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GB/T 4249-2018 PDF in English

GB/T 4249-2018 (GB/T4249-2018, GBT 4249-2018, GBT4249-2018)
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GB/T 4249-2018: PDF in English (GBT 4249-2018)

GB/T 4249-2018
ICS 01.100.20
J 04
Replacing GB/T 4249-2009
Geometrical product specifications (GPS) -
Fundamentals - Concepts, principles and rules
(ISO 8015:2011, MOD)
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 5 
4 Basic assumptions for reading specification on drawing ... 6 
5 Basic principles ... 7 
6 Marking rules for default specification operator ... 12 
7 Marking rules for specific specification operator ... 14 
8 Rules described in brackets ... 16 
Annex A (informative) Positions in GPS matrix model ... 17 
Bibliography ... 19 
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 4249-2009 “Geometrical product specifications
(GPS) - Tolerancing principle”. Compared with GB/T 4249-2009, the main
technical changes in this Standard are as follows:
-- deleted, added some terms and definitions (see Clause 3 of this Edition,
Clause 3 of Edition 2009);
-- moved the content of “Independent principle” to the clause of
“Fundamental principle” (see 5.5 of this Edition, Clause 4 of Edition 2009);
-- deleted tolerance (see Clause 5 of Edition 2009);
-- deleted relevant requirements (Clause 6 of Edition 2009);
-- deleted drawing marks of tolerance principle (Clause 7 of Edition 2009);
-- added basic assumptions for reading specification on drawing (see Clause
4 of this Edition);
-- added basic principle (see Clause 5 of this Edition);
-- added marking rules for default specification operator (see Clause 6 of this
-- added marking rules for specific default specification operator (see Clause
7 of this Edition);
-- added rules for expression in brackets (see Clause 8 of this Edition).
This Standard uses redrafting method to modify and adopt ISO 8015:2011
“Geometrical product specifications (GPS) -- Fundamentals -- Concepts,
principles and rules”.
Compared with ISO 8015:2011, there are technical differences in this Standard.
The terms involved in these differences have been marked by a vertical single
line (-) at the margin of the outer margin. The corresponding technical
differences and reasons are as follows:
-- for normative references, this Standard made adjustment for specific
technical differences, so as to adapt to the technical conditions of China.
See Clause 2 “Normative references” for the adjustment. The specific
adjustments are as follows:
• used GB/Z 24637.1 that identically adopts International standard to
Geometrical product specifications (GPS) -
Fundamentals - Concepts, principles and rules
1 Scope
This Standard specifies the fundamental concepts, principles and rules that are
valid for the creation, interpretation and application of all relevant standards,
technical specifications and technical documents to product dimensions,
geometrical product specifications (GPS) and inspections.
This Standard is applicable to the interpretation for GPS marks on all types of
“Drawing” referred in this Standard is a broad concept. It includes all documents
that express workpiece specifications.
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 (GB/Z
24637.1-2009, 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 purposes of this document, the terms and definitions defined in GB/Z
24637.1, GB/Z 24637.2, ISO/IEC Guide 98-3:2008, ISO/IEC Guide 99:2007 as
It is assumed that the interpretation for the tolerance limit is completely same
with the interpretation for the functional limit.
4.4 Functional level of workpiece
It is assumed that the workpiece 100% meets the function within the tolerance
limit; does not meet the function outside the tolerance limit.
5 Basic principles
5.1 Principle for adoption
Once it adopts one part of ISO GPS system in mechanical engineering product
documents, it is equivalent to adopting the entire ISO GPS system, unless
otherwise stated in the document, for example, “refer to other related
“Unless otherwise stated in the document” means that if the regional, national
or enterprise standards referred are marked in the document, it shall use those
standards. Do not adopt ISO GPS system to interpret the normative elements
specified in the standard.
If it is unnecessary to adopt ISO GPS system, “noting method is according to
GB/T 4249” may selectively mark within the title bar or near the title bar.
NOTE 1: The most common way to adopt ISO GPS system is to use one or more GPS
specifications in drawing.
NOTE 2: ISO GPS system is an International standard issued by ISO/TC 213, see GB/T
NOTE 3: “Adopting the entire ISO GPS system” means that unless otherwise specified, if
GPS fundamental standard and GPS comprehensive standard are adopted, then the
reference temperature specified in GB/T 19765-2005 and the rules for determination
specified in GB/T 18779.1 shall be adopted. The purpose of “principle for adoption” is to
provide formal traceability for those GPS standards and rules.
5.2 Principle for hierarchy of GPS standard
ISO GPS system is hierarchical. Its standard variety, according to hierarchy,
contains the following types:
- GPS fundamental standard;
- GPS comprehensive standard;
- GPS general standard;
5.4 Key element principle
One workpiece can be considered to be composed by many key elements that
are limited by natural boundaries. Under the situation of default, each GPS
specification of one key element applies to the entire key element. Each GPS
specification that expresses the relationship between many key elements
applies to many key elements. Each GPS specification is only applicable to one
key element or one relationship between key elements.
If it is necessary to change this default specification, it needs to clearly mark on
the drawing.
NOTE 1: The natural boundaries between key elements usually refer to the boundaries
that sudden change happens on the surface normal. But it is not always true. If one
workpiece is composed of two hemispherical elements that have same diameter and
intermediate cylindrical element, in such case, the surface normal of natural boundaries
between key elements does not have sudden change.
