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JTEKT
Miniature and Extra-Small Ball Bearings

Miniature and Extra-Small Ball Bearings

Product catalog summary

Preface: The catalog introduces JTEKT's miniature and extra-small ball bearings, highlighting their significance in industrial applications that demand high tolerance and low torque. JTEKT employs advanced research and production techniques to improve bearing performance and longevity.

Bearing Technical Section:

Bearing Types and Features: Describes various types of miniature and extra-small ball bearings, including open, shielded, and sealed types, and their specific applications.
Bearing Life and Load Rating: Discusses the calculation of bearing service life, dynamic equivalent load, and static load ratings.
Bearing Tolerances: Details the tolerances applicable to these bearings.
Rotation Speed Limit: Provides guidelines for correcting rotation speed limits and specific limits for sealed bearings.
Bearing Fits and Internal Clearance: Emphasizes the importance of proper fits and internal clearance for optimal bearing performance.
Preload of Bearings: Explains the objectives and methods of preloading bearings.
Bearing Lubrication: Describes lubrication objectives, methods, and grease life for shielded and sealed bearings.
Bearing Torque and Materials: Discusses torque considerations and materials used in bearing construction.
Handling of Bearings: Provides precautions for handling, storage, mounting, and dismounting bearings.
Ceramic Bearings: Highlights the properties, features, and applications of ceramic bearings.

Bearing Dimension Tables: Includes detailed tables for metric series deep groove ball bearings, covering standard, narrow-width, and flanged series.

Supplementary Tables: Provides additional data such as bearing number correspondence, shaft and housing bore tolerances, and conversion factors.

Environmental Considerations: The catalog is printed on 100% waste paper pulp using soy ink, reflecting JTEKT's commitment to environmental protection.

Specifications and Components:
1. Cage Types: Describes two main types of cages used in miniature and extra-small ball bearings: ribbon or crown type cages made of stainless steel, and molded polyamide resin cages.
2. Lubricant Codes: Provides codes for different types of shielding and sealing.
3. Bearing Type Codes: Codes like ML and WML indicate standard and wide types, with specific numbers denoting nominal bearing bore and outside diameters.

Bearing Life and Load Rating:
1. Bearing Life: Bearing life is determined by the number of rotations before damage due to material fatigue occurs.
2. Calculation of Bearing Service Life: Equations are provided to calculate the basic rating life and corrected rating life.
3. Temperature Corrections: High temperatures can alter the material structure of bearings, affecting their hardness and load ratings.
4. Dynamic Equivalent Load: Bearings often experience a combination of radial and axial loads.

Static Load Rating and Safety:
1. Basic Static Load Rating: Refers to the static load that causes a specific contact stress.
2. Static Equivalent Load: A virtual load calculated to produce the same contact stress as actual loading conditions.
3. Safety Coefficient: Used to estimate the degree of safety for a basic static load rating.

Values of Safety Coefficient (fs): For ball bearings, the minimum safety coefficient varies based on operating conditions.

Bearing Tolerances: Tables detail tolerances for inner and outer rings of miniature and extra-small ball bearings.

Rotation Speed Limit: The rotation speed of bearings is limited by temperature increases due to frictional heat.

Bearing Fits: Light interference or slight clearance fits are recommended for miniature and extra-small ball bearings.

Bearing Internal Clearance: Internal clearance refers to the movement of the inner ring relative to the outer ring.

Preload of Bearings: Preloading is used to improve positioning accuracy and minimize vibration.

Bearing Lubrication: Lubrication reduces friction, removes heat, and extends bearing life.

Bearing Torque: Bearing torque is influenced by factors like cage sliding friction and lubricant viscosity.

Bearing Materials: Materials for bearings include high carbon chrome steel and stainless steel for corrosion resistance.

Handling Precautions: Miniature and extra-small ball bearings require careful handling to avoid damage.

Ceramic Bearings: Ceramic bearings are lightweight, heat-resistant, corrosion-resistant, non-magnetic, and non-conductive.

Specifications and Tolerances: Outlines the static equivalent radial load formula and tolerances for dimensions.

Boundary Dimensions and Load Ratings: Details are provided for various bearings, including boundary dimensions, basic load ratings, limiting speeds, and mass.

Operating Conditions: Bearings are designed to operate under specific conditions.

Pull-out Strength of Flange: The pull-out strength values are valid when an axial load is evenly applied to the flange.

Supplementary Tables: Several tables provide additional information, such as bearing number correspondence and shaft tolerances.

Shaft Tolerances: Includes a detailed table of shaft tolerances for various nominal shaft diameters.

Overview: Provides detailed specifications and tolerance guidelines for miniature and extra-small ball bearings.

Specifications: Outlines the deviation classes for housing bore diameters.

Procedures: Provides guidelines on applying these tolerances to bearings.

Standards: References standard tolerance grades and provides a comprehensive table of tolerance values.

Recommendations: Includes recommendations for using specific tolerance grades for different applications.

Conversion Factors: Includes supplementary tables with conversion factors for SI units and other units.

Key Data: Tables provide critical data on permissible deviations and tolerance grades.

SI Units and Conversion Factors: Provides a list of SI units and their conversion factors for various physical quantities.

Steel Hardness Conversion: Provides a conversion table for steel hardness across different scales.

Viscosity Conversion: Includes a table for converting kinematic viscosity to other units.

Global Network: Lists the global offices and manufacturing plants of JTEKT and KOYO.

Catalog excerpts

Miniature and Extra-Small Ball Bearings-1

Miniature and • General Bearings • Extra-Small Ball Bearings Miniature and Extra-Small Ball Bearings TM This catalog has been printed on paper of 100% waste paper pulp using environmentally friendly soy ink. CAT. NO. B2015E Printed in Japan '07.09-1CDS

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Miniature and Extra-Small Ball Bearings-2

Miniature and Extra-Small Ball Bearings CONTENTS Bearing Technical Section 1 1. Bearing Types and Features 8. Bearing Lubrication 1.1 Types and Features ········································ 2 8.1 Objective of Lubrication and Methods··········· 21 1.2 Designation Structure ····································· 4 8.2 Grease Lubrication ······································· 21 1.3 Cages ····························································· 6 8.3 Oil Lubrication ··············································· 21 2. Bearing Life and Load Rating 8.4 Grease Life of Shielded and Sealed...

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Miniature and Extra-Small Ball Bearings-4

EXTRA-SMALL BALL BEARINGS Value & Technology

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Miniature and Extra-Small Ball Bearings-6

EXTRA-SMALL BALL BEARINGS CATALOG Thank you for your valuable support of JTEKT products. Recent industrial applications demand more sophistication in a variety of machines and equipment with the improvement of environment-protection policy. Rotation parts for information processing, audio, and visual equipment that include such features as high tolerance and low torque are highly desired by users. To meet such demands, we at JTEKT exploit state-of-the-art research facilities and leading- edge production methods to improve the performance and life of tolerance miniature and extra- small ball bearings....

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Miniature and Extra-Small Ball Bearings-8

Miniature and Extra-Small Ball Bearings CONTENTS Bearing Technical Section 1 1. Bearing Types and Features 1.1 Types and Features ························································································2 1.2 Designation Structure ·····················································································4 1.3 Cages ·············································································································6 2. Bearing Life and Load Rating 2 3 4 2.1 Bearing Life ·····································································································6...

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