Lean Machines.docx

Lean Machines.docx

《Lean Machines.docx》由会员分享，可在线阅读，更多相关《Lean Machines.docx（14页珍藏版）》请在冰豆网上搜索。

LeanMachines

LeanMachines

Imagineaboardgameformanufacturingengineerswhereallthegamepiecesareassemblymachines,conveyors,partsfeeders,robotsandothertypesofequipment.ThegametakesplaceinaTier2autopartsplantthathasadoptedleanproductionprinciples.Theobjectiveistoacquiretherighttypeofassemblyequipmentwhileconfrontingmanagement,operatorsandcustomersconstantlychantingtheleanmanufacturingmantraof"wasteelimination."

Asleaninitiativesbecomemorepopular,manyengineersareplayingthatgameeveryday.Tothriveinthattypeofenvironment,engineersmustbreaktheage-oldhabitofalwayswantingtobuythefastestmachineequippedwiththelatestbellsandwhistles.Thetrickistochallengecomplexityandbalancetherightamountofautomationtomeetleanobjectivesandcustomerneeds.

Leanmanufacturinghasbeentoutedasthepanaceafortheproductionworld.However,theideaofcapitalequipmentexpenditureinaleansystemisviewedasanoxymoronbysomeobservers.Theyquestiontheroleofautomationinanenvironmenttheyperceivetobethedomainofmanualassemblyprocesses.

Othersmisinterpretleanandforegoquantumimprovementsinproductivitybymakingduewithexistingmachinesratherthanpurchasingadditionalautomationsystems.Theyfeelthatleanmanufacturingmeansspendinglessoncapitalequipment.

"Wehavecomeacrossmanycompaniesthatwishtoshortcutthecriticaladditionofequipment,"saysRichardLigus,presidentofRockfordConsultingGroup（Rockford,IL）."Atypicaltacticistopurchaseschedulingsoftwarebasedontheoryofconstraints.But,capitalequipmentplaysanextremelyimportantroleinthesuccessofaleanmanufacturingimplementation.Ihaven’tseenaprojectwhereequipmentwasn’tneeded."

Whenhisteamofconsultantsarriveatanewassignment,Ligussaysoneofthefirstthingstheycheckistheage,technologygenerationandconditionofcapitalequipment."Wealmostalwaysfindunbalancedcapacityandunderperformingequipment,"notesLigus,whosaysmanufacturingengineershaveatendencytooverautomate.

"Peopleseemtothinkleanmeansnotspendinganymoneyonautomatedequipment,"addsChetMarchwinski,communicationsdirectoroftheLeanEnterpriseInstitute（Brookline,MA）."Actually,youhavetohavesome—attherightlevelofautomation—oryoucan’timplementlean."

However,itisoftenmoredifficulttojustifycapitalequipmentexpenditureinaleanenvironment."Traditionally,capitalequipmentjustificationisbasedonprojectedutilizationrates,andthisthinkingisdeeplyingrained,notonlyinthemindsofaccountants,butinthemindsofengineersandmanagersaswell,"saysDonPenkala,presidentofGraniteBayConsultingInc.（GraniteBay,CA）.

"Inaleanenvironment,wasteeliminationandleadtimereductionarethekeygoals.Thesetwomeasuresaremorecustomer-focusedanddonotrequireassetutilizationratesthatleadtoexpensiveoverproduction,backlogsateachstageofmanufactureandneedlessstorageandmaterialhandlingcosts."

Leanprinciplesallowmanufacturerstosignificantlyboostthroughput,reducetimetomarketandquicklyincreasecapacity.Implementingaleanphilosophyalsohasthepotentialtolowercostsandimproveproductquality.

Manufacturersthathaveadaptedleanprincipleshaveachievedsomedramaticresults,suchasreducedfloorspaceandimprovedefficiency.Forinstance,DelphiAutomotiveSystems（Troy,MI）cut42feetoutoftheassemblylineatitsairconditioningcompressorplantinJaguariuna,Brazil.Thatminimizedthewalkpathofoperatorsbymorethan40percent.

TheMarvairdivisionofAirxcelInc.（Cordele,GA）recentlyreducedthespacerequiredtoassembleitscommercialairconditionersandheatpumpsfrom12,000squarefeetto6,000squarefeet,a50percentreduction.Atthesametime,itreducedhours-per-unitfrom9.28to5.19fora44percentimprovement.

LeanDefined

LeanmanufacturingtracesitsrootstoToyotaMotorCo.（Tokyo）.TheJapaneseautomakerdevelopeditsfamousToyotaProductionSystemmorethan50yearsago.Today,hundredsofcompanieshaveadapteditwithvaryingdegreesofsuccess.

RickHarris,presidentofHarrisLeanSystemsInc.（StampingGround,KY）,says30percentto40percentofallmanufacturersintheUnitedStatesclaimtobeimplementingleanprinciples."However,only5percentaretrulyimplementingleanmanufacturing,"claimsHarris,whoformerlyservedasmanageroffinalvehicleassemblyatToyotaMotorManufacturingInc.（Georgetown,KY）.

Leanmanufacturingismostcommonintheautoindustry,butcompaniesinotherindustriesrangingfromelectronicstofurniture,havesuccessfullymodifieditsbasicprinciples."Therearepocketsofcompaniesineveryindustrythataredoingitbest,"Harrispointsout.

