC BEARINGS CERAMIC BEARINGS

High High Vacuum Clean Vacuum Clean 7 Wafer Transfer Equipment Product: Hybrid Ceramic Linear Way Bearing Units (with special features) temperature 1 Polygon Scanner Motor Product: Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive For application in wafer transfer equipment, low particle emissions performance is required. field field Hybrid Ceramic Bearings, which exhibit superior high speed performance, are widely used in high speed polygon scanner field field For such devices, Clean Pro Hybrid Ceramic Linear Way Bearing Units are widely used. motors. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Suitable for clean environments thanks to ● Excellent reliability in high speed rotation

low particle emissions Idler ● Corrosion resistant to cleaning agent splashes

Use Conditions Use Conditions

Driving pulley Driven pulley −1 Stroke speed: 350 mm/s Belt Rotational speed: 26 000 min or higher Temperature: Room temp. Bracket Lubrication: Grease Rail Ambient pressure: Normal pressure Linear way bearing Lubrication: Clean pro coating

High High Wafer Cleaning Equipment for Vacuum Clean Vacuum Clean temperature temperature 8 Chemical Mechanical Polishing System Product: Corrosion Resistant Ceramic Bearings 2 Ultrasonic Motor in Magnetic Resonance Imagers Product: Ceramic Bearings Electric Magnetic Electric Magnetic Corrosive Corrosive In the semiconductor multilayer production process, each wafer surface should be treated to maintain evenness. This field field The motors installed in magnetic resonance imagers (MRI) use magnetism insensitive Ceramic Bearings. field field process uses chemical mechanical polishing equipment, and the cleaner attached to the equipment uses Corrosion Resistant Ceramic Bearings. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Corrosion resistance to corrosive solutions ● Compatible with strong magnetic field environments

Use Conditions Use Conditions Rotational speed: 100 min−1 Rotational speed: 500 min−1 Temperature: Room temp. Temperature: Room temp. Lubrication: Fluorine polymer Lubrication: Grease

High High Vacuum Clean Vacuum Clean 9 Turbo Molecular Pump Product: Full-Complement Hybrid Ceramic Ball Bearings (with special features) temperature 3 Switched Reluctance Motor Product: Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive Magnetic bearings are used in turbo molecular pumps driven at extremely high speeds. To protect the blades from fracture in field field For high speed, high efficiency switched reluctance (SR) motors, which do not use coils or permanent magnets, Hybrid field field case of a power failure or magnetic failure, touchdown bearing units are used. As touchdown bearings, Full-Complement Ceramic Bearings are applied. Hybrid Ceramic Ball Bearings are used to increase the service life of the touchdown bearings under severe hostile conditions. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Improved reliability in vacuum environments ● Excellent reliability in high speed rotation

Use Conditions Use Conditions Rotational speed: 20 000 to 60 000 min−1 Rotational speed: 30 000 min−1 Ambient pressure: 1 Pa Lubrication: Grease Lubrication: Molybdenum disulfide or silver

11 12 Introduction to Application Examples CERAMIC BEARINGS 8 Medical equipment

CERAMIC BEARINGS

High High Vacuum Clean Vacuum Clean 1 Blood Contrifuge Product: Hybrid Ceramic Bearings (with special coating) temperature 2 Fan Motor Product : Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive Corrosion resistance is required of bearings to be used in blood contrifuge especially to physiological saline. field field Bearing defects occur due to electric pitting in various motors. field field Hybrid Ceramic Bearings with bearing rings coated with a corrosion resistant film are suitable for such corrosive environments. Hybrid ceramic bearings are utilized as a measure against electric pitting. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Corrosion resistance to physiological saline High frequency motor ● Prevention of electrical pitting Supernatant Shaft Spherical plain liquid outlet Rotor bearing Ceramic bearing Rotor Use Conditions Mechanical seal Use Conditions Rotational speed: 20 000 min−1 Rotational speed: 5 000 min−1 Temperature: –10 to 10°C Ball bearing & Temperature: –10 to 120°C Spherical plain bearing Lubrication: Grease Bearing mounted section Lubrication: Grease Sample inlet Mechanical seal

High Vacuum Clean 2 Ultrasonic Motor in Magnetic Resonance Imagers Product: Ceramic Bearings temperature 10 Outer space, Leisure Electric Magnetic Corrosive The motors installed in magnetic resonance imagers (MRI) use magnetism insensitive Ceramic Bearings. field field CERAMIC BEARINGS Abrasion High speed Low torque resistance

High Vacuum Clean ● Compatible with strong magnetic field environments 1 Outer Space Experimentation Equipment Product: Ceramic Bearings temperature Electric Magnetic Corrosive Utilized in experimental equipment on a space shuttle. field field Stainless-steel bearings using fresh water as the lubricant experience abrasion and do not reach the required service life. Using general ceramic bearings enables the required service life to be attained. Abrasion High speed Low torque resistance Use Conditions Rotational speed: 500 min−1 Temperature: Room temp. ● Long Service Life under Freshwater Lubricating Conditions Lubrication: Grease

Use Conditions Rotational speed: 10 000 min−1 Temperature: 30°C 9 Home electrical appliances Load: Radial 5N, Axial 10N Lubrication: Fresh water

CERAMIC BEARINGS

High High Vacuum Clean Vacuum Clean 1 Air-conditioner motors Product : Hybrid Ceramic Bearings temperature 2 Inline Skates Product : Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive When using motors equipped with inverter control such as air-conditioner motors, there is a possibility of electric pitting field field Because of their low running torque and high durability, Hybrid Ceramic Bearings are widely used in speed skates. field field defects occurring on motor bearings. Using a ceramic — which is an insulator — as the rolling elements eliminates electric pitting. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● CElectric pitting prevent through insulation performance ● Low torque and improved durability

