质量管理七大手法-wurooney

QC7ToolsWhatis7tools??ChecksheetLeveldiagramHistogramParetodiagramCause-and--effectdiagramScatterdiagramControlchartImportanceof7toolsWhy““MADEINJAPAN””----Automobile,electronic,chemical,exactitudeequipment,,etc.Theconcept““QC7tools”israisedbyKaoruIshikawa.“QC7tools”playedanimportantpartinJapan’seconomicrecoveryanddevelopment.QC7Tools----CheckSheetWhatischecksheet?Atablewhichlistsoutallitemsneedchecking.Checksheetincludes,butnotlimitedto:diagnoses,,questionnaire,,record,statistics,etc.CheckSheet----KeypointsKeypoints:1.Verifytheitemstocheck;2.Verifythefrequencytocheck;3.Verifythepersonneltocheck.Implementprocedure1.Verifytheobject;2.Framethechecksheet;;3.Checkandrecord;4.RequestaimprovementaimingattheNCitems5.Verifytheimprovement6.Summarizeperiodicallyandimprovepersistently.LevelDiagramWhatisleveldiagram??Sortallopinions,viewsorthoughtsbyspecifictopicandgroupthecollecteddataorinformation.Implementprocedure1.Identifythetopictostudy;;2.Frametheleveldiagramandcollectdata;3.Sortthedatatovariouslevels;4.Analyzethedata.QC7Tools----HistogramWhatishistogram?Ahistogramisasimplefrequencydistribution.Itisaplotoftheactualdatashowingthedatavaluesversusthenumberofoccurrencesforeachvalue.JudgetheProcessCapability(Cp)fromthehistogramCpisjustOKCpisbetterthanspecCpisleantoleftCpisleantorightTooscatteredCpImplementProcedure1.Collectdata;;Forexample:GeardimensionproducedbyABCfactoryasbelow;specificationofthisgearis24..5±6mm:1234567891022.123.422.627.722.923.724.521.324.721.225.824.523.221.321.624.124.817.421.920.323.924.624.322.724.626.730.026.023.124.622.821.822.624.025.122.419.323.923.621.525.023.624.924.826.423.926.618.323.225.321.725.023.521.724.327.229.025.023.822.322.228.024.621.625.224.826.727.628.525.824.625.322.527.525.524.824.623.818.819.925.124.822.626.624.125.023.420.621.326.322.924.421.523.123.428.922.4ImplementProcedure2.Counttherange::R=Xmax–Xmin=30.0--17..4=12.63.Setthegroup:Totaldata50-100100-250>250Groups6-107-1210-20Weset10groupsinthisexample.Implementprocedure4.Verifytheminmeasurementunit:Itisdecidedbydecimaldigits.Minimummeasurementunitinthisexampleis0..1.5.Counth;h=R//10==12..6/10=1.26≈1.3Implementprocedure6.Counttheupperlimitandlowerlimit:Lowerlimitoffirstgroup=17.4-(minmeasurementunit/2)=17.4-0..1/2=17.35;Lowerlimitof2ndgroup=17.35+1.3==18..65;;DetailUpper//lowerlimit::1stgroup:17.35-18.65;2ndgroup:18.65-19.953rdgroup:19.95-21.25;……9thgroup:27.75-29.05;10thgroup:29.05-30.35Implementprocedure7.Countmedian;;Groupmedian==(Groupupperlimit+Grouplowerlimit))/21stgroupmedian==(17.35+18.65)/2=18.00Therestmaybededucedbyanalogy.Implementprocedure8.Fillfrequencytable:groupUpper/lowerlimitvalueMedianFrequencies117.35-18.6518.002218.65-19.9519.303319.95-21.2520.605421.25-22.5521.9016522.55-23.8523.2020623.85-25.1524.5029725.15-26.4525.8012826.45-27.7527.108927.75-29.0528.4041029.05-30.3529.7019.Drawhistogram.Implementprocedure10.Analyzethehistogram.Thishistogrambelongstonormaldistribution,,sotheprocessisconsideredasstable.QC7tools----ParetoDiagramWhatisParetodiagram?Itisadiagrambasedonhistogramandusedtoidentifythe““criticalminor””.Paretodiagramcanbeusedtofindoutthemajorproblemonquality,cost,leadtime,,safety((phenomenon);;operator,machine,material,working((process)..ParetodiagramprocedureTakethedefectsfoundinafigureproductionforexample,,total15854products,including216defectives..1.Collectdata2.Sortorder(descending),andcountaccumulativepercentage.NoCategoryDefectDefect%AccumulativeDefect%1DirtMark7534.7%34.7%2Paintmigration4721.8%

