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This standard is drafted in accordance with the rules given in the GB/T 1.1-2009.
This standard replaces GB/T 4249-2009 Geometrical Product Specifications (GPS) — Tolerancing Principle. The following the following technical deviations have been made with respect to the GB/T 4249-2009 (the previous edition):
— deletion and addition of some terms and definitions (see Clause 3; Clause 3 of Edition 2009);
— move of the "independency principle" to the clause "Fundamental Principles" (see 5.5; Clause 4 of Edition 2009);
— deletion of the clause “Tolerances” (Clause 5 of Edition 2009);
— deletion of the relevant requirements (Clause 6 of Edition 2009);
— deletion of the designation of tolerance principle (Clause 7 of Edition 2009);
— addition of the fundamental assumptions for the reading of specifications on drawings (see Clause 4);
— addition of the fundamental principles (see Clause 5);
— addition of the rules for indication of default specification operators (see Clause 6);
— addition of the rules for indication of special specification operators (see Clause 7);
— addition of the rules for statements in parentheses (see Clause 8);
This standard has been redrafted and modified adoption of International Standard ISO 8015:2011 Geometrical Product Specifications (GPS) — Fundamentals — Concepts, Principles and Rules.
There are technical deviations between this standard and the International Standard ISO 8015:2011, which are marked with perpendicular single line (|) in the outside page margin of the provisions concerned. The technical deviations, together with their justifications, are given beloe:
— the adjustments of technical difference are made for the normative references in this standard so as to adapt to the technical conditions in China. The adjustment is mainly reflected in Clause 2 "Normative references" with the specific adjustments as follows:
● ISO 17450-1 is replaced by GB/Z 24637.1 which is identical with the international standard;
● ISO 17450-2:2009 is replaced by GB/Z 24637.2 which is identical with the international standard;
— the normative reference ISO 17450-2 in ISO 8015:2011 is undated reference, while the reference to 3.5.2 of ISO 17450-2 in 7.1 is an error in the ISO standard and 3.5.2 was deleted during conversion.
For the purposes of this standard, the following editorial changes have also been made:
— in Annex A (Informative), the matrix model of ISO 14638:1995 used in the original standard is changed to the new matrix model of ISO 14638:2015.
This standard was proposed by and is under the jurisdiction of National Technical Committee 240 on Geometrical Product Specifications of Standardization Administration of China (SAC/TC 240).
The previous editions of this standard are as follows:
— GB/T 4249-1984, GB/T 4249-1996, GB/T 4249-2009;
…..
Geometrical Product Specifications (GPS) — Fundamentals — Concepts, Principles and Rules
1 Scope
This standard specifies fundamental concepts, principles and rules valid for the creation, interpretation and application of all other standards, technical specifications and technical reports concerning dimensional and geometrical product specifications (GPS) and verification.
This standard applies to the interpretation of GPS indications on all types of drawings.
For the purposes of this standard, the term “drawing” is to be interpreted in the broadest possible sense, encompassing the total package of documentation specifying the workpiece.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/Z 24637.1 Geometrical Product Specifications (GPS) — General Concepts — Part 1: Model for Geometrical Specification and Verification (ISO/TS 17450-1: 2005, IDT)
GB/Z 24637.2 Geometrical Product Specifications (GPS) — General Concepts — Part 2: Basic Tenets, Specifications, Operators and Uncertainties (GB/Z 24637.2-2009, ISO/TS 17450-2:2002, IDT)
ISO/IEC Guide 98-3:2008 Uncertainty of Measurement — Guide to the Expression of Uncertainty in Measurement (GUM:1995)
ISO/IEC Guide 99:2007 International Vocabulary of Metrology — Basic and General Concepts and Associated Terms (VIM)
3 Terms and Definitions
For the purpose of this standard, the term and definitions given in GB/Z 24637.1, GB/Z 24637.2, ISO/IEC Guide 98-3:2008, ISO/IEC Guide 99:2007 and the following apply.
