第八章供应链的综合计划.ppt

8,AggregatePlanninginaSupplyChain,LearningObjectives,Identifythedecisionsthatarebestsolvedbyaggregateplanning.Understandtheimportanceofaggregateplanningasasupplychainactivity.Describetheinformationneededtoproduceanaggregateplan.Explainthebasictrade-offstoconsiderwhencreatinganaggregateplan.FormulateandsolvebasicaggregateplanningproblemsusingMicrosoftExcel.,RoleofAggregatePlanninginaSupplyChain,CapacityhasacostandleadtimesareoftenlongAggregateplanning:processbywhichacompanydetermineslevelsofcapacity,production,subcontracting,inventory,stockouts,andpricingoveraspecifiedtimehorizongoalistomaximizeprofitdecisionsmadeataproductfamily(notSKU)leveltimeframeof3to18monthshowcanafirmbestusethefacilitiesithas?,RoleofAggregatePlanninginaSupplyChain,SpecifyoperationalparametersoverthetimehorizonProductionrateSubcontractingWorkforceBacklogOvertimeInventoryonhandMachinecapacitylevelAllsupplychainstagesshouldworktogetheronanaggregateplanthatwilloptimizesupplychainperformance,TheAggregatePlanningProblem,Giventhedemandforecastforeachperiodintheplanninghorizon,determinetheproductionlevel,inventorylevel,andthecapacitylevelforeachperiodthatmaximizesthefirms(supplychains)profitovertheplanninghorizonSpecifytheplanninghorizon(typically3-18months)SpecifythedurationofeachperiodSpecifykeyinformationrequiredtodevelopanaggregateplan,InformationNeededforanAggregatePlan,AggregatedemandforecastFtforeachPeriodtoverTperiodsProductioncostsLaborcosts,regulartime($/hr)andovertime($/hr)Subcontractingcosts($/hror$/unit)Costofchangingcapacityhiringorlayoff($/worker),addingorreducingmachinecapacity($/machine)Labor/machinehoursrequiredperunitInventoryholdingcost($/unit/period)Stockoutorbacklogcost($/unit/period)Constraintsovertime,layoffs,capitalavailable,stockouts,backlogs,fromsuppliers,OutputsofAggregatePlan,Productionquantityfromregulartime,overtime,andsubcontractedtimeInventoryheldBacklog/stockoutquantityMachinecapacityincrease/decreaseApooraggregateplancanresultinlostsales,lostprofits,excessinventory,orexcesscapacity,IdentifyingAggregateUnitsofProduction,AggregateunitshouldbeidentifiedinawaythattheresultingproductionschedulecanbeaccomplishedinpracticeFocusonthebottleneckswhenselectingtheaggregateunitandidentifyingcapacityandproductiontimesAccountforactivitiessuchassetupsandmaintenance,RedTomatoTools,Table8-1,RedTomatoTools,WeightedaverageapproachMaterialcostperaggregateunit=15x0.10+7x0.25+9x0.20+12x0.10+9x0.20+13x0.15=$10SimilarlyRevenueperaggregateunit=$40Netproductiontimeperaggregateunit=4.00hours,AggregatePlanningStrategies,Trade-offbetweencapacity,inventory,backlog/lostsalesChasestrategyusingcapacityastheleverTimeflexibilityfromworkforceorcapacitystrategyusingutilizationastheleverLevelstrategyusinginventoryastheleverTailoredorhybridstrategyacombinationofstrategies,ChaseStrategy,VarymachinecapacityorhireandlayoffworkersasdemandvariesOftendifficulttovarycapacityandworkforceonshortnoticeExpensiveifcostofvaryingcapacityishighNegativeeffectonworkforcemoraleResultsinlowlevelsofinventoryUsedwheninventoryholdingcostsarehighandcostsofchangingcapacityarelow,TimeFlexibilityStrategy,UseexcessmachinecapacityWorkforcestable,numberofhoursworkedvariesUseovertimeoraflexibleworkscheduleFlexibleworkforce,avoidsmoraleproblemsLowlevelsofinventory,lowerutilizationUsedwheninventoryholdingcostsarehighandcapacityisrelativelyinexpensive,LevelStrategy,Stablemachinecapacityandworkforcelevels,constantoutputrateInventorylevelsfluctuateovertimeInventoriescarriedoverfromhightolowdemandperiodsBetterforworkermoraleLargeinventoriesandbacklogsmayaccumulateUsedwheninventoryholdingandbacklogcostsarerelativelylow,AggregatePlanningUsingLinearProgramming,RedTomatoToolsHighlyseasonaldemandDevelopaforecast,Table8-2,RedTomatoTools,Table8-3,RedTomatoToolsDecisionVariables,Fort=1,.,6Wt=WorkforcesizeformonthtHt=NumberofemployeeshiredatthebeginningofmonthtLt=NumberofemployeeslaidoffatthebeginningofmonthtPt=ProductioninmonthtIt=InventoryattheendofmonthtSt=NumberofunitsstockedoutattheendofmonthtCt=NumberofunitssubcontractedformonthtOt=Numberofovertimehoursworkedinmontht,RedTomatoToolsObjectiveFunction,Minimize(Regular-timelaborcost+Overtimelaborcost+Costofhiringandlayoffs+Costofholdinginventory+Costofstockingout+Costofsubcontracting+Materialcost),RedTomatoToolsConstraints,Workforce,hiring,andlayoffconstraints,Allfort=1,.,6,Capacityconstraints,Inventorybalanceconstraints,Overtimelimitconstraints,RedTomatoTools,RedTomatoTools,Totalcostoverplanninghorizon=$422,275Revenueoverplanninghorizon=40 x16,000=$640,000,Table8-4,RedTomatoTools,Averageseasonalinventory,RedTomatoTools,Higherdemandvariability,Table8-5,Averageseasonalinventory,RedTomatoTools,Totalcostoverplanninghorizon=$432,858,Table8-6,RedTomatoTools,Lowerhiringandlayoffcosts,Averageseasonalinventory,Totalcostoverplanninghorizon=$412,688,RedTomatoTools,Table8-7,ForecastErrorinAggregatePlans,ForecasterrorsmustbeconsideredSafetyinventorySafetycapacityUseovertimeasaformofsafetycapacityCarryextraworkforcepermanentlyasaformofsafetycapacityUsesubcontractorsasaformofsafetycapacityBuildandcarryextrainventoriesasaformofsafetyinventoryPurchasecapacityorproductfromanopenorspotmarketasaformofsafetycapacity,AggregatePlanningInExcel,Fort=1,.,6Wt=WorkforcesizeforMonthtHt=NumberofemployeeshiredatthebeginningofMonthtLt=NumberofemployeeslaidoffatthebeginningofMonthtPt=ProductioninMonthtIt=InventoryattheendofMonthtSt=NumberofunitsstockedoutattheendofMonthtCt=NumberofunitssubcontractedforMonthtOt=NumberofovertimehoursworkedinMontht,AggregatePlanningInExcel,Figure8-1,AggregatePlanningInExcel,Figure8-2,AggregatePlanningInExcel,Figure8-3,AggregatePlanningInExcel,Figure8-4,BuildingaRoughMasterProductionSchedule,Disaggregateanaggregateplan,Table8-8,TheRoleofITinAggregatePlanning,TheabilitytohandlelargeproblemsTheabilitytohandlecomplexproblems(througheithernonlinearoptimizationorlinearapproximations)TheabilitytointeractwithothercoreITsystemssuchasinventorymanagementandsourcing,ImplementingAggregatePlanninginPractice,ThinkbeyondtheenterprisetotheentiresupplychainMakeplansflexiblebecauseforecastsarealwaysinacc