Use Conditions Use Conditions Rotational speed: 3 000 min−1 Rotational speed: 10 000 min−1 Load (preload): 1.5% C Lubrication: Oil or grease Lubrication: Grease

13 14 Introduction to Application Examples CERAMIC BEARINGS 11 Automobiles, Motorcycles

CERAMIC BEARINGS

High High Vacuum Clean Vacuum Clean 1 Turbocharger Product: Hybrid Ceramic Bearings temperature 4 Rally Car Hub Units Product: Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive Corrosive Bearings supporting the main shaft of the turbocharger are responsive during acceleration and durable when using field field Excellent abrasion resistance even under severe environmental conditions has improved durability and reliability. field field low-viscosity, dirty oil. Hybrid ceramic bearings with superior reliability are utilized. Abrasion Abrasion High speed Low torque High speed Low torque resistance resistance

● Service life three times longer than that ● Utilized in the car entered in the of ordinary bearings Paris-Dakar Rally in 1997 and 1998 ● Acceleration response improved 20% ● Rigidity improved ● Oil quantity reduced 80% ● Unsprung weight reduced

Use Conditions Rotational speed: 180 000 to 210 000 min−1 Temperature: 350°C Lubrication: Oil Photos: Courtesy of Mitsubishi Motors Corporation

High High Vacuum Clean Vacuum Clean 2 Fuel Injection System Control Valve Product: Ceramic Ball temperature 5 Motorcycle Superchargers Product: Hybrid Ceramic Bearings temperature Electric Magnetic Electric Magnetic Corrosive The new superchargers for large motorcycles utilize lightweight, high-strength ceramic balls capable of high-speed rotation. The Corrosive The common rail system (fuel injection system), which enables diesel engines to feature high power, good fuel economy and low field field field field incorporation of ceramic balls has achieved bearings with excellent high-speed performance, heat resistance and abrasion emissions, is equipped with Ceramic Balls in the control valves. resistance. Additionally, when using hybrid ceramic bearings, high output is achieved even for race-specification motors operating Abrasion Abrasion High speed Low torque High speed Low torque resistance under harsh conditions. resistance

● Compatible with high pressure fuel injection thanks to ● High-speed performance, heat resistance

improved wear resistance and seizure resistance Solenoid valve Ceramic ball and abrasion resistance improved ● Contributes to achieving high output supporting race specifications 135 MPa Use Conditions

Maximum pressure: 135 MPa Nozzle

Injection

Photos: Courtesy of Kawasaki Heavy Industries, Ltd.

High Vacuum Clean 3 Wheel Bearings for Solar Cars Product: Hybrid Ceramic Bearings temperature Electric Magnetic Corrosive Stable operation of the motor section under severe open conditions of running eight hours or more per day. Improvements in field field weight reduction, durability and reliability. Suppressing spinning resistance and efficiently transferring the driving force to the wheels contributes to saving power. Abrasion High speed Low torque resistance

● Australia: Covered over 3,000km vertically ● South Africa: Covered over 4,000km

Use Conditions Rotational speed: 1 000 min−1 Lubrication: Grease

Photo: Courtesy of Tokai University

15 16 Features CERAMIC BEARINGS

Properties of ceramic materials

CERAMIC BEARINGS

1 Material characteristics 2 Rolling fatigue of ceramic materials

Table 1 below lists the mechanical and physical properties of major ceramic materials used as bearing materials. Table 2 compares silicon nitride and high carbon The individual ceramic materials were tested for rolling fatigue under oil chromium bearing steel. lubrication and under water lubrication, to evaluate their applicability as bearing material. Figs. 1 and 2 show the results of the tests. The figures indicate that each ceramic material has a certain level of rolling Test conditions Table 1 Mechanical and physical properties of ceramic materials used as bearing materials fatigue strength and that silicon nitride has the highest fatigue strength among Oil lubrication Water lubrication Ceramic Material Silicon Nitride Zirconia Silicon Carbide the ceramic materials tested. Lubricant Spindle oil City water Property Unit Si3N4 ZrO2 SiC Ball Bearing steel Ceramic Density g/cm3 3.2 6.0 3.1 Load Increased in stages at every 1.08 × 10 7 cycles Linear expansion coefficient K－1 3.2×10－6 10.5×10－6 3.9×10－6 Rotational speed 1 200 min－1 Vickers hardness HV 1 500 1 200 2 200 Silicon nitride （Si3N4） Module of longitudinal elasticity GPa 320 220 380 1 250 Zirconia Poisson's ratio 0.29 0.31 0.16 （ZrO2） Three point bending strength MPa 1 100 1 400 500 1 000 1/2 Fracture toughness MPa・m 6 5 4 Test equipment Heat resistance (in atmospheric air) ℃ 800 200 1 000 or higher 750 Thermal shock resistance ℃ 750 or higher 350 350 500 Coefficient of thermal conductivity W/（m・K） 20 3 70 Load (per ball), N Silicon carbide Specific heat J/（kg・K） 680 460 670 （SiC） 250 Lubricant Table 2 Comparison of characteristics of silicon nitride and high carbon chromium bearing steel 0 1.08 2.16 3.24 4.32 5.4 6.48 7.56 8.64 Silicon Nitride High Carbon Chromium Bearing Steel Property Unit Advantages of Ceramic Bearings Stress loading cycles,×10 7 Si3N4 SUJ2 Decrease in centrifugal force induced by rolling elements (balls or rollers) Ball ( 9.525 mm ) Density g/cm3 3.2 7.8 Fig. 1 Comparison in rolling fatigue life under oil lubrication → Longer service life and reduced bearing temperature rises Flat ceramic plate Decreased internal clearance change due to reduced bearing temperature rises Linear expansion coefficient －1 －6 －6 K 3.2×10 12.5×10 → Lowered vibration and reduced preload changes 1 250 Vickers hardness HV 1 500 750 Load Less deformation in rolling contact areas Module of longitudinal elasticity GPa 320 208 → Higher rigidity 1 000 Silicon nitride Poisson's ratio 0.29 0.3 （Si3N4）

