GB/T 40742.1-2021 PDF English
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Geometrical product specifications (GPS) -- Geometrical precision verification -- Part 1: Basic concept and measurement -- Symbol, terminology, measuring conditions and procedures
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GB/T 40742.1-2021: PDF in English (GBT 40742.1-2021) GB/T 40742.1-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 17.040.40
CCS J 42
Geometrical product specifications (GPS) - Geometrical
precision verification - Part 1: Basic concept and
measurement - Symbol, terminology, measuring conditions
and procedures
ISSUED ON: OCTOBER 11, 2021
IMPLEMENTED ON: MAY 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions... 7
4 Symbols ... 8
5 Measuring conditions ... 8
6 Measurement process ... 9
Appendix A (Normative) Relevant symbols and descriptions in engineering drawings
and/or technical documents ... 13
Appendix B (Informative) Relationship to GPS matrix model ... 17
References ... 19
Geometrical product specifications (GPS) - Geometrical
precision verification - Part 1: Basic concept and
measurement - Symbol, terminology, measuring conditions
and procedures
1 Scope
This document specifies the basic concept and measurement, terminology, symbol,
measuring conditions and procedures of geometric precision verification.
This document applies to the detection and verification of geometrical characteristics
such as product size, shape, position, surface structure.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable for its application. For dated references, only the
version corresponding to that date is applicable to this document; for undated references,
the latest version (including all amendments) is applicable to this document.
GB/T 1182, Geometrical product specifications (GPS) - Geometrical tolerancing -
Tolerances of form, orientation, location and run-out
GB/T 18779.1, Geometrical Product Specifications (GPS) - Inspection by
measurement of workpieces and measuring equipment - Part 1: Decision rules for
proving conformance or non-conformance with specifications
GB/T 18779.2, Geometrical Product Specifications (GPS) - Inspection by
measurement of workpieces and measuring equipment - Part 2: Guide to the
estimation of uncertainty in GPS measurement, in calibration of measuring
equipment and in product verification
GB/T 19022, Measurement management systems - Requirements for measurement
processes and measuring equipment
GB/T 24637.1, Geometrical product specifications (GPS) - General concepts - Part
1: Model for geometrical specification and verification
GB/T 24637.2, Geometrical product specifications (GPS) - General concepts - Part
2: Basic tenets, specifications, operators, uncertainties and ambiguities
[Source: JJF 1001-2011, 4.5]
3.5
Measurement procedure
A detailed description of a measurement, based on the measurement model and the
calculations required to obtain the measurement results, according to one or more
measurement principles and the given measurement method.
Note 1: The measurement procedure is usually written in sufficient and detailed
documentation for the operator’s convenience.
Note 2: The measurement procedure may include a statement about the target
uncertainty of measurement.
Note 3: The measurement procedure is sometimes referred to as Standard Operation
Procedure (abbreviated to SOP).
[Source: JJF 1001-2011, 4.6]
4 Symbols
The relevant symbols involved in the detection and verification of geometric
characteristics such as size, shape, position, and surface structure shall comply with the
provisions of Appendix A.
5 Measuring conditions
5.1 The measuring conditions that affect the measurement results mainly include
temperature, temperature change rate, humidity, lighting, vibration, dust amount,
cleanliness, electromagnetic interference and other factors. The environmental
conditions required for the effective operation of the measurement process shall be
documented. The measuring conditions generally include measurement environmental
conditions, measurement personnel, etc. This document mainly regulates the
measurement environmental conditions.
5.2 The measuring equipment shall be used and stored under the environmental
conditions required by the specification, so that it can meet the expected operating
requirements, so as to ensure the accuracy and validity of the measurement results.
5.3 The environmental factors affecting the measurement shall be monitored and
recorded in the measurement process. When the environmental factors which affect the
measurement deviate from the specified conditions, the measurement results shall be
corrected and recorded.
5.4 When online measurement is performed at the production site, necessary measures
shall be taken to ensure that the environmental conditions meet the operating
requirements of the measuring equipment.
