ASME B89 7 5-2006 Metrological Traceability of Dimensional Measurements to the SI Unit of Length《长度国际单位制尺寸测量的计量溯源(ASME 技术报告)》.pdf
《ASME B89 7 5-2006 Metrological Traceability of Dimensional Measurements to the SI Unit of Length《长度国际单位制尺寸测量的计量溯源(ASME 技术报告)》.pdf》由会员分享,可在线阅读,更多相关《ASME B89 7 5-2006 Metrological Traceability of Dimensional Measurements to the SI Unit of Length《长度国际单位制尺寸测量的计量溯源(ASME 技术报告)》.pdf(14页珍藏版)》请在麦多课文档分享上搜索。
1、Metrological Traceability of Dimensional Measurements to the SI Unit of LengthASME B89.7.5-2006(Technical Report)ASME B89.7.5-2006(Technical Report)MetrologicalTraceability ofDimensionalMeasurements to theSI Unit of LengthThree Park Avenue New York, NY 10016Date of Issuance: July 17, 2006This Techni
2、cal Report will be revised when the Society approves the issuance of a new edition. Therewill be no addenda issued to this edition.ASME is the registered trademark of The American Society of Mechanical Engineers.ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device
3、, or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with anyitems mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent, nor assume
4、 any such liability. Users of a code or standard are expresslyadvised that determination of the validity of any such patent rights, and the risk of infringement of such rights, isentirely their own responsibility.Participation by federal agency representative(s) or person(s) affiliated with industry
5、 is not to be interpreted asgovernment or industry endorsement of this code or standard.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park A
6、venue, New York, NY 10016-5990Copyright 2006 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword ivCommittee Roster . viAbstract . 11 Introduction 12 Requirements for Metrological Traceability of Dimensional Measurements 23 Details of Dimensional Metrol
7、ogical Traceability 34 Examples of Demonstrating Metrological Traceability . 3iiiFOREWORDThe ISO Guide to the Expression of Uncertainty in Measurement (GUM) is now the internation-ally accepted method to express measurement uncertainty 1. The U.S. has adopted the GUMas a national standard 2. The eva
8、luation of measurement uncertainty has been applied for sometime at national measurement institutes, but more recently, issues such as measurement traceabilityand laboratory accreditation are resulting in its widespread use in calibration laboratories.Given the potential impact on business practices
9、, national and international standards commit-tees are working to publish new standards and technical reports that will facilitate the integrationof the GUM approach and consideration of measurement uncertainty. In support of this effort,ASME B89 Committee on Dimensional Metrology has formed Divisio
10、n 7: Measurement Uncer-tainty.Measurement uncertainty has important economic consequences for calibration and measure-ment activities. In calibration reports, the magnitude of the uncertainty is often taken as anindication of the laboratory quality, and smaller uncertainty values generally are of hi
11、gher valueand cost. ASME B89.7.3.1, Guidelines for Decision Rules: Determining Conformance to Specifica-tions 3, addresses the role of measurement uncertainty when accepting or rejecting productsbased on a measurement result and product specification. ASME B89.7.3.2, Guidelines for theEvaluation of
12、Dimensional Measurement Uncertainty 4, provides a simplified approach (relativeto the GUM) to the evaluation of dimensional measurement uncertainty. ASME B89.7.3.3, Guide-lines For Assessing the Reliability of Dimensional Measurement Uncertainty Statements 5,examines how to resolve disagreements ove
13、r the magnitude of the measurement uncertaintystatement. Finally, ASME B89.7.4.1, Measurement Uncertainty And Conformance Testing: RiskAnalysis 6, provides guidance on the risks involved in any product acceptance/rejection decision.Historically, measurement traceability was an effort to ensure accur
14、acy through paperwork;the requirement to show calibration reports forced instruments and standards to be calibrated.The International Vocabulary of Basic and General Terms in Metrology (VIM) 7 definition oftraceability now requires a GUM-compliant uncertainty statement that provides a quantitativeac
15、curacy statement of the measurement result, a significant improvement over a calibration reportnumber.The VIM definition does not specify the requirements regarding the “stated references,” i.e.,measurement standards, or what constitutes an appropriate terminus for the “unbroken chainof comparisons.
16、” In a standard on “General requirements for the competence of testing andcalibration laboratories,” ISO 17025 8 states (in para. 5.6.2.1.1), “A calibration certificate bearingan accreditation body logo from a calibration laboratory accredited to this International Standard,for the calibration conce
17、rned, is sufficient evidence of traceability for the calibration data reported.”In this report, the concept of traceability developed in ISO 17025 is used as the basis to extendbeyond calibration laboratories and into the industrial metrology domain.The ambiguity in the VIM definition of what consti
18、tutes a reference standard and what consti-tutes an unbroken chain of comparisons leads to multiple interpretations. Some practitionersbelieve that the only appropriate terminus for a reference standard must be a national or interna-tional standard. Others believe any calibration certificate will su
19、ffice. Similarly, which uncertaintycomponents must have “an unbroken chain of comparisons” is also unclear, e.g., dimensionalmeasurements often involve numerous influence quantities, such as temperature, force, physicalconstants, or any of a large number of other parameters that appear in the uncert
20、ainty budget.Such a chain could easily be very complex.More fundamentally, the entire concept of an unbroken chain is blurred when uncertainty isevaluated using the GUM. The GUM permits Type B evaluations, which are based on “expertjudgment,” and these terminate not at the SI unit but in the mind of
21、 the “expert.” In the measure-ment of large workpieces, the uncertainty of the thermal expansion coefficient can be the singlelargest component of the uncertainty budget, and the value of the expansion coefficient togetherwith its uncertainty is almost always guessed. Since a GUM uncertainty evaluat
22、ion can allowivthe largest contributor to the measurement uncertainty to have documentary traceability only tothe mind of the expert, providing extensive paperwork documenting the calibration history ofother subsidiary influence quantities involved in the measurement is of limited value.Upon reviewi
23、ng beliefs regarding the intent of metrological traceability, it is clear the conceptmust span a wide variety of applications, from the highest level calibration laboratories toshop floor measurements of production workpieces. Furthermore, any requirements must beeconomically practical and not gener
24、ate substantial paperwork that adds little value to themeasurement result. Accordingly, while ASME B89.7.5 requires the assessment of all significantuncertainty sources in the uncertainty statement, the additional requirement that the principallength standard(s) must have documentation traceability
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