56.5%

3Scratchmark3918.1%74.5%4Excessiveflash2813%87.5%5Insufficientglue177.9%95.4%6Whitemark73.2%98.6%7Other31.4%100.0%Total∑216100.0%100.0%Paretodiagramprocedure3.DrawXaxisandYaxisandmarkingscale.4.Drawhistogram.5.Drawaccumulativecurve.6.AnalyzeParetodiagramandtakecorrectiveaction.((Veryimportant)).QC7tools----Cause-and--effectdiagramWhatisCause-and-effectdiagram?Itisatooltoanalyzethequalitycharacteristics((effect)andthepotentialfactortoeffectthecharacteristics(cause)..Keypoints1.PersonnelfromdifferentDept;2.Analyzethecauseasdetailaspossible;;3.Eachqualitycharacteristicneedsacause-and--effectdiagram;;4.Verifytheproblemcanbesolvedornot;;ifnot,subdividethecause.ImplementProcedure1.3-6variousdeptrepresentativestoformagroup;;2.Topic:forexample,,whydoesdimensionofgearvary??3.Drawouttherib,setthemajorcauseWhydoesdimensionofgearvary?ManMachineMaterialMethodEnvironmentImplementProcedure4.Findoutthedetailcauseandaddtothediagram((“BrainStorm”isrecommended));5.Markthecausethatmaybetherootoftheproblemandtakecorrectiveaction.Whydoesdimensionofgearvary?ManMachineMethodEnvironmentMaterialWrongoperationNotenoughtrainingNotimelycheckingPatrolintervaltoolongLaxdisciplineInsufficienthardnessVarioushardnessDifferentsuppliersImpurematerialEquipmentprecisionHardtoadjustInstablevoltagePoorfixtureNotimelymaintenanceNooperationinstructionNoiseTemperaturevariesInsufficientlightAnalysisFindout3majorproblems:1.Material:5differentsuppliers,notthesamequality,andnotstable;;2.Person::Newworkers,notenoughtrainingresultsinwrongoperation;3.Method::NoWIorWIcontentnotrelatedtoactualwork..QC7Tools----ScatterDiagramWhatisscatterdiagram?AdiagramtofindoutwhetherthereisanyrelationshipbetweentwovariablesbyplottingthedatainX-Yaxlecoordinates.TypesofscatterdiagramGenerallythereare4typesofscatterdiagram:Positivecorrelation((X↑,,Y↑↑);Negativecorrelation((X↑,,Y↓↓);Nocorrelation;Curvecorrelation.Keypoint1.Checkifthereisabnormaldot,,findoutthecauseoftheabnormal;;2.Datashouldbeenough((atleast>30)3.Asdataisalwaysvaryingduetoman,,machine,,material,method,,environment,etc,,weshouldsortthedatatoavoideffect.((leveldiagram)).Implementprocedure1.Verifythe2variablestocheckandcollectthedata(atleast30groups));2.MarkthedotontheX--Ycoordinates;3.Judgetherelationship.ExampleScatterdiagramofmotorcontinuousoperationtime((T)andvelocity(V):Fig..4TVTVTVTVTV133073251325019210251712320828514244202042616533089300152372119727159431110270162312219128151530411264172252318529145629712257182182417830133QC7Tools----ControlChartWhatiscontrolchart??Controlchartsareameansofgraphingvariationpatternsfromprocessorproductcharacteristicssothatcorrectiveactionmaybetakenifrequired.NormaldistributionNormaldistributionisacurveofwhichthecenterisprotruded,,twosidesofthecurvearelowerandsymmetrical.Weusetwoparametertodescribethenormaldistribution;μ(Meanvalue)andσ(standarddeviation).Parameterμandσμμ’μ<μ’Thenormalcurvemovestorightwhenμincreases..σ=2.5σ=1.0σ=0.4Qualitycharacteristicsbecomemorescatteredaccompaniedwiththeincreaseofthevalueofσ.TheoreticbasistosetUCLandLCLTheCentralline(CL)ofcontrolchartisthemeanvalue;UpperControlLimit((UCL)ismeanvalue+3σandLowerControlLimitismeanvalue-3σ.+3σ+2σ+1σ-1σ-2σ-3σCLUCLLCLRelationshipbetweenσanddefectivepercentage1σ2σ3σ4σ5σ6σ69.77%30.87%6.68%6210PPM233PPM3.4PPM*Consideringinfluencesfromvariousfactors.*4.5σrepresents1350ppmdefectives.Comparing6σand3σ,defectivepercentagereduced20,,000times!Motorolarequesthissupplierprovideproductswith6σquality;

3σand6σ…3σ6σMissing20,000E-mailperhourMissing7E-mailperhour15minutesunsafedrinkingwaterperday1minuteunsafedrinkingwaterper7months5000incorrectsurgicalperweek1.7incorrectsurgicalperweekTwicewronglandingonmainairportperdayOncewronglandingonmainairportper5years20,000wrongprescriptionperyear68wrongprescriptionperyear7hourspowercutpermonth1hourpowercutper34yearsWhichkindofcontrolcharttochoose?Howtochoosecontrolchart?TotalSizeAttributeCharacteristicCLPropertyX-RmChartSampleSizeUnitSizecChartuChartnpChartpChartSampleSizex–RChartx–σChartx–RChartVariablesAttributes1UnitDefectivesDefectsStableVaryfixedVaryxxn<1010≤n≤25Implementprocedure1.Collectdata;;Generallydatashouldbe≥100..2.Groupthedata;Groupinto25groups,5data//group..3.Countxmeanandtotalxmean.x=(x1+x2+……++xn)/nx=∑xi/nImplementprocedure4.Countrange((R)ofeachgroupandmeanofrange((R);;