GB/T 2363-2025 Accuracy of fine-pitch involute cylindrical gears English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing thorugh draft translation, self-check, revision and varification) will be delivered upon being ordered.
ICS 21.200 CCS J 17
NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA
GB/T 2363-2025
Replacing GB/T 2363-1990
Precision of Involute Cylindrical Spur Gears with Small Modules
Published on 2025-08-29 Implemented on 2026-03-01
Issued by State Administration for Market Regulation
Standardization Administration of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms, Definitions and Symbols
4 Deviations and Tolerances
4.1 Deviations
4.2 Tolerances
5 Tolerance Calculations
5.1 Calculation Formulas
5.2 Application of Formulas
Appendix A (Informative) Measurement of Radial Composite Deviations
Appendix B (Informative) Image Inspection Method for Small Module Gear Profiles
References
IMPORTANT NOTE: Familiarity with GB/T 10095.1-2022, GB/T 10095.2-2023, GB/Z 18620.1, GB/Z 18620.2 and GB/Z 18620.3 is essential for proper application of this document.
1 Scope
This document specifies grading methods and tolerance values for single small module involute cylindrical gear tooth surface accuracy within the following parameters:
0.1 mm ≤ mn < 0.5 mm;
5 ≤ z ≤ 200;
0.5 mm ≤ d ≤ 100 mm;
0.2 mm ≤ b ≤ 10 mm;
β ≤ 45°.
Where:
mn - Normal module;
z - Number of teeth;
d - Pitch circle diameter;
b - Face width (axial);
β - Helix angle.
Note 1: Tolerance values for accuracy are also called allowable deviation values.
Note 2: The accuracy grade obtained according to this document does not directly correlate with the actual performance of the gear.
This document applies to evaluation of manufacturing quality for small module gears made of metal and powder metallurgy materials.
2 Normative References
The following documents' contents are indispensable clauses through normative references in this document. For dated references, only the edition corresponding to the date applies; for undated references, the latest edition (including all amendments) applies.
GB/T 2821 Designation of Gear Geometry Elements
GB/T 3374.1 Gears - Terminology and Definitions - Part 1: Geometrical Definitions
GB/T 10095.1-2022 Cylindrical Gears - ISO System of Accuracy for Gear Tooth Flanks - Part 1: Definitions and Allowable Deviations
GB/T 10095.2-2023 Cylindrical Gears - ISO System of Accuracy for Gear Tooth Flanks - Part 2: Definitions and Allowable Deviations for Radial Composite Deviations
GB/Z 18620.2-2008 Cylindrical Gears - Inspection Specifications - Part 2: Inspection of Radial Composite Deviations, Radial Runout, Tooth Thickness and Backlash
3 Terms, Definitions and Symbols
The terms, definitions and symbols defined in GB/T 2821, GB/T 3374.1, GB/T 10095.1-2022 and GB/T 10095.2-2023 apply to this document.
4 Deviations and Tolerances
4.1 Deviations
4.1.1 General Principles
4.1.1.1 Individual Deviations
The definitions of individual deviations (see Table 1) in this document are consistent with GB/T 10095.1-2022.
This document provides graded tolerances for individual deviations of tooth surface accuracy and specifies measurement requirements for unassembled gears.
Certain design aspects for measurement or unspecified manufacturing processes should be documented in the contract.
When specifying tolerance grades for individual deviations of tooth surface accuracy according to this document, the labeling should follow Sections 4.2.2.1 and 4.2.2.2. Note that the same tolerance grade may correspond to different values compared to previous versions.
4.1.1.2 Composite Deviations
The definitions of composite deviations (see Table 1) in this document are consistent with GB/T 10095.1-2022 and GB/T 10095.2-2023.
This document does not provide tolerances for radial composite deviations and tangential composite deviations. However, measurement curves of these two deviations can be used for process control, or to analyze and predict product performance. The measurement method for radial composite deviations is provided in Appendix A.
4.1.2 Required Deviations and Tooth Thickness
The definitions of deviations and tooth thickness are shown in Table 1.
Table 1 Definitions of Deviations and Tooth Thickness
Symbol Detection Item Definition
Gears complying with tolerance grade requirements shall meet all individual deviation requirements specified for the designated tooth surface accuracy grade in Tables 2 and 3.
