Mistake Proofing-Poka yoke

1MistakeProofing(PokaYoke)Techniquesthatmakeitimpossibletomakemistakes2Tableofcontents1)Returnsproducebymistakeproofingpage32)Whatismistakeproofingpages4-73)MistakeproofingversusStatisticalProcessControlpages84)Anewattitudetowardpreventingerrorspages9-155)Overviewofthedifferentinspectiontechniquespages16-206)Theultimategoal:achievingzerodefectspages21-237)TypesofPokayokecontrolsystemspages24-268)TypesofPokayokedevicespages27-309)Typesofsensorsusedpages31-3410)Guidelinesandrulespages35-3631)Returnsproducebymistakeproofing?Mistakeproofing(PokaYoke)willallowyoutodecrease:humanerrors,defectiveproductsatcustomers’,nonqualitycostsMistakeproofing(PokaYoke)willallowyoutoincreasealso:productivity,profitsAfewexamples:Danacorporationhasreporteda$500,000savingsresultingfroma$6deviceOrtho-ClinicalDiagnostics(Johnson&Johnson)saved$75000annuallybyimplementinganewPokayokeAT&TPowerSystems(LucentTechnologies)reportednetsavingof$2545perdevice(3300devices)Section1234567891042)Whatismistakeproofing?Theuseofprocessordesignfeaturestopreventerrorsortheirnegativeimpact.AlsoknownasPokayoke,Japaneseslangfor“avoidinginadvertenterrors”whichwasformalizedbyShigeoShingo(Toyota).Inexpensive.Veryeffective.Basedonsimplicityandingenuity.APokayokedeviceisanymechanismthateitherpreventsamistakefrombeingmadeormakesthemistakesobviousataglanceSection123456789105EverydayExamplesWhichdialturnsontheburner?StoveA-difficulttoswitchonStoveB-simple,visuallytoswitchonSection123456789106OthereverydayExamplesNewlawnmowersarerequiredtohaveasafetybaronthehandlethatmustbepulledbackinordertostarttheengine.Ifyouletgoofthesafetybar,themowerbladestopsin3secondsorless.Fuelingareaofcarhasthreeerror-proofingdevices:1.insertkeepsleaded-fuelnozzlefrombeinginserted2.tetherdoesnotallowlossofgascap3.gascaphasratchettosignalpropertightnessandpreventovertightening.Section123456789107CostofPokayokedevices…About50%ofPokayokedevicescostlessthan$100About90%ofPokayokedevicescostlessthan$1,000MakingprocessesbetterthankstoPokayokeleadstoreduced:ReworkScrapWarrantycostsInspectioncosts...versuscostofdefectsSection1234567891083)MistakeproofingvsSatisticalProcessControl(SPC)StatisticalProcessControl(SPC)isgoodatdetectingshiftsintheprocessmeanorvariance.Changestotheprocessmustbeongoingtobereadilydetected.Humanerrorstendtoberare,intermittentevents.Theyarenotreadilydetectedbycontrolcharts.Usemistakeproofing(notSPC)toreducedefectscausedbyhumanerrorSection1234567891094)AnewattitudetowardpreventingmistakesImpementingcorrectiveactions:amajorityofcompaniesreportthatatleast20-30%ofcorrectiveactionsare:“workerreprimandedandretrained.”acorrectiveactionisanactionaimedateradicatingaqualityproblempermanentlybyeliminatingtherootcause(s).Theadmonitionto“bemorecareful”or“payattention”arenoteffectiveforhumans,especiallyinrepetitiveenvironments.Section1234567891010CausesofdefectsPoorproceduresorstandardsMachinesNon-conformingmaterialWorntoolingHumanMistakesExceptforhumanmistakestheseconditionscanbepredictedandcorrectiveactioncanbeimplementedtoeliminatethecauseofdefectsSection1234567891011“Bemorecareful”noteffective“Theoldwayofdealingwithhumanerrorwastoscoldpeople,retrainthem,andtellthemtobemorecareful…Butyoucan’tdomuchtochangehumannature,andpeoplearegoingtomakemistakes.Ifyoucan’ttoleratethem...youshouldremovetheopportunitiesforerror.”“Trainingandmotivationworkbestwhenthephysicalpartofthesystemiswell-designed.Ifyoutrainpeopletousepoorlydesignedsystems,they’llbeOKforawhile.Eventually,they’llgobacktowhatthey’reusedtoorwhat’seasy,insteadofwhat’ssafe.”Chappell,L.1996.ThePokayokeSolution.AutomotiveNewsInsights,(August5):24i.LaBar,G.1996.CanErgonomicsCure‘HumanError’?OccupationalHazards58(4):48-51.“You’renotgoingtobecomeworldclassthroughjusttraining,youhavetoimprovethesystemsothattheeasywaytodoajobisalsothesafe,rightway.Thepotentialforhumanerrorcanbedramaticallyreduced.”Section1234567891012Anewattitudetowardpreventingmistakes(1/4)MakeiteasiertodiscovertheerrorsthatoccurSection1234567891013Anewattitudetowardpreventingmistakes(2/4)Makeitpossibletoreverseactions—to“undo”them—ormakeithardertodowhatcannotbereversedSection1234567891014Anewattitudetowardpreventingmistakes(3/4)MakewrongactionsmoredifficultSection1234567891015Anewattitudetowardpreventingmistakes(4/4)Makeincorrectactionscorrect.Section12345678910165)OverviewofthedifferentinspectiontechniquesThe3basicapproachestoinspectionofprocessedproductsare:Judgement/StandardInspectionInformativeInspectionSourceInspectionThefirsttwoapproachesarewidelyusedandconsideredtraditionalOnlySourceInspectionactuallyeliminatesdefectsSection1234567891017InspectiontechniquesInspectionTechniquesDescription1)JudgementAssessesqualityofproductionoutputsorsortsoutdefectsfromgoodproduct.2)InformativeAssessesprocessbyinspectingoutputsandusinginformationgainedtocontroltheprocess(afeedbackloop).3)SourceAssessesbeforehandwhethertheconditionnecessaryforhighqualityproductionexist.Section1234567891018JudgementInspectionInvolvessortingthedefectsout