博世汽车SPC资料.pdf

博世汽车SPC资料.pdf

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4thEdition,07.20053rdEditiondated06.19942ndEditiondated05.19901stEditiondated09.19872005RobertBoschGmbH-3-TableofContentsIntroduction.51.TermsforStatisticalProcessControl.62.Planning.82.1SelectionofProductCharacteristics.82.1.1TestVariable.82.1.2Controllability.92.2MeasuringEquipment.92.3Machinery.92.4TypesofCharacteristicsandQualityControlCharts.102.5RandomSampleSize.112.6DefiningtheIntervalforTakingRandomSamples.113.DeterminingStatisticalProcessParameters.123.1TrialRun.123.2Disturbances.123.3GeneralCommentsonStatisticalCalculationMethods.123.4ProcessAverage.133.5ProcessVariation.144.CalculationofControlLimits.154.1Process-RelatedControlLimits.154.1.1NaturalControlLimitsforStableProcesses.164.1.1.1ControlLimitsforLocationControlCharts.164.1.1.2ControlLimitsforVariationControlCharts.184.1.2CalculatingControlLimitsforProcesseswithSystematicChangesintheAverage.194.2AcceptanceControlChart（Tolerance-RelatedControlLimits）.204.3SelectionoftheControlChart.214.4CharacteristicsoftheDifferentTypesofControlCharts.225.PreparationandUseofControlCharts.235.1ReactionPlan（ActionCatalog）.235.2PreparationoftheControlChart.235.3UseoftheControlChart.235.4EvaluationandControlCriteria.245.5WhichComparisonsCanbeMade?

.256.QualityControl,Documentation.266.1Evaluation.266.2Documentation.26-4-7.SPCwithDiscreteCharacteristics.277.1General.277.2DefectTallyChartfor100%Testing.278.Tables.289.ExampleofanEventCodeforMechanicallyProcessedParts.299.1Causes.299.2Action.299.3HandlingoftheParts/Goods.309.4ActionCatalog.3010.Exampleofanx-sControlChart.3211.Literature.3312.Symbols.34Index.35-5-IntroductionStatisticalProcessControl（SPC）isaprocedureforopenorclosedloopcontrolofmanufacturingprocesses,basedonstatisticalmethods.Randomsamplesofpartsaretakenfromthemanufacturingprocessaccordingtoprocess-specificsamplingrules.Theircharacteristicsaremeasuredandenteredincontrolcharts.Thiscanbedonewithcomputersupport.Statisticalindicatorsarecalculatedfromthemeasurementsandusedtoassessthecurrentstatusoftheprocess.Ifnecessary,theprocessiscorrectedwithsuitableactions.Statisticalprinciplesmustbeobservedwhentakingrandomsamples.ThecontrolchartmethodwasdevelopedbyWalterAndrewShewhart（1891-1967）inthe1920sanddescribedindetailinhisbook“EconomicControlofQualityofManufacturedProduct”,publishedin1931.Therearemanypublicationsandself-studyprogramsonSPC.Theproceduresdescribedinvariouspublicationssometimesdiffersignificant-lyfromRBprocedures.SPCisusedatRBinacommonmannerinalldivisions.TheprocedureisdefinedinQSP04021inagreementwithallbusinessdivisionsandcanbepresentedtocustomersastheBoschapproach.CurrentquestionsonuseofSPCandrelatedtopicsarediscussedintheSPCworkgroup.ResultsthatarehelpfulfordailyworkandofgeneralinterestcanbesummarizedandpublishedasQAInformationsheets.SPCisanapplicationofinductivestatistics.Notallpartshavebeenmeasured,aswouldbethecasefor100%testing.Asmallsetofdata,therandomsamplemeasurements,isusedtoestimateparametersoftheentirepopulation.Inordertocorrectlyinterpretresults,wehavetoknowwhichmathematicalmodeltouse,whereitslimitsareandtowhatextentitcanbeusedforpracticalreasons,evenifitdiffersfromtherealsituation.Wedifferentiatebetweendiscrete（countable）andcontinuous（measurable）characteristics.Controlchartscanbeusedforbothtypesofcharacteristics.Statisticalprocesscontrolisbasedontheconceptthatmanyinputscaninfluenceaprocess.The“5Ms”man,machine,material,milieu,methodaretheprimarygroupsofinputs.Each“M”canbesubdivided,e.g.milieuintemperature,humidity,vibration,contamination,lighting,.Despitecarefulprocesscontrol,uncontrolled,randomeffectsofseveralinputscausedeviationofactualcharacteristicvaluesfromtheirtargets（usuallythemiddleofthetolerancerange）.-6-Therandomeffectsofseveralinputsideallyresultinanormaldistributionforthecharacteristic.ManysituationscanbewelldescribedwithanormaldistributionforSPC.Anormaldistributionischaracterizedwithtwoparameters,themeanandthestandarddeviation.Thegraphofthedensityfunctionofanormaldistributionisthetypicalbellcurve,withinflectionpointsatand+.InSPC,theparametersandofthepopulationareestimatedbasedonrandomsamplemeasurementsandtheseestimatesareusedtoassessthecurrentstatusoftheprocess.1.TermsforStatisticalProcessControlProcessAprocessisaseriesofactivitiesand/orproceduresthattransformrawmaterialsorpre-processedparts/componentsintoanoutputproduct.Thedefinitionfromthestandard3is:

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