Table 2 Tolerance Grades and Measurement Items
Tooth Surface Tolerance Grade Minimum Acceptable Parameters
Default Parameter Table Alternative Parameter Table
Table 3 lists the minimum parameters required to comply with this document. When agreed upon by both parties, the alternative parameter table may replace the default parameter table based on available measurement equipment, but the results are for the exclusive use of both parties.
Typically, both sides of the gear teeth should use the same tolerance. In certain cases, the loaded tooth surface may be specified with higher accuracy grades than the unloaded or lightly loaded tooth surface. In such cases, it should be noted on the gear drawing and specify the loaded tooth surface.
Table 3 Typical Measurement Methods and Minimum Number of Teeth to Measure
Inspection Item Typical Measurement Method Minimum Number of Teeth to Measure
4.1.3 Basic Requirements for Individual Deviation Measurements
Except that the filter cutoff wavelength (λα) should not be less than 0.2mn, other requirements shall comply with Section 4.4 of GB/T 10095.1-2022.
4.2 Tolerances
4.2.1 Tooth Surface Tolerances
The tooth surface tolerances specified in engineering drawings or gear calculations shall comply with Section 4.5 of GB/T 10095.1-2022, and shall explicitly reference this document (e.g., accuracy evaluation basis is GB/T 2363-2025).
4.2.2 Acceptance and Evaluation
4.2.2.1 The notation or specification of tooth surface tolerance grades shall follow the format:
GB/T 2363-2025, Grade A
Where: A is the tooth surface accuracy grade number.
4.2.2.2 Different tooth surfaces of the same gear, or different deviation items of the same tooth surface may use different accuracy grades. In such cases, they should be specified separately.
4.2.2.3 Different tooth surface tolerance grades, tolerances, evaluation standards, tooth surface tolerance grade assessments, and additional characteristics shall comply with Sections 4.6.2 to 4.6.6 of GB/T 10095.1-2022.
4.2.2.4 This document does not provide the tooth surface accuracy grades and tolerance values corresponding to the measurement results of tangential composite deviations and radial composite deviations.
Standard
GB/T 2363-2025 Accuracy of fine-pitch involute cylindrical gears (English Version)
GB/T 2363-2025 Accuracy of fine-pitch involute cylindrical gears English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing thorugh draft translation, self-check, revision and varification) will be delivered upon being ordered.
ICS 21.200 CCS J 17
NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA
GB/T 2363-2025
Replacing GB/T 2363-1990
Precision of Involute Cylindrical Spur Gears with Small Modules
Published on 2025-08-29 Implemented on 2026-03-01
Issued by State Administration for Market Regulation
Standardization Administration of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms, Definitions and Symbols
4 Deviations and Tolerances
4.1 Deviations
4.2 Tolerances
5 Tolerance Calculations
5.1 Calculation Formulas
5.2 Application of Formulas
Appendix A (Informative) Measurement of Radial Composite Deviations
Appendix B (Informative) Image Inspection Method for Small Module Gear Profiles
References
IMPORTANT NOTE: Familiarity with GB/T 10095.1-2022, GB/T 10095.2-2023, GB/Z 18620.1, GB/Z 18620.2 and GB/Z 18620.3 is essential for proper application of this document.
1 Scope
This document specifies grading methods and tolerance values for single small module involute cylindrical gear tooth surface accuracy within the following parameters:
0.1 mm ≤ mn < 0.5 mm;
5 ≤ z ≤ 200;
0.5 mm ≤ d ≤ 100 mm;
0.2 mm ≤ b ≤ 10 mm;
β ≤ 45°.
Where:
mn - Normal module;
z - Number of teeth;
d - Pitch circle diameter;
b - Face width (axial);
β - Helix angle.
Note 1: Tolerance values for accuracy are also called allowable deviation values.
Note 2: The accuracy grade obtained according to this document does not directly correlate with the actual performance of the gear.
This document applies to evaluation of manufacturing quality for small module gears made of metal and powder metallurgy materials.
2 Normative References
The following documents' contents are indispensable clauses through normative references in this document. For dated references, only the edition corresponding to the date applies; for undated references, the latest edition (including all amendments) applies.