Heat resistance ℃ 800 180 Retention of superior load carrying characteristics under high temperature 750 Corrosion resistance High Low Useful in acid or alkaline solutions Test equipment appearance Zirconia Magnetism Non-magnetic Ferromagnetic Decreased rotational fluctuation in ferromagnetic field due to non-magnetization 500 Load (per ball), N （ZrO2） Conductivity insulator conductor Prevents electrical pitting Bond Covalent bond Metallic bond Decrease in adhesion (or material transfer) due to oil film thinning in rolling contact areas 250 Silicon carbide （SiC）

0 1.08 2.16 3.24 4.32 5.4 6.48 7.56 8.64 Stress loading cycles,×10 7

Fig. 2 Comparison in rolling fatigue life under water lubrication

Fig. 3 Rolling fatigue life test conditions and test equipment

17 18 Features Production Processes CERAMIC BEARINGS

Ceramics Production Processes

CERAMIC BEARINGS

3 Ceramic materials suitable for rolling bearings 1 Production processes

Table 3 shows the results of evaluating the ceramic materials in terms of their characteristics and the rolling fatigue strength. Among the ceramic materials tested, With silicon nitride, characteristics such as density and strength can vary greatly depending on the manufacturing method and manufacturing conditions. silicon nitride is the most suitable as rolling bearing material. Therefore, it is necessary to strictly control items such as shape, sintering and other processes when manufacturing silicon nitride for ball and roller bearings. JTEKT uses the silicon nitride produced by the hot isostatic pressing (HIP) method as the standard ceramic material for bearings. The general manufacturing process is shown in Fig. 5.

Table 3 Ratings of ceramic materials as rolling bearing materials Application to rolling bearings Raw materials The raw materials used are silicon nitride (Si3N4) fine powder and a sintering additive. Rating Performance and use Characteristics ・Comparable to bearing steel in load carrying capability and service life ・High speed ・High vacuum ・Corrosion resistant Silicon nitride ◎ ・Suitable for high performance applications ・Heat resistant ・Non-magnetic ・High rigidity The raw material powder is wet blended using a solvent. During this process, the silicon nitride Si3N4 Raw material preparation Preparation powder and sintering additive are mixed evenly in the slurry state. Zirconia ・Useful under a limited load ○ ・Highly corrosion resistant ZrO2 ・Applicable in highly corrosive chemicals A binder is placed in the mixed slurry and a sprayer device is used to produce spherical particles Silicon carbide ・Useful under a limited load Formulation powder ○ ・Highly corrosion resistant ・ Highly heat resistant Drying and granulation with a fixed granularity from the slurry state. SiC ・Applicable in highly corrosive chemicals

Molding The granulated powder is poured into a mold and compacted into the proper shape by compression.

Bearing components are machined until a state close to the final form taking shrinking and layer Molding Machining alteration caused by contraction during sintering into consideration. 4 Composition of ceramic bearings (May be omitted depending items such as shape and accuracy of the compact.)

Degreasing Compact is heated in the degreasing furnace to remove organic matter such as binders. Koyo ceramic bearings are divided into Full Ceramic Bearings (with all Ceramic components, namely, the outer ring, inner ring and rolling elements, made of ceramic) and Hybrid Ceramic Bearings (with only the rolling elements made In the next process of hot isostatic pressing (HIP), a sealed sintered form without openings is Sintering created by applying sufficient gas pressure to the compact. of ceramic). The outer ring and inner ring of the Hybrid Ceramic Bearings are Sintering made from special steel, including high carbon chromium bearing steel. The cage may be made of a metallic material, resin, or composite material, HIP A detailed sintered form is attained in a high- temperature, high-pressure gas environment. depending on the intended operating conditions of the bearing. Full Ceramic Bearing Hybrid Ceramic Bearing

Fig. 4 Composition of ceramic bearings The sintered form attained in the HIP process is ground to the dimensions and surface state of the Grinding process final product. HIP

Inspection The surface is checked after processing to ensure it does not contain cracks or pinholes.

