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TECHNICAL REPORT
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TECHNICAL REPORT
Product catalog summary
ISO Dimensional System and Bearing Numbers
- ISO Dimensional System: This system standardizes the dimensions of rolling bearings to ensure global compatibility, covering bore diameter, outside diameter, width, and chamfer dimensions. It includes dimensions from a bore size of 0.6 mm to an outside diameter of 2500 mm, with specific equations for radial and thrust bearings.
- Formulation of Bearing Numbers: Bearing numbers are not standardized by ISO but often follow systems like SKF. Japanese manufacturers use a 4 or 5-digit system combining width and diameter series symbols. Bore diameter symbols are derived from the bore size, with specific rules for dimensions less than 17 mm.
Introduction to Bearing Symbols: The document explains the use of numbers and letters to designate various types and sizes of bearings, such as cylindrical roller bearings using letters like N, NU, NF, NJ.
Bearing Number Formulation: This involves components like bore number, diameter series symbol, width series symbol, type symbol, dimensional series symbol, and bearing series symbol.
Tapered Roller Bearings (Inch System): The ABMA standard specifies bearing numbers for tapered roller bearings in the inch system, requiring both the outer ring (CUP) and inner ring (CONE) to be ordered.
Miniature Ball Bearings: Bearings with outside diameters below 9 mm, used in devices like VCRs and computer peripherals, with special capabilities indicated by descriptive symbols.
Auxiliary Bearing Symbols: These indicate various capabilities and are not fully standardized, varying by manufacturer.
Dynamic Load Rating and Fatigue Life: The basic dynamic load rating is the constant load a bearing can endure for a rating life of one million revolutions, with fatigue life calculated using specific equations.
Specifications and Standards: The document references ISO 281:1990 and JIS B 1518 standards for calculating the basic dynamic load rating, introducing a rating factor (bm) for life extension in improved bearings.
Calculation Procedures: Equations for calculating the dynamic load rating are provided, with variables like diameter, contact angle, and number of rolling elements.
Dynamic Equivalent Load: The document explains calculating the dynamic equivalent load for bearings under combined radial and axial loads.
Load Fluctuation and Speed: Methods for calculating average loads and speeds under fluctuating conditions are outlined.
Combination of Rotating and Stationary Loads: The document describes calculating the combined mean effective load when both rotating and stationary loads are present.
Life Calculation for Multiple Bearings: Guidance is given on calculating the fatigue life of multiple bearings used in a single machine.
Rating Fatigue Life: The document discusses the expected life span of bearings under specific conditions, with a 90% probability of survival.
Calculation Method: The fatigue life of a group of bearings can be calculated using a graphical method involving a chart.
Example: An example is provided for calculating the fatigue life of automotive front wheel bearings.
Load Factor and Fatigue Life: The document explains the importance of considering loads, rotating speed, and other conditions when selecting bearings.
Radial Clearance and Fatigue Life: The effect of radial clearance on bearing fatigue life is discussed.
Misalignment and Fatigue Life: The impact of misalignment on the fatigue life of bearings is analyzed.
Fatigue Life and Reliability: The document emphasizes the importance of reliability in critical applications.
Introduction
This document discusses factors affecting the life and reliability of rolling bearings, focusing on the Weibull distribution, reliability factors, and lubrication impact.
This document discusses factors affecting the life and reliability of rolling bearings, focusing on the Weibull distribution, reliability factors, and lubrication impact.
Weibull Distribution and Reliability Factors
The document explains that bearing life can exceed the theoretical curve of the Weibull distribution, introducing reliability factors (a1) for different reliability percentages.
The document explains that bearing life can exceed the theoretical curve of the Weibull distribution, introducing reliability factors (a1) for different reliability percentages.
Factors Affecting Bearing Durability
Besides rolling fatigue, lubrication, wear, sound, and accuracy are crucial for bearing durability.
Besides rolling fatigue, lubrication, wear, sound, and accuracy are crucial for bearing durability.
Oil Film Parameters and Rolling Fatigue Life
The rolling fatigue life is closely related to lubrication, with the oil film parameter (L) indicating the lubrication state.