Nomatterwhattypeofproductisbeingassembled,continuousimprovement,customerfocus,one-pieceflowandwastereductionplayakeyroleinleanmanufacturing.Thegoalistoeliminatenonvalue-addedactivitiesthatpreventaone-pieceflowofproduct.

"Leanthinkingfocusesonvalue-addedflowandtheefficiencyoftheoverallsystem,"saysDr.JeffreyLiker,directoroftheLeanProgramOfficeandtheJapanTechnologyManagementProgramattheUniversityofMichigan（AnnArbor,MI）."Leanmanufacturingisamanufacturingphilosophythatshortensthetimebetweenthecustomerorderandtheproductbuildandshipmentbyeliminatingsourcesofwaste."

Nomatterhowit’sdefined,leanisaconceptthatattackswastewithinaplantorcompany.Inaleanmethodology,wasteeliminationresultsincostreduction."Wasteisanythingthatdoesnotcontributetotransformingaparttoyourcustomer’sneeds,"saysLiker."TheNo.1causeofwasteisthefailuretorecognizethatitisthere."

Thereareseventypesofmanufacturingwaste:

productionoverimmediatedemand;excessworkinprocessandfinishedgoodsinventories;scrap,repairsandrejects;unnecessarymotion;excessiveprocessing;waittime;andunnecessarytransportation.

"Leanproductionisaimedattheeliminationofwasteineveryareaofproduction,includingcustomerrelations,productdesign,suppliernetworksandfactorymanagement,"saysDr.DavidCochran,directoroftheProductionSystemDesignLaboratoryatMassachusettsInstituteofTechnology（MIT,Cambridge,MA）."Itsgoalistoincorporatelesshumaneffort,lessinventory,lesstimetodevelopproductsandlessspacetobecomehighlyresponsivetocustomerdemandwhileproducingtopqualityproductsinthemostefficientandeconomicalmannerpossible."

AccordingtoGraniteBayConsulting’sPenkala,capitalequipmentexpenditureinaleanenvironmentshouldbejustifiedbasedontwofactors:

theamountofmanufacturingwasteeliminatedandthereductioninproductionleadArial."Wasteelimination,whichincludesproductqualityimprovement,andleadtimereductionarethemostimportantfactorstoconsider,"saysPenkala."Productivityimprovementsandlaborcostreductionareinternalmeasuresandtheleastimportant."

TimeFactors

Besideseliminatingwaste,leanproductioninitiativesfocusonreducingleadtime,whichisthetotaltimeacustomermustwaittoreceiveaproductafterplacinganorder.Takttimeformstheheartbeatofanyleansystem.Itsetsthepaceofproductiontomatchtherateofcustomerdemand.

Takttimeisdeterminedbydividingtheavailableproductiontimebytherateofcustomerdemand.Forexample,ifanautomotiveOEMdemands320fuelpumpsperdayandaTier2partsplantoperatestwoshiftsadayforatotalof960minutes,thetakttimeis3minutes.

"Ideally,inaleanenvironment,equipmentwilloperateataratedeterminedbyforecastedcustomerdemand,"saysPenkala."Thisiscontrarytojustificationbasedonhighutilizationrates.Customerdemand,includingtakttime,rapidresponse（delivery）andqualityimprovementshouldplayamajorroleincapitalequipmentjustification."

Leanexpertsclaimitiseasiertomeetcustomerdemandwithsimpler,dedicatedpiecesofequipment."Complexequipmentmaynotbetheanswer,"warnsRickHarris."It’sbettertolookforalowcapitalpieceofequipmentthatwillmakewhatyourcustomerwants,withtheabilitytoproducemoreifthecustomerdemands.Thelowerthecomplexity,thebetteroffyouwillbeinthelongrun.Unfortunately,manymachinebuildersareinbusinesstomakecomplexmachines.ToomanypeoplewanttosellaCadillacwhenaChevywilldo."

AccordingtoHarris,coauthorofCreatingContinuousFlow（publishedbytheLeanEnterpriseInstitute）,machinetimeshouldbecloselycalibratedtotakttime."Inaworldwheremachinesarenotcompletelycapableoravailableanddemanddoeschange,itisbesttotargeteffectivecycleArialforeverymachineinthecellatnomorethan80percentofthefastest—highestvolume—takttime,"heexplains."Thisensuresthatoperatorswillnothavetowaitformachinestofinishcyclingthenexttimetheycomearoundtogothroughtheworkelements.Italsoprovidesabitofextracapacitytoaccommodatesomedemandincreaseswithouttheneedtoaddcapitalequipmentorpaylargeamountsofovertime."

Harrisandotherleanexpertspointoutthatengineershaveatendencytobuymorecapacitythanisneeded.JohnShook,aDexter,MI-basedsenioradvisortotheLeanEnterpriseInstitute,saysmanufacturingengineersshouldconsidermarketsizeanddemandprojectionswhenbuyingnewequipment.

"Lookforsmallerincrementsofcapacity,"suggestsShook,whoformerlyservedasdeputygeneralmanagerofToyota’sSupplierSupportCenter."Sooften,demandforecaststendtobewrong.Wejustdon’tknowwhatdemandisgoingtobe."

Thepaceofproductionshouldbe