GB/T 4249-2018 English PDF (GBT4249-2018)

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GB/T 4249-2018: Geometrical product specifications (GPS) -- Fundamentals -- Concepts, principles and rules
GB/T 4249-2018
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
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 ON: SEPTEMBER 17, 2018
IMPLEMENTED ON: APRIL 01, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
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 
Foreword
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
Edition);
-- 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
drawings.
“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
documents”.
“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
20308.
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
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