The rolling fatigue life is closely related to lubrication, with the oil film parameter (L) indicating the lubrication state.
Elastohydrodynamic Lubrication (EHL)
The document describes calculating the oil film parameter using EHL theory.
The document describes calculating the oil film parameter using EHL theory.
Examples of Oil Film Parameter Calculation
Examples illustrate the calculation of the oil film parameter for different bearings and conditions.
Examples illustrate the calculation of the oil film parameter for different bearings and conditions.
Effects of Oil Shortage and Shearing Heat Generation
Oil shortage and shearing heat generation can reduce the oil film parameter, affecting bearing life.
Oil shortage and shearing heat generation can reduce the oil film parameter, affecting bearing life.
Fatigue Analysis
Fatigue life prediction requires understanding all fatigue breakdown phenomena.
Fatigue life prediction requires understanding all fatigue breakdown phenomena.
Surface and Sub-Surface Fatigues
Sub-surface fatigue is governed by internal shearing stress, while surface fatigue is influenced by lubrication conditions.
Sub-surface fatigue is governed by internal shearing stress, while surface fatigue is influenced by lubrication conditions.
Introduction
This document provides an in-depth analysis of bearing fatigue, focusing on surface and sub-surface fatigue patterns.
This document provides an in-depth analysis of bearing fatigue, focusing on surface and sub-surface fatigue patterns.
Fatigue Analysis of Bearings
Bearings often fail due to surface fatigue before sub-surface fatigue.
Bearings often fail due to surface fatigue before sub-surface fatigue.
Dynamic Load Rating and Fatigue Life
The dynamic load rating is crucial for determining the fatigue life of bearings.
The dynamic load rating is crucial for determining the fatigue life of bearings.
Static Load Ratings and Equivalent Loads
Static load ratings are defined by the contact stress at the center of the contact area.
Static load ratings are defined by the contact stress at the center of the contact area.
Bearing Fitting Practices
Bearing loads are classified by magnitude, time, and direction.
Bearing loads are classified by magnitude, time, and direction.
Conclusion
Understanding fatigue patterns and load ratings is essential for optimizing bearing design and extending service life.
Understanding fatigue patterns and load ratings is essential for optimizing bearing design and extending service life.
Specifications and Fitting Practices
The document discusses fitting practices for bearings, focusing on interference fit.
The document discusses fitting practices for bearings, focusing on interference fit.
Load and Interference
The document outlines the importance of load magnitude in determining interference fit.
The document outlines the importance of load magnitude in determining interference fit.
Temperature Effects
Temperature rise affects interference or clearance due to different coefficients of linear expansion.
Temperature rise affects interference or clearance due to different coefficients of linear expansion.
Fit Calculation and Stress Analysis
The document explains calculating effective interference and the importance of selecting the right fit.
The document explains calculating effective interference and the importance of selecting the right fit.
Mounting and Withdrawal Loads
Mounting and withdrawal loads are calculated using the thick-walled cylinder theory.
Mounting and withdrawal loads are calculated using the thick-walled cylinder theory.
Tolerances
The document concludes with a discussion on tolerances for bore diameter and outside diameter.
The document concludes with a discussion on tolerances for bore diameter and outside diameter.
Diameter Deviation and Bearing Fits
This section provides detailed specifications for diameter deviations in bearings of normal class.
This section provides detailed specifications for diameter deviations in bearings of normal class.
Bearing Fitting Practices
The document discusses fitting practices for four-row tapered roller bearings.
The document discusses fitting practices for four-row tapered roller bearings.
Internal Clearance
Internal clearance is crucial for bearing performance, affecting load distribution, noise, and vibration.
Internal clearance is crucial for bearing performance, affecting load distribution, noise, and vibration.
Calculating Residual Internal Clearance
This section provides a step-by-step procedure for calculating residual internal clearance after mounting.
This section provides a step-by-step procedure for calculating residual internal clearance after mounting.
Effect of Interference Fit on Bearing Raceways
The document explains how interference fits affect radial clearance.
The document explains how interference fits affect radial clearance.