NOTE 2: Some marks do not apply to the entire key element, for example, partial area of
key element is marked with a long thick dotted line or is marked with ACS (any cross
NOTE 3: Some marks apply to many key elements, for example, CZ (combined tolerance
zone) is marked.
NOTE 4: Unless otherwise specified, GPS general specification is considered as a series
of GPS specifications. Each GPS specification is only applicable to one characteristic of
key element or relationship between key elements (see 5.12).
5.5 Independence principle
Under the situation of default, GPS specification of each key element or GPS
specification of relationship between key elements is independent from other
specifications. They shall be met respectively, unless other standards or special
marks are specified in the actual product specification (for example, modifier
symbol ○M in GB/T 16671, CZ in GB/T 1182 and ○E in ISO 14405-1).
5.6 Decimal point principle
The numerical values after the decimal point of nominal size and tolerance
value that are not indicated shall be zero. This principle is applicable to the
drawing and GPS standard.
Example 1: ±0.2 is equivalent to ±0.200000...
Example 2: 2:10 is equivalent to 10.000000...
5.7 Default principle
eliminate any ambiguity of the functional description in the specification.
A complete specification operator defines every important detail to be measured
for the specification. Therefore, it eliminates the ambiguity of the specification.
Inspection of operation is an actual application of specification operator. When
the method uncertainty is zero, inspect the sequences of operator and
specification operator which shall be in one-to-one correspondence. When the
method uncertainty is not zero, there are differences in two operators or the
sequence of two specifications.
Although the inspection operator is not marked in the drawing, it shall get close
to the specification operator during the inspection process, so as to ensure the
method uncertainty within the allowable range.
5.10.2 Description of duality principle
The duality principle points out:
a) the GPS specification operator that is specified by GPS specification is
irrelevant to any measuring procedures or measuring instruments;
b) the inspection operator that is to realize GPS specification operator is
irrelevant to the GPS specification itself; but the relationship between it
and GPS specification operator is mirror correspondence.
GPS specification does not specify which kind of inspection operator is
acceptable. Whether the operator is acceptable or not is inspected by
measuring the uncertainty and specification uncertainty.
5.11 Function control principle
The function of each workpiece is described by function operator. It can be
simulated by a series of specification operators. These specification operators
once again define a series of measuring and relevant tolerances.
When all functional requirements of workpiece have been clearly described and
controlled by GPS specification, such specification is complete. In most cases,
since some functions are described / controlled imperfectly, the specification
might be incomplete. Therefore, the correlation between function and a series
of GPS specifications may be superior or inferior.
Any correlation deficiency between any functional requirements and GPS
specification shall cause the uncertainty of function description.
5.12 General specification principle
For each characteristic that has same type and the relationship between each
When the actual specification of any geometric characteristic in the drawing is
ISO basic GPS specification that is marked according to GB/T 1182, GB/T 131-
2006, GB/T 17851, and when in or near title bar, altered default general GPS
specification is not marked, then ISO default specification operator is required
by a current ISO standard that defines corresponding default specification
operator. When establishing drawing, the ISO standard that specifies
corresponding default specification operator shall be the latest version. If other
earlier versions of ISO standard are required to use, it shall be indicated clearly.
NOTE: At present, ISO GPS standard does not give default provisions on all specification
operations in all specification operators, so some ISO default specification operators are
6.3 Altered default GPS specification
One altered default specification operator shall be defined in relevant document.
As a part of a complete specification operator, altered default specification
operator shall be rigorously, clearly and completely defined.
Altered default specification operator shall be marked in or near title bar of
drawing. When non-ISO GPS standard is applied, it shall at least mark the
following information:
- indicate “marking method” or “marking method is according to GB/T 4249”;
- symbol ;
- complete identifier of relevant document and other necessary information
(such as date of release).
NOTE: AD represents “altered default”.
If altered default specification operator in drawing is more than one, a number
is needed to add after each symbol.
Some ISO standards provide to adopt altered ISO default mode, for example
“Size ISO 14405 ”.
symbol only applies to non-ISO GPS standard.
defined in default specification operator.
NOTE 1: The type of the added supplementary information (requirements) shall be defined
by specification modifier (see GB/Z 24637.2).
According to ISO basic specification, in the marked specific specification
operator, the operator that is not specified by the supplementary provisions
shall be still defined by default specification.
NOTE 2: At present, ISO GPS standard does not give default provisions on all specification
operations in all specification operators, so some ISO basic specifications are incomplete.
The contents specified in 7.2 shall be applied to the marks of the following two
specific specification operators:
- testing key elements that are comply with GB/T 1182, GB/T 131-2006, GB/T
17851 respectively;
- unique default specification of drawing.
7.2 Additional supplementary information (requirements) of ISO basic
When necessary, the additional supplementary information (requirements) of
ISO basic specification can change the default operation of ISO basic
specification, for example:
a) fitting rule;
b) filter type;
c) transmission band;
d) probe tip;
e) extraction condition.
When these default specifications are changed for specific design needs, ISO
basic specification shall use the following modes to modify:
- for GB/T 1182, add information to the second block of the tolerance marking
- for GB/T 131-2006, add information in a~e areas of graphic symbol that the
surface structure is complete;
- for ISO 14405-1, add modifier to tolerance mark.
See corresponding standards for details.
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.