质量管理七大手法--wurooney.ppt

QC7Tools,Whatis7tools?,ChecksheetLeveldiagramHistogramParetodiagramCause-and-effectdiagramScatterdiagramControlchart,Importanceof7tools,Why“MADEINJAPAN”-Automobile,electronic,chemical,exactitudeequipment,etc.Theconcept“QC7tools”israisedbyKaoruIshikawa.“QC7tools”playedanimportantpartinJapanseconomicrecoveryanddevelopment.,QC7Tools-CheckSheet,Whatischecksheet?Atablewhichlistsoutallitemsneedchecking.Checksheetincludes,butnotlimitedto:diagnoses,questionnaire,record,statistics,etc.,CheckSheet-Keypoints,Keypoints:1.Verifytheitemstocheck;2.Verifythefrequencytocheck;3.Verifythepersonneltocheck.,Implementprocedure,1.Verifytheobject;2.Framethechecksheet;3.Checkandrecord;4.RequestaimprovementaimingattheNCitems5.Verifytheimprovement6.Summarizeperiodicallyandimprovepersistently.,LevelDiagram,Whatisleveldiagram?Sortallopinions,viewsorthoughtsbyspecifictopicandgroupthecollecteddataorinformation.,Implementprocedure,1.Identifythetopictostudy;2.Frametheleveldiagramandcollectdata;3.Sortthedatatovariouslevels;4.Analyzethedata.,QC7Tools-Histogram,Whatishistogram?Ahistogramisasimplefrequencydistribution.Itisaplotoftheactualdatashowingthedatavaluesversusthenumberofoccurrencesforeachvalue.,JudgetheProcessCapability(Cp)fromthehistogram,CpisjustOK,Cpisbetterthanspec,Cpisleantoleft,Cpisleantoright,TooscatteredCp,ImplementProcedure,1.Collectdata;Forexample:GeardimensionproducedbyABCfactoryasbelow;specificationofthisgearis24.56mm:,ImplementProcedure,2.Counttherange:R=XmaxXmin=30.0-17.4=12.63.Setthegroup:,Weset10groupsinthisexample.,Implementprocedure,4.Verifytheminmeasurementunit:Itisdecidedbydecimaldigits.Minimummeasurementunitinthisexampleis0.1.5.Counth;h=R/10=12.6/10=1.261.3,Implementprocedure,6.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:29.05-30.35,Implementprocedure,7.Countmedian;Groupmedian=(Groupupperlimit+Grouplowerlimit)/21stgroupmedian=(17.35+18.65)/2=18.00Therestmaybededucedbyanalogy.,Implementprocedure,8.Fillfrequencytable:,9.Drawhistogram.,Implementprocedure,10.Analyzethehistogram.Thishistogrambelongstonormaldistribution,sotheprocessisconsideredasstable.,QC7tools-ParetoDiagram,WhatisParetodiagram?Itisadiagrambasedonhistogramandusedtoidentifythe“criticalminor”.Paretodiagramcanbeusedtofindoutthemajorproblemonquality,cost,leadtime,safety(phenomenon);operator,machine,material,working(process).,Paretodiagramprocedure,Takethedefectsfoundinafigureproductionforexample,total15854products,including216defectives.1.Collectdata2.Sortorder(descending),andcountaccumulativepercentage.,Paretodiagramprocedure,3.DrawXaxisandYaxisandmarkingscale.4.Drawhistogram.5.Drawaccumulativecurve.6.AnalyzeParetodiagramandtakecorrectiveaction.(Veryimportant).,QC7tools-Cause-and-effectdiagram,WhatisCause-and-effectdiagram?Itisatooltoanalyzethequalitycharacteristics(effect)andthepotentialfactortoeffectthecharacteristics(cause).,Keypoints,1.PersonnelfromdifferentDept;2.Analyzethecauseasdetailaspossible;3.Eachqualitycharacteristicneedsacause-and-effectdiagram;4.Verifytheproblemcanbesolvedornot;ifnot,subdividethecause.,ImplementProcedure,1.3-6variousdeptrepresentativestoformagroup;2.Topic:forexample,whydoesdimensionofgearvary?3.Drawouttherib,setthemajorcause,Whydoesdimensionofgearvary?,Man,Machine,Material,Method,Environment,ImplementProcedure,4.Findoutthedetailcauseandaddtothediagram(“BrainStorm”isrecommended);5.Markthecausethatmaybetherootoftheproblemandtakecorrectiveaction.,Whydoesdimensionofgearvary?,Man,Machine,Method,Environment,Material,Wrongoperation,Notenoughtraining,Notimelychecking,Patrolintervaltoolong,Laxdiscipline,Insufficienthardness,Varioushardness,Differentsuppliers,Impurematerial,Equipmentprecision,Hardtoadjust,Instablevoltage,Poorfixture,Notimelymaintenance,Nooperationinstruction,Noise,Temperaturevaries,Insufficientlight,Analysis,Findout3majorproblems:1.Material:5differentsuppliers,notthesamequality,andnotstable;2.Person:Newworkers,notenoughtrainingresultsinwrongoperation;3.Method:NoWIorWIcontentnotrelatedtoactualwork.,QC7Tools-ScatterDiagram,Whatisscatterdiagram?AdiagramtofindoutwhetherthereisanyrelationshipbetweentwovariablesbyplottingthedatainX-Yaxlecoordinates.,Typesofscatterdiagram,Generallythereare4typesofscatterdiagram:Positivecorrelation(X,Y);Negativecorrelation(X,Y);Nocorrelation;Curvecorrelation.,Keypoint,1.Checkifthereisabnormaldot,findoutthecauseoftheabnormal;2.Datashouldbeenough(atleast30)3.Asdataisalwaysvaryingduetoman,machine,material,method,environment,etc,weshouldsortthedatatoavoideffect.(leveldiagram).,Implementprocedure,1.Verifythe2variablestocheckandcollectthedata(atleast30groups);2.MarkthedotontheX-Ycoordinates;3.Judgetherelationship.,Example,Scatterdiagramofmotorcontinuousoperationtime(T)andvelocity(V):Fig.4,QC7Tools-ControlChart,Whatiscontrolchart?Controlchartsareameansofgraphingvariationpatternsfromprocessorproductcharacteristicssothatcorrectiveactionmaybetakenifrequired.,Normaldistribution,Normaldistributionisacurveofwhichthecenterisprotruded,twosidesofthecurvearelowerandsymmetrical.Weusetwoparametertodescribethenormaldistribution;(Meanvalue)and(standarddeviation).,Parameterand,Thenormalcurvemovestorightwhenincreases.,=2.5,=1.0,=0.4,Qualitycharacteristicsbecomemorescatteredaccompaniedwiththeincreaseofthevalueof.,TheoreticbasistosetUCLandLCL,TheCentralline(CL)ofcontrolchartisthemeanvalue;UpperControlLimit(UCL)ismeanvalue+3andLowerControlLimitismeanvalue-3.,+3,+2,+1,-1,-2,-3,CL,UCL,LCL,Relationshipbetweenanddefectivepercentage,*Consideringinfluencesfromvariousfactors.*4.5represents1350ppmdefectives.Comparing6and3,defectivepercentagereduced20,000times!Motorolarequesthissupplierprovideproductswith6quality;,3and6,Whichkindofcontrolcharttochoose?,Variables,Attributes,1Unit,Defectives,Defects,Stable,Var