ASME_B1.25-2019.pdf

AN AM E R IC AN NAT IO NAL STANDARDASME B1.25-2019Measurement Uncertainty Factors in the Calibration of Screw Thread GagesASME B1.25-2019MeasurementUncertainty Factors inthe Calibration ofScrew Thread GagesAN AMERICAN NATIONAL STANDARDxDate of Issuance:May 24,2019ThenexteditionofthisStandardisscheduledforpublicationin2024.ThisStandardwillbecomeeffective1yearaftertheDateofIssuance.Periodically certain actions of the ASME B1 Committee may be published as Cases.Cases are published on the ASME websiteunder the B1 Committee Page at http:/go.asme.org/B1Committee as they are issued.Errata to codes and standards may be posted on the ASME website under the Committee Pages to provide corrections toincorrectlypublisheditems,ortocorrecttypographicalorgrammaticalerrorsincodesandstandards.Sucherratashallbeusedon the date posted.TheB1CommitteePagecanbefoundathttp:/go.asme.org/B1Committee.Thereisanoptionavailabletoautomaticallyreceivean e-mail notification when errata are posted to a particular code or standard.This option can be found on the appropriateCommittee Page after selecting“Errata”in the“Publication Information”section.ASME is the registered trademark of The American Society of Mechanical Engineers.ThiscodeorstandardwasdevelopedunderproceduresaccreditedasmeetingthecriteriaforAmericanNationalStandards.TheStandardsCommitteethatapprovedthecodeorstandardwasbalancedtoassurethatindividualsfromcompetentandconcernedinterestshavehadanopportunityto participate.The proposed codeorstandardwasmadeavailable forpublic reviewandcommentthatprovidesanopportunityfor additional public input from industry,academia,regulatory agencies,and the public-at-large.ASME does not“approve,”“rate,”or“endorse”any item,construction,proprietary device,or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in thisdocument,anddoesnotundertaketoinsureanyoneutilizingastandardagainstliabilityforinfringementofanyapplicableletterspatent,norassumeanysuchliability.Usersofacodeorstandardareexpresslyadvisedthatdeterminationofthevalidityofanysuchpatentrights,andtherisk of infringement of such rights,is entirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted as government or industryendorsement of this code or standard.ASME accepts responsibility for only those interpretations of this document issued in accordance with the established ASME proceduresand policies,which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronicretrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersTwo Park Avenue,New York,NY 10016-5990Copyright 2019 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword.ivCommittee Roster.vCorrespondence With the B1 Committee.vi1Introduction.12Scope.13Definitions.14Calibration Equipment Considerations.25Factors to Be Included in Uncertainty Budgets.46Measurement Uncertainty Examples.67Dispute Resolution.68How Measurement Uncertainty Affects Acceptance.79Uncertainty/Tolerance Rules.810Reporting Uncertainty.811Special Requirements.912References.9Figures6-1One Measurement Showing Its Associated Range of Uncertainty.66-2Two Measurements With Differing Uncertainties.66-3Identical Measurements With Different Uncertainties.76-4Different Measurements With Different Uncertainties.78-1Effect of Uncertainty on an At-Limit Measurement.88.1-1Acceptable Measurements That Ignore Uncertainty.88.2-1Acceptable Measurements That Include Uncertainty.88.3-1Two Measurements With Unacceptable Uncertainties.9iiiFOREWORDTheincreasingdemandforregularcalibrationofequipmentusedtoensuredimensionalconformityinmanufacturinghas created corresponding growth in the number of calibration facilities to meet it.This in turn has brought morestringentrequirementsforthosedoingsuchwork,includingarequirementforastatementofmeasurementuncertaintyapplicable for each measurement reported.PublicationssuchastheASMEB1TechnicalReportMeasurementUncertaintyfor60deg.ScrewThreadGageElementMeasurement were produced to assist in evaluating the impact of uncertainty for gage calibration.Unfortunately,thevaluesshowninASMEB1wereoftenadoptedasgenericinnatureeventhoughequipmentandproceduresbeinguseddidnot match those on which the indicated values were based.This led to wide variations in reported uncertainties anddisagreementsovermeasurements.ThisStandardreplacestheB1TechnicalReportbyprovidingagenericbasethatcanbe used for uncertainty calculations.While the calculations used to produce uncertainty values are well documented,the elements that have to be consid-ered require knowledge of metrology in keeping with the specialized nature of precision gage calibrations and thestandardstowhichprecisiongagecalibrationdevicesaremade.Thisisparticularlycritica