ANSI ASME B89.7.2-2014 Dimensional Measurement Planning.pdf

1、AN AMERICAN NATIONAL STANDARD ASME B89.7.2-2014Revision of ASME B89.7.2-1999 (R2004)Dimensional Measurement PlanningASME B89.7.2-2014Dimensional Measurement PlanningAN AMERICAN NATIONAL STANDARDRevision of ASME B89.7.2-1999 (R2004)Two Park Avenue New Yo rk, NY 10016 USADate of Issuance: December 29,

2、 2014This Standard will be revised when the Society approves the issuance of a new edition.ASME issues written replies to inquiries concerning interpretations of technical aspects of this Standard. Interpretations are published on the Committee Web page and under go.asme.org/InterpsDatabase. Periodi

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11、ed in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersTwo Park Avenue, New York, NY 10016-5990Copyright 2014 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.iii

12、CONTENTSForeword ivCommittee Roster viCorrespondence With the B89 Committee vii1 Scope . 12 Definitions 13 Normative References . 24 Dimensional Measurement Planning . 25 Dimensional Measurement Plan Approval 36 Dimensional Measurement Plan Application 37 References 3Nonmandatory AppendicesA Sample

13、Dimensional Measurement Plan . 5B Gage Selection 17C Dimensional Measurement Uncertainty 21D Probabilities of Pass and Fail Errors . 29ivFOREWORDThe intent of this Standard is to facilitate agreement between suppliers and customers by specifying a standard method for assessing the dimensional accept

14、ability of workpieces. Components of the method are the preparation of an adequate dimensional measurement plan and the use of the plan in making measurements. Major inputs to the method are dimensional specifications developed, for example, in compliance with ASME Y14.5-2009, Dimensioning and Toler

15、ancing 1.The first publication of ASME Y14.5 was a significant step forward in manufacturing because it defined methods for the unambiguous expression of design intent on workpiece drawings. ASME Y14.5 specifies design intent in terms of workpiece features (e.g., cylinders, planes, spheres, etc.). A

16、 feature is dimensioned and toleranced by specifying boundaries within which the infinite number of points on the feature surface must lie (for surface geometries) or by specifying a boundary within which the axes must lie (axes control). Any adequate assessment of whether a manu-factured feature co

17、mplies with an ASME Y14.5 drawing specification must consider this infinite number of points.In the early days of ASME Y14.5, serious attempts to determine compliance of workpiece features with drawing specifications were based on gaging by attributes, e.g., by means of ring gages, plug gages, and f

18、unctional gages. Such gages dealt with the infinite number of points by means of gaging surfaces, which were intended as the ideal counterparts of the surfaces to be measured. Uncertainty due to gage imperfections was minimized by specifying gages whose probable errors were tightly controlled when c

19、ompared with the tolerances of the workpieces to be measured. Gage dimensions were biased to ensure that no nonconforming workpieces were accepted, even though such biasing resulted in the rejection of some conforming workpieces.In 1994, a supporting standard was released that explicitly defined the

20、 mathematical expression of ASME Y14.5, which was ASME Y14.5.1M-1994, Mathematical Definition of Dimensioning and Tolerancing Principles 7. This Standard presents a mathematical definition of geometrical dimensioning and tolerancing consistent with the princi-ples and practices of ASME Y14.5M-1994,

21、enabling determination of actual values.Since the capability of a typical manufacturing process has improved more rapidly than the measurement capability associated with gaging by attributes, the old methods have led to expensive increases in the rejection of conforming workpieces. Statistical analy

22、sis capabilities and cost effectiveness have led to the proliferation of coordinate-meas-uring machines (CMMs) that cannot directly verify dimensional acceptability using an infinite number of points in a workpiece feature surface but account for this in the associated measurement uncertainty statem

23、ent. In some instances, the algorithms used to associate substitute geometrical elements according to drawing specifications result in significant measurement uncertainty. ASME Working Group B89.3.2 (now B89.7.2) was formed to address these and related issues.One of these issues is the criterion for

24、 acceptable dimensional measurement practice. A measurement process should be designed to balance measurement quality and cost, including costs associated with decision outcomes resulting in rejecting conforming products or accepting nonconforming products due to the measurement uncer-tainty. While

25、the analysis of costs is workpiece-specific and outside the scope of this dimensional measurement Standard, the measurement process should be designed to provide the required metrological data for the risk analy-sis needed to formulate a decision rule.Measurement quality is characterized in terms of

26、 measurement uncertainty. Previous practice has been to assume that gage quality was controlled to a level where the contribution to measurement uncertainty due to gaging error was negligible. This assumption was applied both to measurement by attributes, as described above, and to measure-ment by v

27、ariables using simple bench tools such as micrometers and height gages. Gage repeatability and reproduc-ibility (GR however, they should not contain proprietary names or information.Requests that are not in this format may be rewritten in the appropriate format by the Committee prior to being answer

28、ed, which may inadvertently change the intent of the original request.ASME procedures provide for reconsideration of any interpretation when or if additional information that might affect an interpretation is available. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME

29、 Committee or Subcommittee. ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construc-tion, proprietary device, or activity.Attending Committee Meetings. The B89 Standards Committee regularly holds meetings and/or telephone confer-ences that are open to the public. Persons wishing

30、to attend any meeting and/or telephone conference should contact the Secretary of the B89 Standards Committee. Future Committee meeting dates and locations can be found on the Committee Page at go.asme.org/B89committee.viiiINTENTIONALLY LEFT BLANKASME B89.7.2-20141DIMENSIONAL MEASUREMENT PLANNING1 S

