制程能力分析

ProcessCapability制程能力

(ForOnePart,ProcessStep,orPerformanceParameter)

(对产品,工序,或表现参数)1Agenda

Objectives目标CapabilityAssessment能力评估OurProblem-SolvingOption我们问题对策的选择CapabilityAnalysisProcessMap能力分析过程图CapabilityAnalysis,Steps.能力分析、步聚TheZ-Scoreor“SigmaValue”z-值或sigma值PPM’s(PartsPerMillion)ppm`s(每百万单位数)Yield,converting%Non-conforming

unitstoYield产出，不良单位百分比转换成产出ProcessCapabilityIndices:Cp,Cpk,Pp,Ppk制程能力指数：Cp,Cpk,Pp,Ppk2CapabilityAssessment

能力评估What’sthepurposeofassessingyourproduct/processcapability?产品/制程能力评估的目的是什么？Establishmentofabaselinetomeasureimprovementagainst.

确认测量改善效果的基准Identificationofthenatureofyourproblem.问题类型的辨认Iscenteringtheissuewithyouroutputofinterest(Y)?输出(Y)问题是否处于中心？Isitprocessvariationinyouroutputofinterest(Y)?输出(Y)问题是否过程变异?Isthespecificationforyourprocessoutput(Y)correct?输出(Y)问题是否在于规格正确？Isitacombination

ofcenteringandvariation?是否是中心和变异的综合问题？3.Determinationofthegapbetweenwhereyourprocessisandwhereyouwantittobe(improvementassessment).确认过程现状与目标状态的差距(改善评估)3ProblemSolvingOptions问题解决对策Options对策CentertheMean均值处在中心ReduceVariation减少变异UpperSpecificationLimit上规格线mLowerSpecificationLimit下规格线TargetMeanCURRENT当前ExcessiveVariation过大的变异OBJECTIVEmTargetMean目标均值UpperSpecificationLimit上规格线LowerSpecificationLimit下规格线OBJECTIVE目标mLowerSpecificationLimit下规格线TargetMean目标均值UpperSpecificationLimit上规格线OBJECTIVE目标MeanoutoftargetUpperSpecificationLimitmLowerSpecificationLimitTargetValueCURRENTUpperSpecificationLimit上规格线mLowerSpecificationLimit下规格线TargetMean目标均值CURRENT当前Meanoutoftarget中心偏离目标4ProblemSolvingOptions问题解决对策MovetheSpec.Limits移规格线CentertheMeanandReduceVariation中心的均值并减少变异OBJECTIVE

目标mLowerSpecificationLimit下规格线TargetMean目标均值UpperSpecificationLimit上规格线IncorrectSpecificationCURRENTUpperSpecificationLimitmLowerSpecificationLimitTargetMeanCURRENT当前OBJECTIVEmLowerSpecificationLimit下规格线TargetMean目标均值UpperSpecificationLimit上规格线OBJECTIVE目标ExcessiveVariationandMeanoutoftarget过多的变异及均值偏离目标UpperSpecificationLimitCURRENT当前mLowerSpecificationLimitTargetMeanOptions对策5CapabilityAnalysis-ProcessMap

能力分析-过程图z-scorez-值Z-levelZ-水平Partspermillion,每百万零件数Ppm,DPMOProcesscapability过程能力Cp,Cpk,Pp,PpkYield产出1.SelecttheOutput(Y)toimprove选择输出(y)来改善2.Verifythemeasurementsystem测量系统分析(GR&R)3.Verifycustomerrequirements确认客户要求7.Calculatetheappropriatedatametrics数据处理4.Validatespecificationlimits确认规格界线5.Collectsampledata收集样品资料(IsitLTorST?是长期或短期？)6.AssessData数据评估(DescriptiveStats–Normality?描术统计-正态)?6Oneoftheprocessesinyourcompanyisrotordiecasting过程之一是转子模铸造.Theserotorsareusedinelectricmotorsproducedatyourfacility.Toestablishyourprocesscapabilityyouhaverandomlycollected30castedrotorsoverthelastfewdays.这些转子用在你们设备的电动机里，随机抽取30件最近几天浇注的转子评估制程能力CapabilityAnalysisExample能力分析举例OUTSIDEDIM.外经INTERNALDIM.内径7CapabilityAnalysis–Steps

能力分析-步聚Step1:Selecttheoutput(s)(Y’s)toimprove.步骤1：选择输出(Y)来改善(转子外表面直径)

(Outsiderotordiameter.)

Selectfrom:选择途径Businesscase市场需要Primary/Secondarymetric.关键/次要尺寸Importantinputtocontrol.重要输入(X)控制Step2:Verifythatthemeasurementsystemiscapable.步骤2：确认测量系统是可用的8CapabilityAnalysis,Steps

能力分析-步聚Step3:Verifycustomerrequirements.