3.1
ISO GPS system
GPS system
geometrical product specification and verification system developed in ISO by ISO/TC 213
3.2
default GPS specification
GPS specification in which the specification operator is defined by standards or regulations
Note: Where defined, default specifications are usually recognizable by the introductory wording: “unless otherwise specified...”.
3.3
ISO default GPS specification
default GPS specification defined by ISO standards
3.4
altered default GPS specification
default GPS specification defined by other means
3.5
ISO default GPS specification operator
specification operator containing only default specification operations in the default order and defined by ISO standards
4 Fundamental Assumptions for the Reading of Specifications on Drawings
4.1 General
The following assumptions regarding the interpretation of tolerance limits are the basis for the overall rules of the GPS system.
General and individual specifications written on the drawing shall always be respected and are linked by default to the assumptions given in 4.2 to 4.4.
4.2 Functional limits
It is assumed for interpretation that the functional limits are based on an exhaustive investigation done by experiment or theory, or a combination of both, so the functional limits are known with no uncertainty.
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4.3 Tolerance limits
It is assumed for interpretation that the tolerance limits are identical to the functional limits.
4.4 Workpiece functional level
It is assumed for interpretation that the workpiece functions 100% within the tolerance limits and 0% outside the tolerance limits.
5 Fundamental Principles
5.1 Invocation principle
Once a portion of the ISO GPS system is invoked in a mechanical engineering product documentation, the entire ISO GPS system is invoked, unless otherwise indicated on the documentation, e.g. by reference to a relevant document.
“Unless otherwise indicated on the documentation” means e.g. that if it is indicated on the documentation that it has been prepared in accordance with a regional, national or company standard, then that standard and not the ISO GPS system shall be used to interpret those elements of the specification that are covered by that standard.
“Tolerancing GB/T 4249” can optionally be indicated in or near the title block for information, but is not required to invoke the ISO GPS system.
Note 1: The most common way to invoke the ISO GPS system is to use one or more GPS specifications in a drawing.
Note 2: The ISO GPS system is defined in the International Standards published by ISO/TC 213. See also GB/T 20308.
Note 3: That “the entire ISO GPS system is invoked” means that e.g. fundamental and global GPS standards apply and consequently that e.g. the reference temperature given in GB/T 19765-2005 and the decision rules given in GB/T 18779.1 apply unless otherwise indicated. The purpose of the “invocation principle” is to provide the formal traceability for these GPS standards and rules.
5.2 Principle of GPS standard hierarchy
The ISO GPS system is defined in a hierarchy of standards that includes the following types of standards in the given order:
— Fundamental GPS standards
— Global GPS standards
— General GPS standards
— Complementary GPS standards.
The rules given in standards at a higher level in the hierarchy apply in all cases unless rules in standards at lower levels in the hierarchy specifically give other rules.
The rules given in fundamental GPS standards, e.g. this standard, apply in all cases, unless the rules in a specific standard at a lower level give other rules that apply within its scope.
The rules given in global GPS standards, e.g. GB/T 19765-2005, apply in all cases, unless the rules in a specific general or complementary GPS standard give other rules that apply within its scope.
All rules given in fundamental and global GPS standards apply in addition to the rules specifically given in general GPS standards, e.g. GB/T 1182, except in the cases where the rules in the general GPS standard are explicitly different from the rules given in fundamental and global GPS standards and unless the rules in a specific complementary GPS standard give other rules that apply within its scope.
All rules given in fundamental, global and general GPS standards apply in addition to the rules specifically given in complementary GPS standards, e.g. ISO 2768-1, except in the cases where the rules in the complementary GPS standard are explicitly different from the rules given in fundamental, global and general GPS standards.
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Fundamental Assumptions for the Reading of Specifications on Drawings
5 Fundamental Principles
6 Rules for Indication of Default Specification Operators
7 Rules for Indication of Special Specification Operators
8 Rules for Statements in Parentheses
Annex A (Informative) Relation to the GPS Matrix Model
Bibliography
