约束理论---TOC

BeltonConfidential1TowardsOperationalExcellenceLEANPractitionerProgramTheoryofConstraint約束理論BeltonConfidential2VisualManagement目視管理ValueStreamMapping价值流程圖MaterialControl物料控制TPM全面生產性維護LayoutOptimization/Cell布局優化／CellSMED/QuickChangeover快速切換ErrorProofing防錯法PerformanceMetrics績效指標TheoryOfConstraints約束理論LeanDiagnostic精益診斷ChangeM&WasteE改變觀念&消除浪費LeanOverview精益概述LeanTools精益工具TherearemanytoolsandtechniquesintheLean‘toolbox’,allsuitedtodifferentapplicationsandcircumstances.在LEAN工具箱中有許多工具和技巧,它們可以用于各種不同的情況.BeltonConfidential3Objective課程目的•UnderstandbasicconceptsofTheoryofConstraint理解約束理論的基本概念•PresentandexploretheTOCfivefocusingsteps介紹和探究TOC的五個步驟•HowtheDrumBufferRopeprincipleworksDBR原則如何運作•Gamestudy游戲練習BeltonConfidential4OrganizationalGoals組織目標Profitabilityandmarketshareforthecompany利潤和市場份額QualityInventorySalesCostMaximizeReturnonInvestmentROI投資回報率BeltonConfidential5TOC-Assumptions設想•Thereisafundamentalgoalforeveryorganization.每個組織有一個基本的目標.•Everyorganizationisconstrainedinsomeway(eitherinternalorexternal).每個組織都被某些因素限制著(不管是內部還是外部).•Whiletherearemanycausallinkages,therearefewcorecausesthatlimitachievementoforganizationalgoal.當存在許多因果關系時﹐總有一些關鍵的原因約束著組織達成目標.BeltonConfidential6•ROImeasuresorganizationalor“system”performance(wherethethe“system”isachainofdependentevents),thereforethekeymanagementdilemmaissimplyROI衡量了一個組織或系統的績效(這里的系統是指相互依賴的一個鏈),所以關鍵的管理兩難是:DOWEMANAGETHESYSTEM?我們管理這個系統OR還是DOWEMANAGETHECHAINOFEVENTSASINDEPENDENTSYSTEMS?把這一系列的事件當作獨立的系統來管理?ManagementDilemma管理兩難BeltonConfidential7TOCPhilosophyTOC哲學TheoryofConstraints(TOC)isasystem-basedphilosophywhichassertsthattheconstraint(Bottleneck)determinestheperformanceofthesystem.TOC是以系統為基礎的哲學,它聲稱瓶頸決定整個系統的績效.Managingfromthekeyleveragepointsprovidesthefocustomaximizethesystem.在杠杆點進行管理可以聚焦于最大化系統的績效.ThetheoryofConstraintsapproachesimprovementatthesystemlevel,ratherthanindividualprocessesorisolatedelementsothesystem約束理論方法在于改善系統,而不是單個工序或系統中被隔离的要素BeltonConfidential8TheTheoryofConstraints瓶頸理論TOCwasdevelopedbyDr.EliyahuM.Goldratt,aPhysicist.約束理論又稱瓶頸理論,是由物理學家-高德拉特博士提出和發展而來.TOCsuggeststhat:TOC提出:•Allsystemssimilartochains.所有的系統如同一條鏈.•Eachchainiscomposedoflinkswhichvaryinstrengthandcapability.每一條鏈都是由各种多樣化力量和能力的聯接點組成.•Inanyindependentchainthereisonelink-andonlyone-thatisweakerthanalltherest:theweakestlink.在任何獨立的鏈里都存在一個聯接-且只有一個-比其它弱:最弱的聯接點.•Theweakestlinkistheconstrainttothesystem’sperformance.