NOKIA生产过程控制全球培训教材（三）

CpandCpkIndicesandDefects

(bothtailsofthenormaldistribution)Pp=Ppk=1,3363ppmdefects=0,006%Cp=Cpk=1,670,6ppmdefects=0,00006%Note:

PpmrejectratescalculatedfromCp&CpkarebasedontheshorttermvariationwhichmaynotrepresentthelongtermrejectrateTheEffectsofCpkandCponFFRExercise2:CpandCpkCalculateCpandCpkforthe100measurementsinthefile"Dataexercise1.xls"DeterminetheapproximateCpandCpkforthe4samplepopulationsonthefollowingpageShouldactionsbemadetoimprovetheseprocesses.Ifyes,which?EstimateCpandCpk?Thewidthofthenormaldistributionsshowninclude±3*sLSLUSLA)LSLUSLB)LSLUSLC)USLLSLD)EstimateCpandCpk?-A)LSLUSLA)MeanandnominalUSL-LSL6*sUSL-MeanMean-LSL3*sEstimateCpandCpk?-B)LSLUSLB)NominalMeanUSL-LSL6*sUSL-MeanMean-LSL3*sEstimateCpandCpk?-C)LSLUSLC)NominalMeanUSL-LSL6*sUSL-MeanMean-LSL3*sEstimateCpandCpk?-DUSLLSLD)NominalMeanUSL-LSL6*sUSL-MeanMean-LSL3*sSection4.UseoftheNMPDataCollectionSpreadsheetExampleofhowtoCollectData

1. Runinandstabiliseprocess2. Notethemainparametersforreference3. Whentheprocessisstablerunthetoolfor10hours3. Take5partsoutfromeachcavityeveryhalfhourandmarkthemwithtime,dateandcavity.Total20setsof5partsfromeachcavitymustbemade,oraccordingtoagreement.4. Afterthelastsamplelotnotethemainprocessparametersforreference5. Measureandrecordthemainfunctionalcharacteristics(whitediamonds)6. FilldataintotheNMPdatacollectionspreadsheet7. Analyse!SeeDMY00019-ENClassificationandMarkingofFunctionalCharacteristicsTimeDimensionSubgroupsizen=5NumberofsubgroupsN=200,5hoursbetweensamplestakenNote:Forclarity,only6subgroupsareshownDataCollectionSheet(DMM00024-EN-5.0)DataCollectionSheet(DMM00024-EN-5.0)GraphicalPresentation:HistogramWhatkindofdistribution?LocationversustoleranceareaWidth(deviation)Example: Cp 2.59 Pp 1.86

Cpk 0.88 Ppk 0.63GraphicalPresentation:X-barandR-ChartX-BarChartR-ChartGraphicalPresentation-TimeSeriesPlotSomethinghappenedhere!!!Exercise3:CpkDataSpreadsheetOpenspreadsheet"Dataexercice3.xls".Dim13isidenticaltothedatafromthepreviousexercises.Verifytheresultsfromthepreviousexercisesfordimension13.Analysetheremainingdatasetsancommenttheprocess,shouldanyactionsbemade?Remembertocreateandlookatthecharts.Section5.

ConfidenceofCpkConfidenceofCpkCpkvaluesarenotdefinitenumbersastheyarebasedonrelativelysmallsamplesofapopulation.The95%confidenceintervaldeterminestheintervalwhichincludesthetrueCpkvaluewithaprobabilityof95%,i.e."thereisaprobabilityof5%thatCpkiseitherlowerorhigher"thanthisconfidenceinterval.95%confidenceintervalActualcpkCpkupperconfidencelimitCpklowercon