Specifications and Procedures:
The document discusses the fit of bearing rings on shafts and housings.
The document discusses the fit of bearing rings on shafts and housings.
Effect of Temperature Differences:
The document addresses the reduction in radial internal clearance caused by temperature differences.
The document addresses the reduction in radial internal clearance caused by temperature differences.
Radial and Axial Internal Clearances:
For single-row deep groove ball bearings, the document defines radial and axial internal clearances.
For single-row deep groove ball bearings, the document defines radial and axial internal clearances.
Contact Angles and Angular Clearances:
The document explains the relationship between radial clearance and contact angle.
The document explains the relationship between radial clearance and contact angle.
Data and Examples:
The document includes tables and figures illustrating relationships between various parameters.
The document includes tables and figures illustrating relationships between various parameters.
Specifications and Definitions:
The document discusses the geometry and relationships in ball bearings.
The document discusses the geometry and relationships in ball bearings.
Mathematical Relationships:
Several equations describe relationships between radial and axial clearances.
Several equations describe relationships between radial and axial clearances.
Clearance and Contact Angles:
The document explains how the contact angle varies for different bearing series.
The document explains how the contact angle varies for different bearing series.
Angular Clearances:
Angular clearance in double-row angular contact ball bearings is defined similarly to single-row bearings.
Angular clearance in double-row angular contact ball bearings is defined similarly to single-row bearings.
Measuring Internal Clearance:
Methods for measuring internal clearance in combined tapered roller bearings are detailed.
Methods for measuring internal clearance in combined tapered roller bearings are detailed.
Adjustment Methods:
The document outlines methods for adjusting internal clearance when mounting tapered roller bearings.
The document outlines methods for adjusting internal clearance when mounting tapered roller bearings.
Load Distribution:
The section on bearing internal load distribution examines the effects of radial and axial loads.
The section on bearing internal load distribution examines the effects of radial and axial loads.
Figures and Tables:
The document references several figures and tables illustrating relationships between clearances and load distributions.
The document references several figures and tables illustrating relationships between clearances and load distributions.
Specifications and Equations:
The document provides detailed equations and specifications for analyzing the behavior of rolling elements.
The document provides detailed equations and specifications for analyzing the behavior of rolling elements.
Radial Clearance and Load Factor:
Radial clearance affects the load factor, denoted as ε.
Radial clearance affects the load factor, denoted as ε.
Contact Surface Pressure and Ellipse:
The contact between a rolling element and raceway is analyzed using Hertz theory.
The contact between a rolling element and raceway is analyzed using Hertz theory.
Roller Bearings Under Radial Load:
For roller bearings, the document provides equations to calculate contact surface pressure and contact area width.
For roller bearings, the document provides equations to calculate contact surface pressure and contact area width.
Examples and Tables:
Examples demonstrate the application of the equations, including calculations for specific bearing models.
Examples demonstrate the application of the equations, including calculations for specific bearing models.
Specifications and Calculations:
The document provides detailed equations and methodologies for calculating starting and running torques.
The document provides detailed equations and methodologies for calculating starting and running torques.
Empirical Equations:
For high-speed ball bearings, the running torque is expressed as M = Ml + Mv.
For high-speed ball bearings, the running torque is expressed as M = Ml + Mv.
Running Torque of Tapered Roller Bearings:
The running torque is analyzed based on rolling resistance and sliding friction.
The running torque is analyzed based on rolling resistance and sliding friction.
Contact Angle and Axial Load:
The document discusses the change in contact angle due to axial load.
The document discusses the change in contact angle due to axial load.
Figures and Tables:
Figures and tables illustrate relationships between calculated and actual values.
Figures and tables illustrate relationships between calculated and actual values.
Conclusion:
The document provides comprehensive methodologies for calculating starting and running torques.
The document provides comprehensive methodologies for calculating starting and running torques.
Specifications and Load Calculations:
The document provides empirical equations for calculating the allowable axial load.
The document provides empirical equations for calculating the allowable axial load.
Lubrication Guidelines:
For high-speed operations, forced lubrication is recommended.
For high-speed operations, forced lubrication is recommended.