最弱的聯接點就是影響系統績效的約束點.BeltonConfidential9兩种約束•Physical物理方面:People+Materials+Machine+Geography地理•Non-Physical非物理方面:Policies+Rules+Measurements+Training瓶頸是整個系統中最無力的環節,約束著組織達成目標(有效產出﹑品質﹑交期﹑成本等）BeltonConfidential10TOC5大步驟1.IdentifytheConstraint找出系統的瓶頸2.Decidehowtooptimizetheconstraint決定如何挖盡瓶頸的潛能3.Subordinateotheroperations其他的一切配合上述決定4.Elevatetheconstraint把瓶頸松綁5.Gobacktostep回到第一步BeltonConfidential11TOCObjective目的Toimprovethestrengthofthesystemweneedtofindtheweakestlinkinthechainandstrengthenit.要提高系統的力量﹐我們必須從系統鏈中找出最無力的環節並強化它.BeltonConfidential12ProductionManagementusingTheoryofConstraintsDrum鼓-Buffer緩沖器–Rope(DBR)BeltonConfidential13DrumBufferRope(DBR)-定義•Drum鼓:瓶頸(最慢工序)的速度或產能•DrumBeat鼓點:瓶頸的進度;用來優化瓶頸效率•Buffer緩沖器:放在瓶頸前的以時間為基礎的存貨•BufferManagement緩沖器管理:目的是有一個合适的庫存防止瓶頸斷料﹐同時使周期最小化﹐瓶頸的進度最優化•Rope繩子:原材料發放机制IntheDBRprocess,everyeffortismadetoincreasetheefficiencyoftheconstraintevenatthedetermentofothermeasures.Theinventorylevel(thebuffer)mustensuretheconstraintneverrunsoutofwork.Theropemechanismrestrictsallinventorynotneededtoprotecttheconstraintfromenteringthesystem.Eachoperationisdirectedtoworkasfastaspossible(withoutcompromisingquality)whenthereisworkandtositidleifthereisnotwork.BeltonConfidential14Drum-Buffer-RopeThesloweststep/activityinthemanufacturingchainsetsthe“DrumBeat”在制造鏈中最慢的工序設置一個鼓點CapacityConstrainedResource(CCR)ABCD400250350425BeltonConfidential15Drum-Buffer-RopeA“buffer”isplacedin-frontofthesloweststepintheprocesstoprotecttheconstraint一個緩沖器放在最慢的工序前來保護瓶頸ABCDBufferBeltonConfidential16WhatdoBuffersdo緩沖器有什么用?•Provideatimebased(bufferupperiodically)reserveofmaterialtoprotecttheConstraint(andtheentireprocess)fromlostoperatingtimeduetovariationsin准備一個以時間為基礎的物料儲備來防止瓶頸損失加工時間﹐這是由于變異來自:•set-uptimes切換時間•processingtimes加工時間•machinebreakdowns機器故障•traveltime運輸時間•delays延期•normalprocessstatisticalfluctuations正常工序統計波動•Provideanopportunitytooptimizeconstraintschedule提供優化瓶頸的机會–eg.ganginglikeproductsincreasesrunlengthandincreasesconstraintuptimeandoverallplantoutput增加瓶頸的運行時間﹐增加瓶頸的開机時間和總產出.•Tietothegatingoperationtocontrolthereleaseofrawmaterialintotheprocessstream按照瓶頸工序的需求來發放原材料到生產線BeltonConfidential17BufferManagement緩沖器管理3210EverythingisOK(stopupstreamproduction)Watch&planhowyouwouldexpediteACT!weareintrouble!Theprofileofthebuffergovernswhattypeofexpeditingwearerequiredtodo(nothing,plantoexpedite,expedite)Buffersizeisatrade-offbetweenprotectionandleadtimeifbuffersizeisincreased,protectionincreases,howeversodoesmanufacturingleadtimeThebuffercanbeproperlysizedbymonitoringthe“holes”“Holes”telluswheretomakeournextprocessimprovementandwheretheconstraintwillmovewhenthecurrentconstraintiselevatedBecomestheprincipleshopfloorcontrol