ASTM E2281-2008a 能力指数处理和测量的标准实施规程

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【英文标准名称】:StandardPracticeforProcessandMeasurementCapabilityIndices
【原文标准名称】:能力指数处理和测量的标准实施规程
【标准号】:ASTME2281-2008a
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E11.30
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:
【英文主题词】:long-termvariability;processcapability;processcapabilityindices;processperformance;processperformanceindices;short-termvariability;Capabilityindices;Long-termvariability;Observation/observedvalues;Performance--laboratoryinstrumen
【摘要】:ProcessCapability8212;Processcapabilitycanbedefinedasthenaturalorinherentbehaviorofastableprocessthatisinastateofstatisticalcontrol(1).Ax201C;stateofstatisticalcontrolx201D;isachievedwhentheprocessexhibitsnodetectablepatternsortrends,suchthatthevariationseeninthedataisbelievedtoberandomandinherenttotheprocess.Processcapabilityislinkedtotheuseofcontrolchartsandthestateofstatisticalcontrol.Aprocessmustbestudiedtoevaluateitsstateofcontrolbeforeevaluatingprocesscapability.ProcessControl8212;Therearemanywaystoimplementcontrolcharts,butthemostpopularchoiceistoachieveastateofstatisticalcontrolfortheprocessunderstudy.Specialcausesareidentifiedbyasetofrulesbasedonprobabilitytheory.Theprocessisinvestigatedwheneverthechartsignalstheoccurrenceofspecialcauses.Takingappropriateactionstoeliminateidentifiedspecialcausesandpreventingtheirreappearancewillultimatelyobtainastateofstatisticalcontrol.Inthisstate,aminimumlevelofvariationmaybereached,whichisreferredtoascommoncauseorinherentvariation.Forthepurposeofthisstandard,thisvariationisameasureoftheuniformityofprocessoutput,typicallyaproductcharacteristic.ProcessCapabilityIndices8212;Thebehaviorofaprocess(asrelatedtoinherentvariability)inthestateofstatisticalcontrolisusedtodescribeitscapability.Tocompareaprocesswithcustomerrequirements(orspecifications),itiscommonpracticetothinkofcapabilityintermsoftheproportionoftheprocessoutputthatiswithinproductspecificationsortolerances.Themetricofthisproportionisthepercentageoftheprocessspreadusedupbythespecification.Thiscomparisonbecomestheessenceofallprocesscapabilitymeasures.Themannerinwhichthesemeasuresarecalculateddefinesthedifferenttypesofcapabilityindicesandtheiruse.Twoprocesscapabilityindicesaredefinedin5.2and5.3.Inpractice,theseindicesareusedtodriveprocessimprovementthroughcontinuousimprovementefforts.Theseindicesmaybeusedtoidentifytheneedformanagementactionsrequiredtoreducecommoncausevariation,compareproductsfromdifferentsources,andtocompareprocesses.ProcessPerformanceIndices8212;Whenaprocessisnotinastateofstatisticalcontrol,theprocessissubjecttospecialcausevariation,whichcanmanifestitselfinvariouswaysontheprocessvariability.Specialcausescangiverisetochangesintheshort-termvariabilityoftheprocessorcancauselong-termshiftsordriftsoftheprocessmean.Specialcausescanalsocreatetransientshiftsorspikesintheprocessmean.Eveninsuchcases,theremaybeaneedtoassessthelong-termvariabilityoftheprocessagainstcustomerspecificationsusingprocessperformanceindices,whicharedefinedin6.2and6.3.Theseindicesaresimilartothoseforcapabilityindicesanddifferonlyintheestimateofvariabilityusedinthecalculation.Thisestimatedvariabilityincludesadditionalcomponentsofvariationduetospecialcauses.Sinceprocessperformanceindiceshaveadditionalcomponentsofvariation,processperformanceusuallyhasawiderspreadthantheprocesscapabilityspread.Thesemeasuresareusefulindeterminingtheroleofmeasurementandsamplingvariabilitywhencomparedtoproductuniformity.1.1Thispracticeprovidesguidancefortheuseofcapabilityindicesforevaluatingprocesscapabilityandperformance.Processcapabilityindicescomparethevariabil......
【中国标准分类号】:N04
【国际标准分类号】:25_040_40
【页数】:8P.;A4
【正文语种】:英语