31、COPE1.1 ObjectiveThe objective of this Standard is to ensure correctness and acceptability of dimensional measurements.1.2 RequirementsThis Standard specifies requirements for preparation and approval of dimensional measurement plans and for the use of approved plans in making dimensional measuremen

32、ts.1.3 ApplicabilityThis Standard considers that a dimensional measure-ment method is acceptable if its associated measure-ment uncertainty per the Guide to the Expression of Uncertainty in Measurement (GUM) 2 meets business needs, e.g., cost of measurements, consequences of pass and fail errors, li

33、ability, specific policies, and customer requirements. In assessing the acceptability of a stated measuring procedure, management should take into account the importance and difficulty of evaluating measurement uncertainty in such a way as to quanti-tatively capture the effects of all significant so

34、urces of measurement error.1.4 PurposeThis Standard is intended for use by process and qual-ity engineers or personnel performing a similar function in planning dimensional measurements.2 DEFINITIONSaccept-reject measurement: measurement made for the purpose of accepting or rejecting a workpiece or

35、work-piece feature or property.attribute gage: gage that verifies conformance of a work-piece property with a specified requirement without yielding a measured value.conforming: having a true value lying within or on the boundary of a stated tolerance interval.NOTE: The issue of conformance/nonconfo

36、rmance involves where the true value of the measurand lies with respect to the tolerance zone; the issue of acceptance/rejection involves where a measured value lies with respect to the acceptance zone.consumers risk: probability of a pass error.dimensional measurement: measurement of a geometrical

37、property of a workpiece.dimensional measurement plan: plan detailing equipment, environment, and procedure for measuring one or more geometrical properties of a workpiece or for measuring the properties of a process.dimensional measurement planner (DMP): person who pre-pares a dimensional measuremen

38、t plan.fail error: rejection, as a result of measurement uncer-tainty, of a conforming property of a process or a workpiece.NOTE: A fail error is also known as false rejection or a Type 1 error.failure mode and effects analysis (FMEA): for a system, the steps of listing failure modes and determining

39、 effects of failure on the system in each mode.feature: general term applied to physical portion of a workpiece, such as a surface, hole, or slot.gaging limits: specified limits of a measured value of a workpiece property.NOTE: Gaging limits are also known as acceptance limits.geometric characterist

40、ic: dimensional description of a feature.manufacturing plan: plan detailing organization, equip-ment, environment, personnel, and procedures for man-ufacturing a workpiece.measurand: quantity intended to be measured.nonconforming: having the true value lying outside the boundaries of a stated tolera

41、nce interval.ASME B89.7.2-20142NOTE: The issue of conformance/nonconformance involves where the true value of the measurand lies with respect to the tolerance zone; the issue of acceptance/rejection involves where a measured value lies with respect to the acceptance zone.pass error: acceptance, as a

42、 result of measurement uncer-tainty, of a nonconforming property of a process or a workpiece.NOTE: A pass error is also known as false acceptance or a Type 2 error.process control measurement: measurement of the features or properties of sampled workpieces in order to detect a change in the process.

43、process failure: change or changes in a process resulting in production of unacceptable workpieces.producers risk: probability of a fail error.tolerance: total amount a specific dimension is permit-ted to vary. The tolerance is the difference between the maximum and minimum limits.NOTE: The toleranc

44、e interval is the region between and including the tolerance limitsuncertainty (of measurement): non-negative para meter characterizing the dispersion of the values being attributed to a measurand, based on the information used.NOTE: Uncertainty is different from the measurement error, which is the

45、difference between the measured value and the true value.3 NORMATIVE REFERENCESASME B89.7.3.1-2001, Guidelines for Decision Rules: Considering Measurement Uncertainty in Determining Conformance to SpecificationsASME B89.7.3.2-2007, Guidelines for the Evaluation of Dimensional Measurement Uncertainty

46、ASME B89.7.3.3-2002, Guidelines for Assessing the Reliability of Dimensional Measurement Uncertainty StatementsASME B89.7.4.1-2005, Measurement Uncertainty and Conformance Testing: Risk AnalysisASME B89.7.5-2006, Metrological Traceability of Dimensional Measurements to the SI Unit of LengthASME Y14.

47、5-2009, Dimensioning and TolerancingASME Y14.5.1M-1994, Mathematical Definition of Dimensioning and Tolerancing PrinciplesPublisher: The American Society of Mechanical Engineers (ASME), Two Park Avenue, New York, NY 10016-5990; Order Department: 22 Law Drive, P.O. Box 2900, Fairfield, NJ 07007-2900

48、(www.asme.org)JCGM 100:2008, Evaluation of measurement data Guide to the expression of uncertainty in measurement (GUM)JCGM 200:2012, International vocabulary of metrology Basic and general concepts and associated terms (VIM)Publisher: Joint Committee for Guides in Metrology, Bureau International de

49、s Poids et Mesures, Pavillon de Breteuil, F-92312 Svres Cedex, France (www.bipm.org/en/publications/guides)4 DIMENSIONAL MEASUREMENT PLANNING4.1 GeneralFor each workpiece to be measured, a dimensional measurement plan shall determine and define necessary measurement tasks and shall specify their requirements.(a) Necessary measurement tasks can be process con-trol measurements, accept-reject measurements, or both.(b) Each process control measurement should relate to a controllable parameter of the workpiece manufac-turing process.4.2 Prerequisites4.2.1 Dimension