5.5 Unless otherwise required, the ideal environmental conditions for geometric
precision verification are as follows:
-- The standard measurement temperature is 20 °C;
-- It shall be clean and dry indoors;
-- The environmental conditions – in terms of noise, anti-vibration, dust-proof, anti-
corrosion, anti-magnetic and shielding – of the measurement room shall meet the
requirements for environmental conditions of the measurement items carried out
indoors;
-- Indoor lighting shall facilitate the measurement work.
6 Measurement process
6.1 General
The geometric precision verification objects involved in this document are mainly size,
shape, orientation, position and surface structure. During the measurement, each
measurement process shall be planned, validated, implemented, documented and
controlled, and the influence quantities that affect the measurement process shall be
identified and considered.
The complete specification of each measurement process shall include all relevant
measuring equipment identification, measurement procedures, measurement software,
conditions of use, operator capabilities and other factors affecting the reliability of the
measurement results, where the measurement procedure shall be written in sufficient
and detailed documents to guide the operator to carry out the measurement.
6.2 Measurement process design
6.2.1 General
The measurement process design shall be carried out according to the requirements of
the user, the organization and the laws and regulations. The content of measurement
process design mainly includes:
-- Definition of the measured object and the measurement task;
-- Definition of the expression form and accuracy requirements of measurement
results;
equipment); at the same time, advanced nature of the measuring equipment,
measurement efficiency, operating conditions, requirements for operators,
traceability methods for realizing the value, and economic rationality shall be
considered.
Note 2: When selecting a measurement method, consider cost and efficiency under the
premise of ensuring that the target uncertainty can be achieved (GB/T 18779.2).
Note 3: Refer to the specification requirements of GB/T 24637.2 for the design of the
inspection operation set.
Note 4: The measurement process specification document can be formulated with
reference to GB/T 19022.
6.2.5 Measurement results and verification
Operate according to the actual inspection operation set, to obtain the measurement
results, which shall include the measured value of geometric error and the uncertainty
of measurement. See GB/T 18779.2 for the evaluation, expression and management
specifications of uncertainty of measurement; perform a conformity assessment
according to the measurement results and the tolerance specification of the measured
feature, as shown in GB/T 18779.1.
6.3 Specification and implementation of the measurement process
The specification of the measurement process needs to comply with the following
requirements during the implementation process:
a) The measurement shall ensure that the measuring equipment, environmental
conditions and fixtures meet the relevant regulations in the measurement model;
b) The measurement personnel shall understand the measurement target,
measurement scheme, and be familiar with the operation of the measuring
equipment;
c) Before the measurement is carried out, it is necessary to ensure that the
preparations for the measurement – such as the preheating and calibration of the
equipment, import of the measurement model data – are completed;
d) The measurement operation process shall follow the corresponding measurement
specifications; the use of the measuring equipment shall be carried out in
accordance with the instrument manual;
e) During the measurement, in consideration of the fluctuation of the environment
(temperature, humidity, etc.) over time, monitoring measures shall be taken to
ensure that the environmental conditions are always within the allowable working
range of the measuring equipment;
f) Statistical analysis shall be carried out for the measurement results, so as to detect
deviations caused by measurement or process in a timely manner;
g) The uncertainty of measurement, which is a parameter associated with the
measurement result, shall be analyzed and evaluated.
6.4 Standardization of the measurement method
To ensure that the measurements are carried out in the same way, the measurement
method shall be standardized, and all measurements shall be carried out according to
the specified standard methods. There shall be a written document specifying all the
details of the measurement to be carried out, including how to obtain and prepare the
test piece.
The measurement method shall be a standardized and robust method, that is, the
measurement results will not produce unexpected large changes to small changes in the
measurement process. If there is a large change in the measurement process, appropriate
precautions shall be taken or a warning shall be issued. In developing a standard
measurement method, efforts shall be made to eliminate or reduce the offset of
measurement data.
Some similar test procedures can also be used to test the correctness and precision of
established and newly standardized measurement methods, where the results obtained
from the latter case should be considered as initial estimates, because the correctness
and precision vary with the accumulation of laboratory experience.
The documentation for establishing the measurement method shall be clear and
complete. All the important operations involving the procedure’s environment, reagents
and equipment, initial inspection of equipment, and preparation of test samples shall be
included in the measurement method. Measurement results and calculations, as well as
the number of significant figures shall be clearly stated.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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