Fig. 5 Ball and roller Bearing Silicon Nitride Manufacturing Process

19 20 Product Details CERAMIC BEARINGS

Ceramic Bearing Product Details

CERAMIC BEARINGS

Silicon nitride, a ceramic material, is more rigid than high carbon chromium Rolling fatigue life of ceramic bearings Static load rating of ceramic bearings bearing steel; therefore, a bearing including silicon nitride components is subject 1 2 to a higher contact stress on the area of contact between bearing raceways and rolling elements. Accordingly, to estimate the service life of ceramic bearings, A typical service life test for Ceramic Bearings and steel bearings was performed The basic static load rating of a steel bearing represents a load that produces a Static load rating of Hybrid Ceramic Bearings whether the rolling bearing theory is applicable or not is critical. under the conditions specified in Fig. 7. localized permanent deformation in the rolling element/raceway contact area, The theory of the static load rating for steel bearings is applicable to Hybrid The test results showed that the service life of Ceramic Bearings was equal to or impeding smooth rotation. Ceramic Bearings because their outer and inner rings are made of steel and longer than that of steel bearings, exceeding the calculated life. However, ceramic materials, which are highly rigid, produce little permanent accordingly any deformation is permanent. Basic dynamic load rating The Ceramic Bearings were found to exhibit flaking (Fig. 6) when their service deformation. Therefore, the theory of the basic static load rating for steel Table 5 shows the results of a test for which a high carbon chromium bearing The ISO standard defines the basic dynamic load rating as the pure radial load life terminated. The same phenomenon was observed on the steel bearings bearings is not applicable to ceramic bearings. steel ball and ceramic ball were pressed against a flat plate of high carbon (for radial bearings), constant in magnitude and direction, under which the basic whose service life terminated. chromium bearing steel and the resulting permanent deformations (indentation rating life of 1 million revolutions can be obtained, when the inner ring rotates Based on these findings, as the dynamic load rating of a Ceramic Bearing, that of Static load rating of Full Ceramic Bearings depths) on the flat plate and balls were measured. while the outer ring is stationary or vice versa. The basic dynamic load rating a steel bearing of the same dimensions can be used. When exposed to continuous excessive loads, ceramic materials may break represents the resistance of a bearing against rolling fatigue. down; however, before breakdown occurs, the materials develop cracking. Fig. 8 compares the load measurements at which ceramic balls developed Table 5 Measurements of permanent deformation produced on flat steel plate and balls Basic static load rating cracking with the basic static load ratings of steel bearings. Fig. 9 shows the The basic static load rating is defined as the static load which corresponds to the measurement system. Load Permanent deformation (average), mm Permanent deformation

calculated contact stress shown below, at the center of the most heavily loaded As these results show, the loads at which cracks develop on the Full Ceramic kN Flat plate (bearing steel) Ball (sum of averages), mm raceway/rolling elements. Bearing are far higher than that of the basic static load rating of steel bearings. 0.65 0.5 ̶ 0.5 This means that the basic load ratings specified in the ISO standard can be used 1.3 1.9 ̶ 1.9 Self-aligning ball bearings： 4 600 MPa as the allowable static loads of the Full Ceramic Bearing. 2.6 5.2 ̶ 5.2 Other ball bearings ： 4 200 MPa Ceramic ball Ceramic inner ring Ceramic ball 3.9 9.3 ̶ 9.3 Roller bearings ： 4 000 MPa Fig. 6 Flaking on ceramic ball and inner ring 0.65 0.4 ̶ 0.4 JTEKT defines the dynamic load rating and static load rating of ceramic bearings 1.3 1.3 0.11 1.41 based on the results of their service life tests, the maximum allowable static load 2.6 4.0 0.41 4.41

7 Steel ball of the ceramic materials, the elastic deformation test results of high carbon Steel bearing Full Ceramic Bearing 3.9 6.8 1.18 7.98 70 chromium bearing steel, and other related data, as shown in Table 4. 6206 NC6206 6 50 Crack These results indicate that ceramic balls do not suffer permanent deformation developing load Table 4 Load ratings of ceramic bearings and that the permanent deformation produced on the flat steel plate by the 30 5 ceramic balls is approximately 1.2 times the sum of the deformation produced Hybrid Ceramic Full Ceramic Bearing Bearing on the flat plate by steel ball and the deformation that the steel ball undergo. 4 Accordingly, the static load rating of Hybrid Ceramic Bearings can be determined Dynamic load rating Comparable to steel Comparable to steel Failure, % C r bearings bearings 10 Load, kN based on the permanent deformation of their bearing steel rings. JTEKT uses the 3 load equal to 85% of the static load rating of steel bearings as the static load Static load rating Comparable to steel 85% that of steel rating of the Hybrid Ceramic Bearings. C 0r bearings bearings 5 2 Note) The steel bearings here refer to bearings consisting of rings and rolling elements both made Basic static load rating for steel bearing of high carbon chromium bearing steel. (load that generates a contact stress of 4 600 MPa) Load 1 2 4 6 8 10 20 1 Calculated life ratio Load cell Load (actual life / calculated life) meter Recorder 0 25 50 75 100 Rolling fatigue test conditions (Ball diameter Dw)2，mm2 Filter and Noise Counter Bearing number Material (outer/inner rings and balls) Dimensions, mm Ball amplifier suppressor Acoustic emission NC6206 Silicon nitride (Si3N4) Fig. 8 Crack developing loads for Full Ceramic Bearings Flat plate 30 × 62 × 16 transducer (bore × outside dia. × width) Filter and 6206 Bearing steel (SUJ2) amplifier

Specification Condition Load 5 800 N Rotational speed 8 000 min−1 Fig. 9 Crack generating load measurement system Lubrication oil AeroShell Turbine Oil 500 Temperature 70 ± 2 ℃

Fig. 7 Rolling fatigue life of Full ceramic bearings and steel bearings

21 22 Product Details CERAMIC BEARINGS

3 Impact strength of ceramic bearings 4 Fitting of ceramic bearings

To evaluate the impact strength of ceramic bearings, ceramic balls were When using ceramic bearings, it should be noted that ceramic materials are Table 6 Typical results of static strength test on ceramic bearing shaft fitting crushed by two methods: by a static load and an impact load. The test results largely different from steel materials in the coefficient of linear expansion. Interference, L10 Ring's fracture stress are shown in Fig. 10. Fig. 11 shows the testing methods. Attention should therefore be paid to fitting stresses and temperature rises. µm MPa This figure shows that the impact strength of the ceramic bearings is almost Static crushing test The following are the results of evaluating the fitting of a Ceramic Bearing on Solid shaft 50 399 equal to the static load strength, which means the bearings possess sufficient a stainless steel shaft. Load Hollow shaft 68 332 impact strength. Table 7 Typical results of dynamic strength test on ceramic bearing shaft fitting Housing Max. allowable interference Max. allowable stress for ring 99 µm MPa Outer ring Jig made of Solid shaft 31 243 bearing steel Ceramic balls Inner ring 80 Hollow shaft 43 204 (9.525 mm in dia.) Shaft 60 Impact crushing load 40