Grease Lubrication for Spindle Bearings:
Spindle bearings should be filled with a standard amount of grease.
Spindle bearings should be filled with a standard amount of grease.
Free Space and Grease Filling for Bearings:
The document discusses the importance of selecting appropriate grease and filling amounts.
The document discusses the importance of selecting appropriate grease and filling amounts.
Key Tables and Data:
The document includes tables with coefficients of dynamic friction and grease filling recommendations.
The document includes tables with coefficients of dynamic friction and grease filling recommendations.
Overview: This document provides detailed technical information on various types of bearings, their lubrication requirements, and specific greases.
1. Bearing Types and Free Space:
- Cylindrical Roller Bearings: Lists different series and their free space ratios.
- Tapered Roller Bearings: Emphasizes the importance of selecting appropriate grease.
- Spherical Roller Bearings: Known for self-aligning ability and capacity to handle large loads.
2. Lubrication and Grease Types:
- NSK's Dedicated Greases: Details specific greases like NS7, NSC, ENS, ENR, EA3, EA6, and WPH.
- NS7 and NSC Greases: Developed for induction motor bearings.
- ENS and ENR Greases: Suitable for high-temperature and high-speed ball bearings.
- EA3 and EA6 Greases: Designed for commutator motor shafts.
- WPH Grease: Specifically for water pump bearings.
3. Key Recommendations:
- Proper selection and application of grease are crucial for maintaining bearing performance.
- Attention to grease filling amounts and conditions is necessary to prevent issues.
- Specific greases are recommended based on the operating environment.
Introduction
The document discusses the characteristics and applications of various greases and bearing materials.
The document discusses the characteristics and applications of various greases and bearing materials.
WPH Grease Features
WPH grease is designed for water pump bearings, offering high reliability in severe environments.
WPH grease is designed for water pump bearings, offering high reliability in severe environments.
MA7 and MA8 Greases
These greases are optimal for automotive electric accessory bearings.
These greases are optimal for automotive electric accessory bearings.
Bearing Materials
The document compares national standards for rolling bearing steel.
The document compares national standards for rolling bearing steel.
Long Life Bearing Steel (NSK Z Steel)
NSK Z steel is developed to enhance rolling fatigue life.
NSK Z steel is developed to enhance rolling fatigue life.
High Temperature Bearing Materials
Materials like high-speed steel and SUS 440C are used for high-temperature applications.
Materials like high-speed steel and SUS 440C are used for high-temperature applications.
Dimensional Stability of Bearing Steel
Aging deformation can lead to inner ring creep.
Aging deformation can lead to inner ring creep.
Conclusion
The document underscores the importance of selecting appropriate greases and materials for bearings.
The document underscores the importance of selecting appropriate greases and materials for bearings.
Characteristics of Bearing and Shaft/Housing Materials
Rolling bearings must withstand high loads, high speeds, and prolonged operation.
Rolling bearings must withstand high loads, high speeds, and prolonged operation.
Engineering Ceramics as Bearing Material
Ceramics offer superior corrosion, heat, and wear resistance.
Ceramics offer superior corrosion, heat, and wear resistance.
Physical Properties of Representative Polymers Used as Bearing Material
Polymers are used for bearing cages due to their lightweight and corrosion resistance.
Polymers are used for bearing cages due to their lightweight and corrosion resistance.
Characteristics of Nylon Material for Cages
Plastic cages, particularly those made from nylon, are increasingly replacing metal cages.
Plastic cages, particularly those made from nylon, are increasingly replacing metal cages.
Material Deterioration in Oils: The document discusses how material deterioration in oils varies based on the type of oil.
Applications of Fiber Reinforced Nylon Cages: Table 1 lists applications for fiber reinforced nylon cages.
Environmental Resistance of Nylon 66 Resin: Table 2 provides data on the time it takes for physical properties of nylon 66 to drop to 50%.
Heat-Resistant Resin Materials for Cages: Polyamide resin is noted for its performance under medium conditions.
Features and Operating Temperature Range of Ball Bearing Seal Material: The document describes different rubber materials used for seals.
