ASME_B89.7.3.1-2001.pdf

ASME B897.3200GUIDELINES FOR DECISION RULES-CONSIDERING MEASUREMENTUNCERTAINTIN DETERMINCONFORMANCE TOPECIFIGATIONSAN AMERICAN NATIONAL STANDARDE米S)The American Society ofineersNot tor ResaleThe American Society ofMechanical EngineersA N AM E RI C AN N A T ION A L S TA N D A R DGUIDELINES FOR DECISION RULES:CONSIDERING MEASUREMENTUNCERTAINTY IN DETERMININGCONFORMANCE TOSPECIFICATIONSASME B89.7.3.1-2001No reproduction or networking permitled without Fcense from IHSNot for ResaleDate of Issuance:March 18,2002This Standard will be revised when the Society approves the issuance of anew edition.There will be no addenda issued to this edition.ASME will issue written replies to inquiries concerning interpretation oftechnical aspects of this Standard.ASME is the registered trademark of The American Society of Mechanical Engineers.This code or standard was developed under procedures accredited as meeting the criteria forAmerican National Standards.The Standards Committee that approved the code or standardwas balanced to assure that individuals from competent and concerned interests have had anopportunity to participate.The proposed code or standard was made available for public reviewand comment that provides an opportunity for additional public input from industry,academia,regulatory agencies,and the public-at-large.ASME does not approve,rate,or endorseany item,construction,proprietary device,or activity.ASME does not take any position with respect to the validity of any patent rights asserted inconnection with any items mentioned in this document,and does not undertake to insure anyoneutilizing a standard against liability for infringement of any applicable letters patent,nor assumeany such liability.Users of a code or standard are expressly advised that determination of thevalidity of any such patent rights,and the risk of infringement of such rights,is entirely theirown responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not tobe interpreted as government or industry endorsement of this code or standard.ASME accepts responsibility for only those interpretations of this document issued inaccordance with the established ASME procedures and policies,which precludes the issuanceof interpretations by individuals.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 Avenue,New York,NY 10016-5990Copyright2o02byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll Rights ReservedPrinted in U.S.A.No reproduction or netwrorking permitted without lcense from IHSNot for ResaleFOREWORDThe intent of these guidelines is to facilitate the development of understanding betweensuppliers and customers regarding measurement uncertainty in the decision to accept or toreject a product.Metrologists are continuously faced with the task of making decisions inthe presence of measurement uncertainty.To formalize this task,procedures known asdecision rules have been developed.A decision rule is a prescription for the acceptanceor rejection of products based on the measurement result of a characteristic of the product,the permissible variation associated with that characteristic,and the uncertainty of themeasurement result.For workpieces,the permissible variation is commonly called thetolerance;for instruments it is often given by the specification limits or maximum permissibleerror(MPE).The terminology of ISO 14253-1 has been adopted and the permitted variationof a products characteristic is referred to as the specification zone.This document isintended to provide guidance on decision rules and their implementation.A related document,ASME B89.7.2-1999,Dimensional Measurement Planning,specifiesrequirements for preparation and approval of dimensional measurement plans and for theuse of approved plans in making dimensional measurements.The dimensional measurementplan must contain or reference all information for making measurements,including specificationof a decision rule.ASME B89.7.3.1 serves as a resource to the dimensional measurementplanner by providing terminology and specifying the requirements for decision rules foruse in dimensional measurement plans.The Guide to the Expression of Uncertainty in Measurement,(GUM),NCSL Z540-2-1997 provides a unified means of evaluating and expressing the uncertainty of a measurementresult;consequently the calculational details of evaluating the uncertainty of a measurementresult will not be discussed.Unless otherwise stated,the term measurement uncertaintywill be used to mean the expanded uncertainty,U,with a coverage factor of two,whichis the most common coverage factor used nationally and internationally.Although all traceable measurement results include an uncertainty statement not allmeasurement results involve decision rules.(See ISO International Vocabulary of Basic andGeneral Terms in Metrology.)Many calibrations,particularly at National MeasurementInstitutes(NMIs),typically state a description of the measurement,its result,and itsuncertainty;decision rules are not involved since there are no specifications.Most products,however,have stated specifications and a decision must be reached regarding the productscharacteristic relative to its stated specifications.The decision rule in use should be well documented to prevent ambiguity in the acceptanceor rejection of product.The selection of a particular decision rule is ultimately a businessdecision;some of the factors to be considered are outlined in nonmandatory AppendicesA and D.The concept of a decision rule has a long history and over the years has developedmany variations including gauge makers rule,test accuracy ratio(TAR),test uncertaintyratio(TUR),“four-to-one rule,.”“gauging ratio,.”“guard bands,“gauging limit,”and manymore.Most of these terms were defined before the development of the GUM and henceconcepts such as accuracyor uncertaintywere nebulously defined.One of the motivationsof these guidelines is to explicitly define the decision rule concept and have some well-documented decision rules that can be referenced.Consequently,these guidelines haveencapsulated some of the commonly used procedures and their specifically-named deci-sion rules.e with ASMENo reproduction or networking permitlod without licenso from IHSNot for Resale