Static crushing load 20

10

Failure, % Fig. 12 Bearing fitting

5

Impact crushing test Maximum stress produced by fitting 2 Table 6 shows the results of a static strength test conducted on a ceramic ring

1 fitted on a stainless steel shaft. Table 7 shows the results of a dynamic Weight 50 kg strength test (running test) conducted on a ceramic ring fitted on a stainless 0 1 2 5 10 20 30 40 100 steel shaft. Fig. 13 Ceramic inner ring damaged by dynamic strength test Crushing load, kN Based on the results of these tests, JTEKT makes it a rule for the maximum Load cell stress produced by interference to be no greater than 150 MPa when a Influence of temperature ceramic inner ring is fitted on a stainless steel shaft. Fig. 10 Comparison of static load and impact load that crush ceramic balls Consult JTEKT for applications requiring tighter fitting. During operation, bearing temperature exceeds the ambient temperature. When a ceramic bearing is operated on a stainless steel shaft or in a stainless steel housing, the interference with the shaft increases due to the difference in Dropping linear expansion coefficient while the interference with the housing decreases. (When the outer ring is loose-fitted, the clearance increases.) To determine the class of fit for a ceramic bearing, the maximum temperature during operation should be assessed carefully. Jig made of bearing steel Ceramic balls (9.525 mm in dia.) ■ The maximum stress generated on the inner ring due to the interference with the shaft can be determined from the following equation: σ : Maximum circumferential stress to interference （MPa） 2 2 D i + d σ = P m・ 2 2 P m : Pressure of contact on fitting surface （MPa） D i －d

d , D i : Inner ring bore diameter and outside diameter （mm）

2 2 2 2 -1 d D i + d d d +d 0 B S ⊿ deff : Effective interference of inner ring （mm） P m =⊿ deff 2 2 + ν + 2 2 －ν E B ( D i －d ) E S ( d －d 0 ) Fig. 11 Ceramic ball crushing test method d 0 : Bore diameter of hollow shaft （mm）

E B , νB : Bearing's modulus of longitudinal elasticity and Poisson's ratio（MPa）

E S , νS : Shaft's modulus of longitudinal elasticity and Poisson's ratio （MPa）

23 24 Performance CERAMIC BEARINGS

Ceramic Bearing Capacities

CERAMIC BEARINGS

1 Corrosion resistance 2 Non-magnetic performance

Table 8 shows the corrosion resistance of ceramic materials. Silicon nitride, There are two types of ceramic corrosion: One is the corrosion of the Bearings may be exposed to magnetic fields in some applications, including

which is used as the standard material of the ceramic bearings, is excellent in alumina-yttria system sintering aid (Al2O3-Y2O3), which is used to bake ceramic equipment associated with super conductivity, semiconductor production corrosion resistance. However, it may develop corrosion in a highly corrosive materials. To avoid this type of corrosion, corrosion resistant silicon nitride 80℃, 35 ％ HCl × 100h 80℃, 35 ％ KOH × 100h facilities and medical examination facililies. If steel bearings are used for such

chemical, a high temperature, or other highly corrosive ambient condition. treated with a spinel sintering aid (MgAl2O4) should be used. Fig. 14 shows the applications, the running torque may fluctuate or the magnetic field may be 0.2 mass reduction and bending strength deterioration of corrosion resistant silicon disturbed . Non-magnetic bearings should be used for such applications. As a Table 8 Corrosion resistance of ceramic materials nitride dipped in an acid or alkaline solution for a given period of time. non-magnetic material for such bearings, beryllium copper has conventionally The other type of corrosion is the corrosion of the silicon nitride itself. For use 0.1 been used. However the use of beryllium copper should be avoided since it ◎：Fully resistant ○：Almost resistant △：Slightly susceptible ×：Susceptible in a highly corrosive solution, bearings made of zirconia (ZrO2) or silicon contains beryllium, a substance of environmental concern.

Ceramic Corrosion Mass reduction, % Silicon nitride materials resistant Zirconia Silicon Carbide carbide (SiC) may be effective. For such applications, JTEKT supplies Hybrid Ceramic Bearings, whose rings Corrosive (standard) silicon nitride 0 ZrO2 SiC solutions Si3N4 Si3N4 To select a ceramic bearing for use in a highly corrosive environment, its Standard Corrosion Standard Corrosion are made of non-magnetic stainless steel and rolling elements are made of a resistant resistant Hydrochloric acid △ ◯ ◯ ◎ corrosion resistance to the specific condition should be carefully examined. ceramic material, or the full ceramic bearings. Nitric acid △ ◯ ◯ ◎ 80℃, 35 ％ HCl × 100h 80℃, 35 ％ KOH × 100h Table 10 Non-magnetic bearings and relative permeability Sulfuric acid △ ◯ ◯ ◎ 40 Phosphoric acid ◯ ◯ ◯ ◎ Relative permeability 30 Fluorine acid △ △ × ◎ Non-magnetic Hybrid Ceramic Bearings 1.01 or lower 20 Sodium hydroxide △ △ ◯ △ Ceramic Bearing 1.001 or lower Potassium hydroxide △ △ △ △ 10 (Ref.) Beryllium copper 1.001 or lower Sodium carbonate △ △ △ △ Bending strength deterioration, % 0 Fig. 16 shows a rolling fatigue strength evaluation result for various △ △ △ △ Standard Corrosion Standard Corrosion Sodium nitrate resistant resistant non-magnetic materials. As can be seen from the figure, non-magnetic stainless Water and saltwater ◎ ◎ ◎ ◎ steel is superior to beryllium copper in rolling fatigue strength.

