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GB/T 34874.4-2025Geometrical product specifications (GPS) — X-ray three dimensional size measuring machines — Part 4: Evaluation of uncertainty in measurement (English PDF)

产品几何技术规范（GPS） X射线三维尺寸测量机第4部分：测量不确定度评定

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

March 28, 2025

Implementation date

March 28, 2025

Scope

GB/T 34874.4-2025 is the English-translated version of 产品几何技术规范（GPS） X射线三维尺寸测量机第4部分：测量不确定度评定.

GB/T 34874.4-2025 is the Chinese national standard covering putting an uncertainty figure on a dimension measured inside a part by X-ray computed tomography — the measurement task and its target uncertainty, the principle, method, operation set and conditions of the measurement, the evaluation by the GUM law of propagation and by Monte Carlo simulation, worked examples of both, and the management of the procedure over time, since a CT dimension has no surface anyone can touch to check it. Part 4 of the series, with Parts 1, 3 and 6 already published. First edition, in force from 28 March 2025. Issued on 28 March 2025, it has been in force since 28 March 2025.

Document preview — GB/T 34874.4-2025

National Standard of the People's Republic of China

ICS: 17.040.30
Classification: J 04

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

PrefaceIII
IntroductionIV
1 Scope1
2 Normative references1
3 Terms and Definitions1
4 Measurement Task1
4.1 Scope of measurement tasks1
4.2 Objectives of the measurement task and its uncertainty2
5 Measurement process2
5.1 Measurement principle2
5.2 Measurement method2
5.3 Measurement Program Operation Set3
5.4 Measurement conditions3
6 Evaluation of measurement uncertainty3
6.1 Uncertainty Assessment --- GUM Method3
6.2 Uncertainty Assessment --- Monte Carlo Method (MCM)5
7 Uncertainty management of measurement procedures7
Appendix A (Informative) Example of Measurement Uncertainty Evaluation (GUM Method)8
A.1 Overview8
A.2 Task and goal uncertainty8
A.3 Principles, methods, procedures and conditions8
A.4 Measurement Model8
A.5 Sources and explanations of measurement uncertainty9
A.6 Comments10
Appendix B (Informative) Measurement Uncertainty Evaluation Example (MCM)11
B.1 Overview11
B.2 Task and goal uncertainty11
B.3 Principles, methods, procedures and conditions11
B.4 Measurement Model11
B.5 Description of the probability distribution of each input quantity12
B.6 Reporting Results13 B.7 Comments13
Appendix C (Informative) Application of uncertainty assessment results14
Appendix D (Informative) Relationship with GPS Matrix Model15
D.1 Overview15
D.2 Information about the standard and its use15
D.3 Position in the GPS matrix model15
D.4 Related standards15
References16

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document is Part 4 of GB/T 34874 "Technical Specification for Product Geometry (GPS) X-ray Three-Dimensional Dimension Measuring Machine".

GB/T 34874 has published the following parts.

— Part 1: Vocabulary;

— Part 3: Acceptance testing and retesting;

— Part 4: Evaluation of measurement uncertainty;

— Part 6: Detection methods for workpieces.

Please note that some of the contents of this document may involve patents. The issuing organization of this document does not assume the responsibility for identifying patents.

This document is proposed and coordinated by the National Technical Committee for Standardization of Product Geometry Technical Specifications (SAC/TC240).

This document was drafted by: Shenzhen China Institute of Metrology Technology Innovation Research Institute, China Machinery Research Institute of Standards and Technology (Beijing) Co., Ltd.

China Metrology Institute, China University of Metrology, Guangdong Metrology Institute, Beijing Aerospace Metrology and Testing Technology Institute, Shenzhen Zhuomao Technology Co., Ltd., Guangzhou Metrology and Testing Technology Research Institute, Guangzhou Energy Testing Research Institute, Nanjing Metrology Supervision and Testing Institute, Anhui Chuangpu Instrument Technology Co., Ltd., Aoying Testing Technology (Shanghai) Co., Ltd., Suzhou Metrology and Testing Institute, Beijing University of Aeronautics and Astronautics Ningbo Innovation Research Institute Research Institute, Tianjin Sanying Precision Instrument Co., Ltd., and Shandong Institute of Metrology.