Load Calculation of Gears: The document provides detailed calculations for loads on various gears.
Load Calculation of Gears
This section discusses the calculation of forces acting on hypoid gears.
This section discusses the calculation of forces acting on hypoid gears.
Calculation of Load on Worm Gear
Worm gears have their load calculated based on gear ratio and efficiency.
Worm gears have their load calculated based on gear ratio and efficiency.
JIS Standards for Rolling Bearings
Rolling bearings are standardized internationally, with Japan following JIS standards.
Rolling bearings are standardized internationally, with Japan following JIS standards.
Permanent Deformation in Bearings
This section explains the permanent deformation occurring at contact points in bearings.
This section explains the permanent deformation occurring at contact points in bearings.
Specifications and Calculations:
The document discusses the calculation of bearing mass using the apparent specific gravity 'k'.
The document discusses the calculation of bearing mass using the apparent specific gravity 'k'.
Projection of Cage in Tapered Roller Bearings:
The cage projects perpendicularly from the outer ring.
The cage projects perpendicularly from the outer ring.
Natural Frequency of Bearing Rings:
Natural frequencies involve radial and axial vibrations.
Natural frequencies involve radial and axial vibrations.
Vibration and Noise:
Vibration and noise in bearings are categorized into inherent design issues and those caused by external factors.
Vibration and noise in bearings are categorized into inherent design issues and those caused by external factors.
Application of FEM in Bearing Design:
Finite Element Methods (FEM) are used to analyze dynamic and thermal problems in bearing systems.
Finite Element Methods (FEM) are used to analyze dynamic and thermal problems in bearing systems.
Conclusion:
The document provides detailed technical insights into bearing specifications and design considerations.
The document provides detailed technical insights into bearing specifications and design considerations.
Specifications and Procedures:
The document discusses the load distribution in rolling elements of bearings.
The document discusses the load distribution in rolling elements of bearings.
NSK Special Bearings:
Ultra-precision Ball Bearings for Gyroscopes: These bearings are critical for gyroscopes used in airplanes and ships.
Ultra-precision Ball Bearings for Gyroscopes: These bearings are critical for gyroscopes used in airplanes and ships.
Bearings for Vacuum Use: Ball bearings for X-ray tubes operate under high vacuum, high temperature, and high speed.
High Vacuum Ball Bearings: These bearings are coated with solid lubricants for high-vacuum environments.
Light-contact-sealed Ball Bearings: Developed to meet the requirements of low torque and high sealing effectiveness.
Tables and Figures:
The document includes several tables and figures illustrating the specifications and performance characteristics of various bearings.
The document includes several tables and figures illustrating the specifications and performance characteristics of various bearings.
Specifications and Design Features
1. Sealed Bearings: Nitrile rubber seals are color-coded for different contact types.
1. Sealed Bearings: Nitrile rubber seals are color-coded for different contact types.
2. Bearings with Integral Shaft: Designed for high-performance AV and OA equipment.
3. Electromagnetic Clutch Bearings: Used in car air-conditioners.
4. Sealed Clean Bearings for Transmissions: These bearings prevent foreign matter entry.
5. Double-Row Cylindrical Roller Bearings (NN30 T Series): Used in machine tool spindles.
6. Single-Row Cylindrical Roller Bearings (N10B T Series): Designed for rear spindle support.
Performance and Testing
1. Evaluation Tests: Figures and tables illustrate the design and test results of various bearings.
1. Evaluation Tests: Figures and tables illustrate the design and test results of various bearings.
2. Durability and Speed: Bearings are tested for durability at high speeds and temperatures.
Applications and Recommendations
1. Application Conditions: Tables provide detailed specifications for different bearing types.
1. Application Conditions: Tables provide detailed specifications for different bearing types.
2. Grease and Seals: Dedicated greases and seals are developed for high-temperature and high-speed conditions.
Conclusion
NSK's range of special bearings is designed to meet the demanding requirements of modern machinery.
NSK's range of special bearings is designed to meet the demanding requirements of modern machinery.
NSK Special Bearings Overview
1. Sealed Clean Bearings for Rolling Mill Roll Neck
These bearings are designed to withstand harsh environments.