Note) The corrosive natures of individual solutions differ largely depending on the concentration and temperature. Note that mixing two or more chemicals may increase the corrosivity. Fig. 14 Anticorrosive performance of corrosion resistant silicon nitride

4 Silicon nitride

Service life of corrosion resistant bearings 3 Table 9 lists the bearings suitable for applications requiring corrosion resistance, along with their major applications.

2 Table 9 Typical corrosion resistant Ceramic Bearings Non-magnetic stainless steel Load, kN Bearing Materials Applications 1 Bearing Rings Balls Corrosion Resistant Hybrid Beryllium copper Ceramic Bearing Hybrid Ceramic Bearing In water, alkaline environment and (Bearing rings: SUS630) (Bearing rings: SUS440C) Corrosion Resistant Hybrid Ceramic Bearing reactive gas SUS630 Silicon nitride 100 200 300 400 500 In a slightly acidic environment, alkaline Time, h Ceramic Bearing environment and reactive gas Silicon nitride Silicon nitride Ceramic Bearing 90 In a strongly acidic environment, strongly Test conditions Corrosion Resistant Ceramic Bearing alkaline environment and reactive gas Corrosion resistant silicon nitride Corrosion resistant silicon nitride 50 –1 In a strongly acidic environment, strongly Service life rating Rotational speed 1 200 min High Corrosion Resistant Ceramic Bearing alkaline environment and corrosive gas Silicon carbide Silicon carbide of steel bearings Temperature Room temp.

Failure, % 10 When Ceramic Bearings are operated in a solution, the solution serves as a enough, such as in water, it is important to evaluate in advance the susceptibility Down to 3% lubricant. This means the solution is closely associated with the service life of of the bearings to corrosion and the relationship between the bearing load and 5 Lubricant the bearings. Fig. 15 shows the service life evaluation results for three types of wear in the solution. 1 Ceramic Bearings under water. 10 50 100 500 1 000 5 000 10 000 The Ceramic Bearings terminate their service life due to the flaking on the SUS440C has a longer service life than SUS630; however, the former steel is not Service life, h Test conditions Ceramic balls 9.525 mm bearing ring or ball surfaces. suitable for use in water because it may rust and cause contamination. Bearing No.: 6206 or equivalent Radial load: （ ） In case of the Hybrid Ceramic Bearings, ceramic balls do not develop flaking or Ceramic Bearings may develop wear at an early stage of use depending on the Rotational speed: 1 500 min−1 Ceramic Bearing: 1 470 N Test specimen Corrosion Resistant Hybrid Ceramic Bearing: 196 N wear. Their service life ends due to wear attributed to the minute corrosion of characteristics of the solution, temperature, and load. Please contact JTEKT Hybrid Ceramic Bearing: 196 N Load stainless steel bearing rings. before using Ceramic Bearings in solutions. When bearings are used in a solution whose lubrication performance is not Fig. 15 Comparison in underwater service life of Ceramic Bearings Fig. 16 Comparison of non-magnetic materials in rolling fatigue strength

25 26 Performance CERAMIC BEARINGS

3 Insulation 4 High-speed performance

A cause of bearing failure in motors or generators is electric pitting. Electric Hybrid Ceramic Bearings, whose rolling elements are made of a ceramic material Seizure limit at high speed pitting occurs when a surface in rolling contact is locally molten due to sparks with a density lower than that of bearing steel, are most suitable for high speed Fig. 21 shows the seizure limits of Hybrid Ceramic Bearings and steel bearings. produced over the very thin lubricating oil film on the surface when electricity Continuous sparks of weak current applications. This is because reduced mass of rolling elements suppresses the The limits were measured by gradually reducing lubricating oil feed rate. passes through the bearing in operation. centrifugal force of the rolling elements, as well as slippage attributable to the Compared with general purpose steel bearings, Hybrid Ceramic Bearings Example of electric pitting on inner ring raceway surface Electric pitting appears as a series of pits or a series of ridges on the surface in gyro-moment, when the bearings are in operation. consume smaller amount of lubricating oil under the same speed condition, while rolling contact, which is shown in Fig. 17 and Fig. 18. Thanks to their superior high speed performance, Hybrid Ceramic Bearings are they can run at a higher speed under the same luburicating oil feed rate condition. An estimation of the mechanism that causes electric pitting on a bearing is used in turbochargers and on machine tool spindles. shown in Fig. 19. Power losses at high speed Steel bearing, running Fig. 20 compares power losses between the Hybrid Ceramic Bearings and Steel bearing, seized steel bearings. Hybrid Ceramic Bearing, running When compared to steel bearings, the Hybrid Ceramic Bearings lose smaller Hybrid Ceramic Bearing, seized power during high speed operation. The power loss decreases with increasing rotational speed. 0.5 The Hybrid Ceramic Bearings also have superior antiseizure characteristics, which means that they consume smaller amount of lubrication oil and thereby 0.4 Wave-like wear reduce rolling resistance (power loss).