The main drafters of this document are: Shi Yushu, Zhu Yue, Hu Jiacheng, Song Zhenfei, Zhang Xinyu, Song Jincheng, Wang Eyu, Yan Jiewen, Wang Junxiong, Hu Liangyong, Zhang Guoke, Pi Lei, Guo Xin, Wang Yunxiang, Zhang Yong, Zhang Shu, Li Chaoyang, Shen Jin, Zhao Liang, Fu Jian, Zhang Changsheng, Lu Can, Li Junjiang, Cao Cong, Yang Shidi and Shi Zhoumiao.

Introduction

X-ray 3D dimension measuring machine is a kind of geometric measurement equipment with common application and leading technology.

As an integral part of the measurement results, the accuracy of the measurement results has a significant impact.

The measurement uncertainty evaluation method of X-ray three-dimensional dimension measuring machine is developed to ensure the accuracy of the measurement results.

The formulation of this document will also help to further improve the standard system of X-ray 3D dimension measuring machines and fill the gap in China's X-ray 3D dimension measuring machines.

It can not only promote the application of X-ray 3D dimension measuring machines by various manufacturers, but also fill the gap in the application standards of dimension measuring machines.

Unification improves the performance consistency and stability of factory equipment, and provides a solid technical foundation for the wide application of X-ray 3D dimension measuring machines.

Technical support and guarantee.

For the convenience of readers, GB/T 34874 is divided into 6 parts. The contents of these parts are interrelated and independent, and together constitute The application method of X-ray three-dimensional dimension measuring system is specified, and the relevant contents of X-ray three-dimensional dimension measuring machine are specified in detail.

GB/T 34874 is intended to consist of 6 parts.

— Part 1: Vocabulary. Aims to define the terms used in X-ray three-dimensional dimension measuring machines.

— Part 2: General technical requirements and applications. Aims to specify the basic operating requirements and applications of X-ray three-dimensional dimension measuring machines scene.

— Part 3: Acceptance test and retest. Aims to specify the inspection criteria and retest execution methods of equipment.

— Part 4: Evaluation of measurement uncertainty. Aims to provide a method for evaluating the measurement uncertainty of X-ray three-dimensional dimension measuring machines.

— Part 5: Extraction and fitting of feature elements. Aims to specify the feature extraction and data fitting methods in image processing.

— Part 6: Workpiece detection method. Aims to specify the specific operation method of the equipment in workpiece measurement.

Product Geometric Specification (GPS) X-ray 3D dimension measuring machine Part 4: Evaluation of measurement uncertainty

1 Scope

This document describes a method for evaluating the measurement uncertainty of X-ray 3D dimension measuring machines.

This document is applicable to the measurement uncertainty assessment of X-ray three-dimensional dimension measuring machines.

2 Normative references

GB/T 18779.2

GB/T 27418

GB/T 27419

GB/T 34874.1

JJF1001

3 Terms and definitions

The terms and definitions defined in GB/T 18779.2, GB/T 27418, GB/T 27419, GB/T 34874.1 and JJF1001 apply to this document.

4 Measurement tasks

4.1 Scope of measurement tasks

As a non-destructive testing technology equipment, X-ray 3D dimension measuring machine has a wide range of measurement tasks, including but not limited to the following aspects.

— Internal structure measurement. It can penetrate the object being tested and has high spatial resolution to obtain its internal structure, shape and size.

And other information, suitable for the detection of various complex structures;

— External structure measurement. With high spatial resolution, it can obtain information such as the external structure, shape and size of the object being tested.

For the detection of various complex structures;

— Three-dimensional data reconstruction. Through CT, DR, 3D and other imaging methods, it is possible to achieve three-dimensional reconstruction of the object being measured, providing a more direct More comprehensive test results.

Although X-ray 3D dimension measuring machines have powerful measuring capabilities, their measuring range is also limited by the instrument itself and other conditions. The system mainly includes.

a) Object size and load. The maximum scanning range and maximum load of the equipment are fixed and should be operated according to the requirements specified by the equipment manufacturer.

Scanning angle and weight limit are performed;

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 20 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 34874.1Geometrical product specifications (GPS) - X-ray three dimensional size measuring machines - Part 1: Vocabulary

GB/T 18779.2 · GB/T 27418 · GB/T 27419 · JJF1001

Editions of GB/T 34874.4

Edition	Title	Revision	Status
GB/T 34874.4-2025	Geometrical product specifications (GPS) - X-ray three dimensional size measuring machines - Part 4: Evaluation of uncertainty in measurement	current edition	Current

This page sells the current edition, GB/T 34874.4-2025. Earlier editions are listed for reference only.

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