These bearings are designed to withstand harsh environments.
2. Bearings for Chain Conveyors
Used in steelmaking plants, these bearings are designed for low-speed, heavy-load conditions.
Used in steelmaking plants, these bearings are designed for low-speed, heavy-load conditions.
3. RCC Bearings for Railway Rolling Stock
These bearings are designed for high-speed, maintenance-free operation.
These bearings are designed for high-speed, maintenance-free operation.
Technical Specifications
Tables and figures provide detailed dimensions and load ratings for various bearing types.
Tables and figures provide detailed dimensions and load ratings for various bearing types.
Contact Information
The document provides contact details for NSK sales offices across Europe, the Middle East, and Africa.
The document provides contact details for NSK sales offices across Europe, the Middle East, and Africa.
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Catalog excerpts
TECHNICAL REPORT
Open the catalog to page 1
1. ISO Dimensional system and bearing numbers 1.1 1.2 1.3 1.4 1.5 ISO Dimensional system …………………………………………………………… 6 Formulation of bearing numbers…………………………………………………… 8 Bearing numbers for tapered roller bearings (inch system) ………………… 10 Bearing numbers for miniature ball bearings ………………………………… 12 Auxiliary bearing symbols ……………………………………………………… 14 2. Dynamic load rating, fatigue life, and static load rating Dynamic load rating ……………………………………………………………… Dynamic equivalent load ………………………………………………………… Dynamic equivalent load of triplex angular contact ball bearings …………… Average of fluctuating load...
Open the catalog to page 2
Interference and clearance for fitting (shafts and inner rings) ……………… Interference and clearance for fitting (housing holes and outer rings)……… Interference dispersion (shafts and inner rings) ……………………………… Interference dispersion (housing bores and outer rings) …………………… Fits of four-row tapered roller bearings (metric) for roll necks ……………… Internal clearance ………………………………………………………………… Calculating residual internal clearance after mounting ……………………… Effect of interference fit on bearing raceways (fit of inner ring) …………… Effect of interference fit on bearing raceways (fit of outer ring) ……………...
Open the catalog to page 3
Position preload and constant-pressure preload ……………………………… Load and displacement of position-preloaded bearings……………………… Average preload for duplex angular contact ball bearings …………………… Axial displacement of deep groove ball bearings …………………………… Axial displacement of tapered roller bearings ………………………………… Preload and starting torque for angular contact ball bearings ……………… Preload and starting torque for tapered roller bearings ……………………… Empirical equations of running torque of high-speed ball bearings ………… Empirical equations for running torque of tapered roller bearings ………… 8. Bearing type...
Open the catalog to page 4
Pages 10.8 Characteristics of nylon material for cages …………………………………… 220 10.9 Heat-resistant resin materials for cages ……………………………………… 222 10.10 Features and operating temperature range of ball bearing seal material … 224 Calculation Calculation Calculation Calculation Calculation loads on spur, helical, and double-helical gears …………… load acting on straight bevel gears …………………………… load on spiral bevel gears ……………………………………… load acting on hypoid gears …………………………………… load on worm gear ……………………………………………… 12. General miscellaneous information JIS concerning rolling bearings …………………………………………………...
Open the catalog to page 5
1. ISO Dimensional system and bearing numbers 1.1 ISO Dimensional system The boundary dimensions of rolling bearings, namely, bore diameter, outside diameter, width, and chamfer dimensions have been standardized so that common dimensions can be adopted on a worldwide scale. In Japan, JIS (Japan Industrial Standard) adheres to the boundary dimensions established by ISO. ISO is a French acronym which is translated into English as the International Organization for Standardization. The ISO dimensional system specifies the following dimensions for rolling bearings: bore diameter, d, outside diameter,...
Open the catalog to page 6
Fig. 1 Cross-sectional profiles of radial bearings by dimensional series Table 1 fD and fB values of radial bearings Diameter series Width series Table 2 fD and fT values for thrust bearings Diameter series Height series
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NH and NS Series1 Page
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K1-L1 Page
DH/DS Series1 Page
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