Fig. 17 Fig. 18 Electric pitting generated on Electric pitting generated on Wave-like wear 0.3 general purpose bearings general purpose bearings 2 marks along entire Steel bearing (pits) (ridges) inner ring raceway seizure limit surface 0.2 To avoid such pitting, a bypass is provided to ensure that no electric current Steel bearings 1.5 Hybrid passes through the bearing. Another method is to use an insulating bearing that Lubrication oil feed rate, L/min. Ceramic Bearing seizure limit can block electric current. 0.1 Since ceramic materials exhibit an excellent insulation performance, Hybrid Ceramic Bearings consisting of ceramic rolling elements can be used as 1 0 insulating bearings. 40 60 80 100 120 Power loss, kW Hybrid Ceramic Bearings prevent electric pitting, also reduce bearing Hybrid Rotational speed, ×103 min−1 temperature rise, and lengthen grease service life. For these reasons, Hybrid Ceramic Bearings Ceramic Bearings assure long term maintenance free operation and high speed 0.5 Fig. 21 Comparison between Hybrid Ceramic Bearings and equipment operation. Electrical potential difference generated steel bearings in seizure limit between inner and outer ring when motor runs 0 20 40 60 80 100 3 −1 Current flows through oil film between Rotational speed, ×10 min raceway rolling surface/balls Hybrid Ceramic Bearings Steel bearings Bearing rings High speed tool steel (M50) Ceramic High speed tool steel Rolling portion surface Material temperature rises - softens (Si3N4) (M50)

Balls Dia. 6.35 mm Number of balls 9 Ball rolling Cage Polyimide resin Rolling surface wear Condition Specification Axial load 200 N Wave-life wear occurs Rotational speed (max.) 100 000 min−1 Lubricating oil AeroShell Turbine Oil 500 Ambient temperature Room temp.

Fig. 19 Estimation of electric pitting (wave-like wear) occurrence mechanism Fig. 20 Comparison in power loss between Hybrid Ceramic Bearings and steel bearings

27 28 Product Introduction CERAMIC BEARINGS 1 Ceramic balls

CERAMIC BEARINGS

www.jtekt.co.jp JTEKT also supplies Ceramic Balls (silicon nitride), which have excellent resistance to wear and seizure, and are usable in corrosive environments and OFFICES ultrahigh vacuums. Other major features of these balls are excellent heat KOYO CANADA INC. JTEKT KOREA CO., LTD. 5324 South Service Road, Burlington, Ontario L7L 5H5, CANADA Seong-do Bldg 13F, 207, Dosan-Dearo, Gangnam-Gu, Seoul, resistance (up to 800°C), high rigidity, lightweight (40% compared to TEL : 1-905-681-1121 KOREA FAX : 1-905-681-1392 TEL : 82-2-549-7922 bearing steel), non-magnetic, and have insulating characteristics. FAX : 82-2-549-7923 JTEKT NORTH AMERICA CORPORATION The Ceramic Balls are useful in many applications such as jigs, tools, -Main Office- JTEKT (CHINA) CO., LTD. 47771 Halyard Drive, Plymouth, MI 48170, U.S.A. Room.25A2, V-CAPITAL Building, 333 Xianxia Road, Changning gauges, solenoid valves, check valves, other valve varieties, high grade TEL : 1-734-454-1500 District, Shanghai 200336, CHINA FAX : 1-734-454-7059 TEL : 86-21-5178-1000 bicycle parts, automotive parts, and machine components. -Cleveland Office- FAX : 86-21-5178-1008 29570 Clemens Road, P.O.Box 45028, Westlake, OH 44145, U.S.A. KOYO AUSTRALIA PTY. LTD. TEL : 1-440-835-1000 Unit 2, 8 Hill Road, Homebush Bay, NSW 2127, AUSTRALIA FAX : 1-440-835-9347 TEL : 61-2-8719-5300 FAX : 61-2-8719-5333 KOYO MEXICANA, S.A. DE C.V. Av. Insurgentes Sur 2376-505, Col. Chimalistac, Del. Álvaro JTEKT EUROPE BEARINGS B.V. Table of Dimensions and Masses Obregón, C.P. 01070, México, D.F. Markerkant 13-01, 1314 AL Almere, THE NETHERLANDS TEL : 52-55-5207-3860 TEL : 31-36-5383333 FAX : 52-55-5207-3873 FAX : 31-36-5347212 -Benelux Branch Office- KOYO LATIN AMERICA, S.A. Energieweg 10a, 2964 LE, Groot-Ammers, THE NETHERLANDS TEL : 31-184-606800 Nominal dimension Nominal outside Precision Mass 2) Nominal dimension Nominal outside Precision Mass 2) Edificio Banco del Pacifico Planta Baja, Calle Aquilino de la Guardia y Calle 52, Panama, REPUBLICA DE PANAMA FAX : 31-184-606857 diameter grade 1) (per piece) diameter grade 1) (per piece) mm inch mm mm inch mm TEL : 507-208-5900 -Sosnowiec Branch Office- FAX : 507-264-2782/507-269-7578 ul3 Maja14, 41-200 Sosnowiec, POLAND TEL : 48-32-720-1444 0.8 0.800 00 0.866 mg 7/16 11.112 75 2.320 8 g KOYO ROLAMENTOS DO BRASIL LTDA. FAX : 48-32-746-7746

