第八章 供应链的综合计划PPT幻灯片课件.pptx

8 AggregatePlanninginaSupplyChain LearningObjectives Identifythedecisionsthatarebestsolvedbyaggregateplanning Understandtheimportanceofaggregateplanningasasupplychainactivity Describetheinformationneededtoproduceanaggregateplan Explainthebasictrade offstoconsiderwhencreatinganaggregateplan FormulateandsolvebasicaggregateplanningproblemsusingMicrosoftExcel RoleofAggregatePlanninginaSupplyChain CapacityhasacostandleadtimesareoftenlongAggregateplanning processbywhichacompanydetermineslevelsofcapacity production subcontracting inventory stockouts andpricingoveraspecifiedtimehorizongoalistomaximizeprofitdecisionsmadeataproductfamily notSKU leveltimeframeof3to18monthshowcanafirmbestusethefacilitiesithas RoleofAggregatePlanninginaSupplyChain SpecifyoperationalparametersoverthetimehorizonProductionrate SubcontractingWorkforce BacklogOvertime InventoryonhandMachinecapacitylevelAllsupplychainstagesshouldworktogetheronanaggregateplanthatwilloptimizesupplychainperformance TheAggregatePlanningProblem Giventhedemandforecastforeachperiodintheplanninghorizon determinetheproductionlevel inventorylevel andthecapacitylevelforeachperiodthatmaximizesthefirm s supplychain s profitovertheplanninghorizonSpecifytheplanninghorizon typically3 18months SpecifythedurationofeachperiodSpecifykeyinformationrequiredtodevelopanaggregateplan InformationNeededforanAggregatePlan AggregatedemandforecastFtforeachPeriodtoverTperiodsProductioncostsLaborcosts regulartime hr andovertime hr Subcontractingcosts hror unit Costofchangingcapacity hiringorlayoff worker addingorreducingmachinecapacity machine Labor machinehoursrequiredperunitInventoryholdingcost unit period Stockoutorbacklogcost unit period Constraints overtime 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 lostsalesChasestrategy usingcapacityastheleverTimeflexibilityfromworkforceorcapacitystrategy usingutilizationastheleverLevelstrategy usinginventoryastheleverTailoredorhybridstrategy acombinationofstrategies 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 Averagetimeininventory 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 ThinkbeyondtheenterprisetotheentiresupplychainMakeplansflexiblebecauseforecastsarealwaysina