步骤3：确认客户要求Consultthecustomer(Internal/External)客户沟通(内部/外部)Makesurerequirementsare:Understood,Reasonable,Measurable,Achievable.确保要求是：清楚、合理、可测量、可达到。Step4:Validatethespecification确认规格Isthedefinitionofthespecificationimportant?规格的精确度是否重要？Wheredidthespecificationcomefrom?规格的来源？Drawing?图低？Processprocedure?工艺程序？Customer?客户？9Step5:CollectaDataSample

步骤5：收集数据样品Wecollectedourdatafromcastrotorsproducedthisweekusingthethreemachineswehaveinourprocess.WehavedeterminedthatwehaveShort-Termdata.我们从生产的浇注转子收集数据，在制程中我们使用了3台机器，我们确定使用短期数据Definitions:定义：Short-Term–STsampledatacapturesasmallportionof totalvariationthataprocessmayexhibit.短期-短期样品数据来自过程可能出现所有变异中的一小部分Long-Term–LTsampledatacapturesthemajorityof variationthataprocesswillexhibit.长期-长期样品数据来自过程可能出现所有变异中的大部分Youastheprocessexpertsshouldbeinapositiontodetermineifyouaredealingwithshort-termorlong-termdata.作为一个工艺专家，你有能力决定是用短期或长期数据10SampledataisverifiedthatitfollowsaNormaldistribution.Thedataisanalyzedforinsighttohaveacluewhyisdeviatingfromnormaldistribution(outliers,distributionshape...)样品数据证实是符合正态分布，数据分析观察到存在一些不合正态分布(超出正态分布轮廓线)Step6:AssessData步骤6：数据评估P-value=>0.05,datacanbeconsideredNormallydistributedP值=>0.05，数据可认为是正态分布的11Step7:CalculateAppropriateDataMetrics步骤7：计算适当数据值

Thesearethemetricsbeingusedinindustry.Understandinghowto

convertfromonetoanotherwillimproveourcommunication.这些是用在工业中的数据值，了解相互之间转换会改善我们的沟通z-scorez-值ZLevelZ水平Parts

permillion,每百万部件数Ppm,DPMOProcesscapability过程能力Cp,Cpk,Pp,PpkYield产出RTY直通率PROCESSCAPABILITYMETRICS过程能力12Thez-scorez值Thez-score,indicateshowfarapointofinterest,isawayfromthesamplemean,measuredinstandarddeviationsunits(z).z值代表从均值到关注点的距离，用多少了标准差(z)表示。Typically,thepointofinterestisthespecificationlimit.

特别情况，关注点在规格界线上。Knowinghowmanystandarddeviationsawaythespecificationlimitiswillallowustodeterminetheamountofproductthatfallsoutsidethespecificationlimit.知道距离规格线多少标准差，我们就能确定不合格产品的数量TheSigmaLevel(Z-Level)istheequivalentz-scorewhenaddingz-scoreUSLandz-scoreLSL)

SIGMA水平(Z-水平)等于Z-值、Z-值是上控制线和下控制线Z-值相加的和。TheZ-LevelisusedasabenchmarkontheroadtoSixSigma.Z-水平是用作通向六西格玛的一个基准。13Thez-scoreZ-值

Let’scalculatesomez-scores/Zlevelsforthefollowingcases:我们来用下面一些例子计算Z值/Z水平：Case1:举例1：Non-conformingproductattheLowerSpecLimit(LSL):低于下规格线(LSL)的不格产品：3,500PPM’sNon-conformingproductattheUpperSpecLimit(USL):高于上规格线(USL)的不格产品：500PPM’s.Case2:举例2：Non-conformingproductattheLSL:1,250PPM’s

低于下规格线(LSL)的不格产品：1,250

PPM’s

Non-conformingproductattheUSL:2,250PPM’s高于上规格线(USL)的不格产品:2,250PPM’s14PPM’s(PartsPerMillion)每百万中部件数

Convertingz-scoreto%Non-conformingunits

toPPM

Z值、不合格百分比、PPM的转换Withthez-scoreweareabletoestimateproportionofnon-conformingunits.我们用Z值能得到不合格单位比例Multiplyingtheproportionofnon-conformingunits

by100weexpressitin%defective.不合格单位比例乘100，我们用不合格百分率表示ThisiswhatwedotoexpressitinPPM’s:这是我们PPM表达的原因=不合格%/100*1,000,00027,500ppm’s=不合格率*10,000=27,500ppm’s15Yield产出Converting%Non-conformances

toYield不合格百分率转换至产出Yieldisrelatedtoa%ofgoodpieces.产出是合格件数的百分率。Thisishowitiscalculated:下面是关于怎样的计算。Yield=(1–Proportionofnon-conforming

units)*100Yield=(1-不合格单位比例)*100Yield=(1-

.0251)*100=97.49%16USLLSLProcessRange制程范围SpecificationRange规格范围Target目标+3s-3sProcessCapabilityIndices:

制程能力指数

Cp,Cpk,Pp,PpkProcessCapabilityisatermtoexpresstheabilityofaprocesstomeetthespecification.制程能力是表达过程满足规范的能力ThisabilitywaschosentobemeasuredbytheproportionoftheProcessRangethatfallswithintheSpecificationRange.这个能力用来判定制程范围落在规格范围的比例Itwasalsochosentoconsiderthevariationcontainedon–3sand+3s(CpandPp)todefinetheProcessRange.它也用来考虑用包含在–3s和+3s

之间的变异(Cp和Pp)来决定制程范围Capability=DesignRange

设计范围能力ProcessRange制程范围17CpandCpkarecapabilityindicesandmeasuresthebestyourprocesscan

be,onceprocessvariationit’sreducedtoitsminimum.