1.000 00 1.691 mg 15/32 11.906 25 2.854 5 g Avenida Brigadeiro Faria Lima, 1744 – 1st Floor – CJ. 11 1.0 São Paulo - SP - Brazil CEP 01451-001 KOYO KULLAGER SCANDINAVIA A.B. 5 and 10 1.2 1.200 00 2.922 mg 1/2 12.700 00 3.46 g TEL : 55-11-3372-7500 Johanneslundsvägen 4, 194 61 Upplands Väsby, SWEDEN FAX : 55-11-3887-3039 TEL : 46-8-594-212-10

1/16 1.587 50 6.766 mg 17/32 13.493 75 4.2 g FAX : 46-8-594-212-29 KOYO MIDDLE EAST FZE 2.0 2.000 00 13.530 mg 9/16 14.287 50 4.9 g 6EA 601, Dubai Airport Free Zone, P.O. Box 54816, Dubai, U.A.E. KOYO (U.K.) LIMITED TEL : 97-1-4299-3600 Whitehall Avenue, Kingston, Milton Keynes MK10 0AX, 3/32 2.381 25 22.836 mg 19/32 15.081 25 5.8 g FAX : 97-1-4299-3700 UNITED KINGDOM TEL : 44-1908-289300 7/64 2.778 12 3 and 5 36.262 mg 5/8 15.875 00 6.8 g KOYO BEARINGS INDIA PVT. LTD. FAX : 44-1908-289333 C/o Stylus Commercial Services PVT LTD, Ground Floor, The 1/8 3.175 00 54.129 mg 3/4 19.050 00 11.7 g Beech, E-1, Manyata Embassy Business Park, Outer Ring Road, KOYO DEUTSCHLAND GMBH Bengaluru-560045, INDIA Bargkoppelweg 4, D-22145 Hamburg, GERMANY 3.5 3.500 00 72.511 mg 13/16 20.637 50 40 14.9 g TEL : 91-80-4276-4567 (Reception Desk of Service Office) TEL : 49-40-67-9090-0

5/32 3.968 75 0.105 7 g 7/8 22.225 00 18.6 g FAX : 91-80-4276-4568 FAX : 49-40-67-9203-0

3/16 4.762 50 0.182 7 g 15/16 23.812 50 22.8 g JTEKT (THAILAND) CO., LTD. KOYO FRANCE S.A. 172/1 Moo 12 Tambol Bangwua, Amphur Bangpakong, 6 avenue du Marais, BP20189, 95105 Argenteuil, FRANCE

7/32 5.556 25 0.290 1 g 1 25.400 00 27.7 g Chachoengsao 24180, THAILAND TEL : 33-1-3998-4202 TEL : 66-38-533-310~7 FAX : 33-1-3998-4244/4249 15/64 5.953 12 0.356 8 g 1 1/8 28.575 00 39.5 g FAX : 66-38-532-776 KOYO IBERICA, S.L. 1/4 6.350 00 0.433 0 g 1 3/16 30.162 50 46.4 g PT. JTEKT INDONESIA Avda.de la Industria, 52-2 izda 28820 Coslada Madrid, SPAIN Jl. Surya Madya Plot I-27b, Kawasan Industri Surya Cipta, TEL : 34-91-329-0818 17/64 6.746 88 0.519 4 g 1 1/4 31.750 00 54.1 g Kutanegara, Ciampel, Karawang Jawa Barat, 41363 INDONESIA FAX : 34-91-747-1194 TEL : 62-267-8610-270 9/32 7.143 75 0.616 6 g 1 5/16 33.337 50 60 62.7 g FAX : 62-267-8610-271 KOYO ITALIA S.R.L. Via Stephenson 43/a 20157 Milano, ITALY 5/16 7.937 50 0.845 8 g 1 1/2 38.100 00 93.5 g KOYO SINGAPORE BEARING (PTE.) LTD. TEL : 39-02-2951-0844 5 11/32 8.731 25 1.125 7 g 27, Penjuru Lane, Level 5, Phase 1 Warehouse #05-01. FAX : 39-02-2951-0954 SINGAPORE 609195 -Romanian Representative Office- 3/8 9.525 00 1.461 5 g TEL : 65-6274-2200 24, Lister Street, ap. 1, sector 5, Bucharest, ROMANIA FAX : 65-6862-1623 TEL : 40-21-410-4182 13/32 10.318 75 1.858 2 g FAX : 40-21-410-1178 PHILIPPINE KOYO BEARING CORPORATION 6th Floor, One World Square Building, #10 Upper McKinley Notes 1) For the grades, those specified in JIS B 1501 shall apply. Road, McKinley Town Center Fort Bonifacio, 1634 Taguig City, PHILIPPINES 2) The masses are calculated on the basis of 3.23 g/cm3 in density. TEL : 63-2-856-5046/5047 FAX : 63-2-856-5045

PUBLISHER JTEKT CORPORATION NAGOYA HEAD OFFICE No.7-1, Meieki 4-chome, Nakamura-ku, Nagoya, Aichi 450-8515, JAPAN TEL:81-52-527-1900 FAX:81-52-527-1911 Numbering System 5/32 G5 NCR JTEKT CORPORATION OSAKA HEAD OFFICE No.5-8, Minamisemba 3-chome, Chuo-ku, Osaka 542-8502, JAPAN TEL:81-6-6271-8451 FAX:81-6-6245-3712

Material code: silicon nitride ceramic Sales & Marketing Headquarters No.5-8, Minamisemba 3-chome, Chuo-ku, Osaka 542-8502, JAPAN TEL:81-6-6245-6087 FAX:81-6-6244-9007 Precision grade code Nominal dimension

29 30 FOR EXTREME SPECIAL ENVIRONMENTS CERAMIC BEARINGS

CAT. NO. B1013E Printed in Japan '15.12-1CCH