GB/T 2821 Designation of Gear Geometry Elements
GB/T 3374.1 Gears - Terminology and Definitions - Part 1: Geometrical Definitions
GB/T 10095.1-2022 Cylindrical Gears - ISO System of Accuracy for Gear Tooth Flanks - Part 1: Definitions and Allowable Deviations
GB/T 10095.2-2023 Cylindrical Gears - ISO System of Accuracy for Gear Tooth Flanks - Part 2: Definitions and Allowable Deviations for Radial Composite Deviations
GB/Z 18620.2-2008 Cylindrical Gears - Inspection Specifications - Part 2: Inspection of Radial Composite Deviations, Radial Runout, Tooth Thickness and Backlash
3 Terms, Definitions and Symbols
The terms, definitions and symbols defined in GB/T 2821, GB/T 3374.1, GB/T 10095.1-2022 and GB/T 10095.2-2023 apply to this document.
4 Deviations and Tolerances
4.1 Deviations
4.1.1 General Principles
4.1.1.1 Individual Deviations
The definitions of individual deviations (see Table 1) in this document are consistent with GB/T 10095.1-2022.
This document provides graded tolerances for individual deviations of tooth surface accuracy and specifies measurement requirements for unassembled gears.
Certain design aspects for measurement or unspecified manufacturing processes should be documented in the contract.
When specifying tolerance grades for individual deviations of tooth surface accuracy according to this document, the labeling should follow Sections 4.2.2.1 and 4.2.2.2. Note that the same tolerance grade may correspond to different values compared to previous versions.
4.1.1.2 Composite Deviations
The definitions of composite deviations (see Table 1) in this document are consistent with GB/T 10095.1-2022 and GB/T 10095.2-2023.
This document does not provide tolerances for radial composite deviations and tangential composite deviations. However, measurement curves of these two deviations can be used for process control, or to analyze and predict product performance. The measurement method for radial composite deviations is provided in Appendix A.
4.1.2 Required Deviations and Tooth Thickness
The definitions of deviations and tooth thickness are shown in Table 1.
Table 1 Definitions of Deviations and Tooth Thickness
Symbol Detection Item Definition
Gears complying with tolerance grade requirements shall meet all individual deviation requirements specified for the designated tooth surface accuracy grade in Tables 2 and 3.
Table 2 Tolerance Grades and Measurement Items
Tooth Surface Tolerance Grade Minimum Acceptable Parameters
Default Parameter Table Alternative Parameter Table
Table 3 lists the minimum parameters required to comply with this document. When agreed upon by both parties, the alternative parameter table may replace the default parameter table based on available measurement equipment, but the results are for the exclusive use of both parties.
Typically, both sides of the gear teeth should use the same tolerance. In certain cases, the loaded tooth surface may be specified with higher accuracy grades than the unloaded or lightly loaded tooth surface. In such cases, it should be noted on the gear drawing and specify the loaded tooth surface.
Table 3 Typical Measurement Methods and Minimum Number of Teeth to Measure
Inspection Item Typical Measurement Method Minimum Number of Teeth to Measure
4.1.3 Basic Requirements for Individual Deviation Measurements
Except that the filter cutoff wavelength (λα) should not be less than 0.2mn, other requirements shall comply with Section 4.4 of GB/T 10095.1-2022.
4.2 Tolerances
4.2.1 Tooth Surface Tolerances
The tooth surface tolerances specified in engineering drawings or gear calculations shall comply with Section 4.5 of GB/T 10095.1-2022, and shall explicitly reference this document (e.g., accuracy evaluation basis is GB/T 2363-2025).
4.2.2 Acceptance and Evaluation
4.2.2.1 The notation or specification of tooth surface tolerance grades shall follow the format:
GB/T 2363-2025, Grade A
Where: A is the tooth surface accuracy grade number.
4.2.2.2 Different tooth surfaces of the same gear, or different deviation items of the same tooth surface may use different accuracy grades. In such cases, they should be specified separately.
4.2.2.3 Different tooth surface tolerance grades, tolerances, evaluation standards, tooth surface tolerance grade assessments, and additional characteristics shall comply with Sections 4.6.2 to 4.6.6 of GB/T 10095.1-2022.
4.2.2.4 This document does not provide the tooth surface accuracy grades and tolerance values corresponding to the measurement results of tangential composite deviations and radial composite deviations.
