工程方法_6sigma_09工序能力分析.ppt

CapabilityAnalysis过程能力分析,MPTConfidential,Page2,测量阶段流程图,流程图(Processmapping),C“6Sigma”水平;IntroductiontoZ-scoreZ-值介绍ProcessCapabilityforNon-NormalData非正态分布的过程能力Cycle-Time(ExponentialDistribution)循环时间(指数分布)RejectRate(BinomialDistribution)不合格(剔除)率(二项式分布)DefectRate(PoissonDistribution)缺陷率(泊松分布),MPTConfidential,Page4,ProcessControlvsProcessCapability过程控制和过程能力,1.ProcessControl过程控制Meanstheprocessisoperatinginstatisticalcontrol,moncausesaretheonlysourceofvariation.意味是过程在稳定状态下生产,也就是说,一般原因(偶然原因)是变异的唯一原因Refersto“voiceoftheprocess”,i.e.oneonlyneedsdatafromtheprocesstodetermineifaprocessisincontrol.起源于”过程的声音”,也就是说,唯一来源于过程的数据来判定过程是否受控.Trackperformanceoftheprocesstoverifyifitformsastabledistributionovertime,typicallywithacontrolchartwithcontrollimitscomputedfromtheprocessdataonly.随着时间过去,反馈过程的表现来验证它是否来自于一个稳定的分布,一般地,利用从过程数据计算控制界限的控制图来完成.Justbecauseaprocessisincontroldoesnotnecessarilymeanitisagoodprocess.仅仅因为过程受控并不一定说它是个好过程.,MPTConfidential,Page5,2.ProcessCapability过程能力The“goodness”ofaprocessismeasuredbyprocesscapability过程的“好坏”是过程能力测量的Compares“voiceoftheprocess”with“voiceofthecustomer”,whichisgivenintermsofspecs.orrequirements比较“过程声音”和“客户声音”,哪一个是根据规格或需要给出的?Measureshowwellastabledistribution(processincontrol)matchesupwithcustomersspecs.测量一个稳定的分布(过程受控)符合客户规格的程度.,ProcessControlvsProcessCapability过程控制和过程能力,首先判定过程稳定,确定数据分布是正态的,再计算过程能力和西格码质量水平.,MPTConfidential,Page6,WhatisCapability过程能力是.,Whenprocessisundercontrol,capabilityisdecidedbycustomerdemandandprocessperformance(Productorservicequalityshiftingdegree).Themoretheprocessmeetsthecustomerneed,thebetterthecapabilitywillbe.过程在受控状态下时,客户要求与过程表现(产品品质或服务的品质变动程度)的比值,如果过程表现越能满足客户要求,则过程能力越充分,反之则不足.,MPTConfidential,Page7,ProcessCapability过程能力,ProcessCapabilitystudiescan过程能力研究可以:indicatetheconsistencyoftheprocessoutput显示过程输出的稳定性indicatethedegreetowhichtheoutputmeetsspecifications表明输出满足规格的程度beusedforcomparisonwithanotherprocessorcompetitor可以与另一过程或竟争对手相比较,MPTConfidential,Page8,ProcessVariation过程变异,ProcessVariationistheinevitabledifferencesamongindividualmeasurementsorunitsproducedbyaprocess.过程变异是不可避免的差别在单个测量或过程生产单位之间.SourcesofVariation变异的来源:withinunit产品内(positionalvariation)位置的变异betweenunits单位之间(unit-unitvariation)产品-产品的变异betweenlots产品批之间(lot-lotvariation)批批的变异betweenlines生产线之间(line-linevariation)线-线之间的变异acrosstime不同时间(time-timevariation)时间-时间的变异measurementerror测量误差(repeatability=1,),Exponential(x;),ProcessCapabilityforCycleTime周期时间的过程能力,MPTConfidential,Page69,Example4,Acustomerservicemanagerwantstodeterminetheprocesscapabilityforhisdepartment.Aprimaryperformanceindexisthetimetakentocloseacustomercomplaint.Thegoalforthisindexistocloseacomplaintwithinonecalendarweek.Performanceoverthelast400complaintswasreviewed.,一位客户服务经理想确定他的部门过程能力,主要评价指标为处理客户投诉的时间周期,目标为在一周内处理完一单客户投诉,过去的400%次投诉作为测量数据.数据在此期01-03Days,MPTConfidential,Page70,Example4,StatQualityToolsCapabilityAnalysis(Weibull),MPTConfidential,Page71,Example4,MPTConfidential,Page72,Example4A,StatQualityToolsCapabilitySixpack(Weibull),MPTConfidential,Page73,Example4A,MPTConfidential,Page74,AlternativesforNon-NormalData非正态数据解释,Whenallothermethodsfail,itmaybenecessarytofallbackonasimpleassessmentofthetotalamountoutofspecifications.Simplycountthenumberofdefectiveunitsanddividebythetotaltocomputethefractiondefective.AnotherstandardmetricforthisistheDPPM.