Cp和Cpk

是描术过程能达成最佳值的好指标，达成过程变异的最小。CpiscalledProcessPotentialorProcessEntitlement.Cp是描述过程或潜在最佳值Cpmeasuresthebestyourprocesscanbewithoutconsideringprocessmeanlocation.Cp描述过程中最佳值、没有考虑过程均值的位置Itusesthewithinsubgroupstd.Deviation它使用短期子群的标准差SpecificationRange规格范围ProcessRange过程范围(+/-3s)0.7575ProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,Ppk18Cpkconsidersthelocationofthemean

relativetothespecificationlimits

Cpk考虑了均值的位置与规格线之间相对关系TocalculatetheCpkusetheUpperorLowerspecificationlimits,whicheverisclosesttotheprocessmean.

用上或下规格线计算

Cpk是否是离过程均值最近

Cpkusesthewithinstd.Deviation.

Cpk

使用短期标准差SpecificationRange规格范围ProcessRange(3s)过程范围=3.22696-3.226=3*0.00044=0.7272ProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,Ppk19PpandPpkareperformance

indices,measureyourprocesscurrentperformancePp和Ppk

是长期能力指数、描述当前过程表现PpandPpkformulasarethesameforCpandCpk,butusingtheOverallstddev(s)insteadofthewithin

stddev(s).Pp和Ppk计算公式与Cp和Cpk相同，但使用长期标准差代替短期标准差ProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,Ppk20

LongTerm长期

ShortTerm短期Youastheprocessexpertshouldbeinapositiontodecideifyourdatacapturesshortorlongtermprocessvariation.作为工艺专家你能确定你所获得的数据是长期或短期变异Ifthesourcesofvariationcapturedinyourdataareshortterm,thentheProcessCapabilityIndiceswillbeshortterm如果获得数据变异是短期的，那么制程能力指数是短期的Ifthesourcesofvariationcapturedinyourdataarelongterm,thentheProcessCapabilityIndiceswillbelongterm.如果获得数据变异是长期的，那么制程能力指数是长期的ProcessCapabilityIndices:过程能力指数Cp,Cpk,Pp,PpkProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,PpkProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,Ppk21CapabilityIndices:AnimprovementRoadmap能力指数：一个改进的方向MeanCentering均值移中心

MeanCentering.均值移中心Whattodotoimprove?改善做什么Goal:目标：Ppk=2ChangeProces/Technology工艺/技术更新ReduceVariationThebestyoucouldbe,withtheexistingprocess!当前工艺你能做到的

ReduceVariation减少变异ReduceVariationandMeanCenteringCpk=0.5Cp=1.4Ppk=0.3Pp=0.922ProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,PpkMinitab’sprimaryoutputonProcessCapability.Minitab过程能力的主要输出23ProcessCapabilityIndices:过程能力指数

Cp,Cpk,Pp,PpkSpecLimitsandStatisticsusedtocalculateCapabilityIndices用来计算能力指数的规格值和统计表ObservedPPM’sPerformancewiththedatacollectedonthestudy用收集的数据获得的ppm值ProcessPotentialindicesthatmeasuresthebestyourcurrentprocesscouldbe..过程长期潜在能力

ExpectedPPM’swiththePotentialPerformanceofyourCurrent

Process当前过程潜在ppmPerformanceIndicesthatmeasureyourcurrentprocess.过程长期能力

ExpectedPPM’swiththeActualPerformanceofyourCurrentProcess当前过程实际ppm24ConversionsbetweenShort-Term

andLong-Term短期和长期之间转换3.4ppmLSLUSL4.5sTOvertimeprocessshiftsby1.5stoeitherside长期过程漂移到另一边1.5sTLSLUSLProcessCentered过程中心0ppm0ppm6s

6s

4.5s1.5s1.5sThestd.whenusingthesigmalevelmetricistoassumeshorttermvariation.使用sigma水平时，设想短期变异的标准25ConversionsbetweenShort-Term

andLong-TermforUnilateralProcesses短期和长期单边过程之间转换CpkSigmaLevel(st)PPM(st)SigmaLevel(lt)PPM(lt)0.51.566,810

0.00.0500,000

0.61.835,930

0.10.3382,090

0.72.117,860

0.20.6274,280

0.82.48,200

0.30.9184,060

0.92.73,470

0.41.2115,070

1.03.01,350

0.51.566,810

1.13.3480

0.61.835,930

1.23.6160

0.72.117,860

1.33.950

0.82.48,200

1.44.213

0.92.73,470

1.54.53

1.03.01,350

1.64.81

1.13.3480

1.75.1-

1.23.6160

1.85.4-

1.33.950

1.95.7-

1.44.213

2.06.0-

1.54.53

SHORTTERM短期LONGTERM长期PpkCpk