当所有方法失败,它需要返回到一个评估超出控制界限数量的简单方法,简单地查一下不合格品和全部产品的数量,然后计算不合格率,另一个标准刻度也是DPPMIfaCapabilityIndexmustbereported,theDPPMcanbeconvertedbackintoaZvalue,andtheneitherPpk=Z/3orCpk=Z/3dependinguponwhetherthedataislongtermorshortterm.如果要得到过程能力指数,DPPM可以转化为Z-值,然后根据此数据是长期或短期得PPK=Z/3或Cpk=Z/3,MPTConfidential,Page75,ProcessCapabilityforRejectRate不合格率的过程能力,ForaNormalDistribution,theproportionofpartsproducedbeyondaspecificationlimitis对于一个正态分布,在控制界限下的比例部分.,RejectRate,MPTConfidential,Page76,Thus,foreveryrejectratethereisanaccompanyingZ-Score,这样一来,对于每一个不合格率都有一个对应的Z-值Where这里Recallthat原先Hence因此,ProcessCapabilityforRejectRate不合格率的过程能力,MPTConfidential,Page77,EstimationofPpkforRejectRate不合格率Ppk的计算:Determinethelong-termrejectrate(p)计算长期不合格率(p)Determinetheinversecumulativeprobabilityforp,usingCalcProbabilityDistributionNormal计算相反的累计概率p,点击CalcProbabilityDistributionNormalZ-ScoreisthemagnitudeofthereturnedvalueZ-值是反推值的多少.Ppkisone-thirdoftheZ-ScorePpk是Z-值的三分之一.,ProcessCapabilityforRejectRate不合格率的过程能力,MPTConfidential,Page78,ExampleofProcessCapabilityStudyforRejectRate不合格率过程能力的例子,Asalesmanagerplanstoassesstheprocesscapabilityofhistelephonesalesdepartmentshandlingofincomingcalls.一个销售经理打算评估他的电话销售部门处理接入电话的过程能力.01-03文件Thefollowingdatawascollectedoveraperiodof20days:以下数据收据20天numberofincomingcallsperday每天的接入电话数量numberofunansweredcallsperdays每天的未应答电话数量.,MPTConfidential,Page79,StatQualityToolsCapabilityAnalysis(Binomial),ExampleofProcessCapabilityStudyforRejectRate不合格率过程能力的例子,MPTConfidential,Page80,ExampleofProcessCapabilityStudyforRejectRate不合格率过程能力的例子,MPTConfidential,Page81,ProcessCapabilityforDefectRate缺陷率的过程能力,Otherapplications,approximatingaPoissonDistribution:errorratesparticlecountchemicalconcentration,以下应用,近似于泊淞分布:缺陷率缺点数溶液浓度,MPTConfidential,Page82,EstimationofYtpforDefectRateDefinesizeofaninspectionunitDeterminethelong-termdefectsperunit(DPU)DPU=TotalDefectsTotalUnitsDeterminethethroughputyield(Ytp)Ytp=expDPU,ProcessCapabilityforDefectRate缺陷率的过程能力,评价缺陷率的Ytp确定检查单元的大小确定长期单位缺陷数(DPU)DPU=TotalDefectsTotalUnits确定(Ytp),MPTConfidential,Page83,EstimationofSigma-CapabilityforDefectRate评估缺陷率的Sigma能力Determinetheopportunitiesperunit确定每个产品单元的机会数Determinethelong-termdefectsperopportunity(d)确定每个机会的长期缺陷数(dd=defectsperunitopportunitiesperunitDeterminetheinversecumulativeprobabilityford,计算相反的累计概率值dusingCalcProbabilityDistributionNormalZ-ScoreisthemagnitudeofthereturnedvalueZ-值是反推值的多少.Sigma-Capability=Z-Score+1.5,ProcessCapabilityforDefectRate缺陷率的过程能力,MPTConfidential,Page84,Example6,Theprocessmanagerforawiremanufacturerisconcernedabouttheeffectivenessofthewireinsulationprocess.Randomlengthsofelectricalwiringaretakenandtestedforweakspotsintheirinsulationbymeansofatestvoltage.Thenumberofweakspotsandthelengthofeachpieceofwirearerecorded.1inspectionunitisdefinedas125unitlengthofwire.,某线材制造商的工程经理关注线材绝缘过程的有效性.随机长度的导线被通过加压测试绝缘不良点.不良点数和每段线的长度都做以记录.一个检查单元定为125单位长度的导线.01-03文件weakspot,MPTConfidential,Page85,Example6,StatQualityToolsCapabilityAnalysis(Poisson),MPTConfidential,Page86,Example6,DefectsperUnit=0.0265194ThroughputYield=expDPU=exp0.0265194=0.9738c.f.First-TimeYield=2