七章供應(yīng)鏈綜合計(jì)劃

Chapter7

AggregatePlanning

intheSupplyChain8-1LearningObjectivesIdentifythedecisionsthatarebestsolvedbyaggregateplanningUnderstandtheimportantofaggregateplanningasasupplychainactivityDescribetheinformationneededtoproduceanaggregateplanExplainthebasictrade-offstoconsiderwhencreatinganaggregateplanFormulateandsolvebasicaggregateplanningproblemusingMicrosoftExcel2OutlineRoleofaggregateplanninginasupplychainTheaggregateplanningproblemAggregateplanningstrategies(三種策略略)AggregateplanningusinglinearprogrammingImplementinglinearprogrammingforaggregateplanningusingMicrosoftExcelImplementingaggregateplanninginpractice3RoleofAggregatePlanninginaSupplyChainCapacityhasacost,leadtimesaregreaterthanzeroQuestionShouldacompanyinvestinaplantwithlargecapacitythatisabletoproduceenoughtosatisfydemandeveninthebusiestmonth??Shouldacompanybuildasmallerplantbutincurthecostsofholdinginventorybuiltduringslowperiodinanticipationofdemandinlatermonths?Thesearetypesofquestionsthataggregateplanninghelpscompaniesanswer4RoleofAggregatePlanninginaSupplyChainAggregateplanning((總體計(jì)劃劃):processbywhichacompanydeterminesideallevelsofcapacity,production,subcontracting,,inventory,stockouts,andpricingoveraspecifiedtimehorizonThegoalistosatisfydemandwhilemaximizeprofit供應(yīng)鏈綜綜合計(jì)劃劃之上，，是供應(yīng)應(yīng)鏈戰(zhàn)略略；供應(yīng)鏈綜綜合計(jì)劃劃之下，，是企業(yè)業(yè)資源計(jì)計(jì)劃；綜合計(jì)劃劃介于之之間。對對上細(xì)化化，對下下驅(qū)動(dòng)內(nèi)內(nèi)部供應(yīng)應(yīng)鏈，驅(qū)驅(qū)動(dòng)“企企業(yè)資源源計(jì)劃””。5RoleofAggregatePlanninginaSupplyChainAggregateplanningisanimportantsupplychainissueTobeeffective,,itrequiresinputsfromthroughoutthesupplychain,anditsresultshaveatremendousimpactsonsupplychainperformance.CollaborativeforecastsarecreatedbymultiplesupplychainenterprisesandareanimportantinputforaggregateplanningManyconstraintsinaggregateplanningcomefromsupplychainpartnersoutsidetheenterpriseTheoutputfromaggregateplanningisalsoofvaluetobothupstreamanddownstreampartners6RoleofAggregatePlanninginaSupplyChainThemainobjectiveofaggregateplanneristoidentifythefollowingoperationalparametersoverthespecifiedtimehorizon::Productionrate((生產(chǎn)率):thenumberofunitstobecompletedperunittime(suchasperweekorpermonth)Workforce((勞動(dòng)力數(shù)數(shù)量):thenumberoftheworkers/unitsofcapacityneededforproduction.Overtime((加班量):theamountofovertimeproductionplanned.Machinecapacitylevel(機(jī)器生產(chǎn)產(chǎn)能力):thenumberofunitsofmachinecapacityneededforproduction.7RoleofAggregatePlanninginaSupplyChainSubcontracting((轉(zhuǎn)包合同同):thesubcontractedcapacityrequiredovertheplanninghorizon.Backlog:demandnotsatisfiedintheperiodinwhichitarisesbutcarriedovertofutureperiod..Inventoryonhand((現(xiàn)有庫存存):theplannedinventorycarriedoverthevariousperiodsovertofutureperiods.Allsupplychainstagesshouldworktogetheronanaggregateplanthatwilloptimizesupplychainperformance8TheAggregatePlanningProblemGiventhedemandforecastforeachperiodintheplanninghorizon((計(jì)劃期),determinetheproductionlevel((生產(chǎn)水平平),inventorylevel((庫存水平平),andthecapacitylevel(生產(chǎn)能力力水平)foreachperiodthatmaximizesthefirm’’s((supplychain’s))profitovertheplanninghorizonSpecifytheplanninghorizon(typically3-18months))Specifythedurationofeachperiod9InformationNeededforinAggregatePlanDemandforecastineachperiodProductioncosts(生產(chǎn)成本本)laborcosts,regulartime($$/hr)andovertime(($//hr))subcontractingcosts(($/hror$$/unit))costofchangingcapacity:hiringorlayoff($$/worker)andcostofaddingorreducingmachinecapacity(($//machine)Labor/machinehoursrequiredperunitInventoryholdingcost(庫存成本本)($$/unit//period)Stockoutorbacklogcost((庫存缺貨貨或積壓壓成本））($/unit/period)Constraints:limitsonovertime,layoffs,capitalavailable,stockoutsandbacklogs..Constraintsfromsupplierstotheenterprise10OutputsofAggregatePlanProductionquantityfromregulartime,overtime,andsubcontractedtime；Inventoryheld；Backlog/stockoutquantity；WorkforceHired//Laidoff；Machinecapacityincrease/decrease；Apooraggregateplancanresultinlostsales,lostprofits,,excessinventory,,orexcesscapacity11FundamentalTradeoffsinAggregatePlanningCapacity((regulartime,overtime,subcontract))InventoryBacklog/lostsalesBasicStrategies（三種基基本策略略）ChasestrategyTimeflexibilityfromworkforceorcapacityLevelstrategy12AggregatePlanningStrategiesThesestrategiesinvolvetrade--offsamongcapitalinvestment,,workforcesize,workhours,inventory,,andbacklogs/lostsalesChasestrategy((追逐戰(zhàn)略略）–usingcapacityastheleverTimeflexibility（彈性時(shí)間間）fromworkforceorcapacitystrategy–usingutilizationastheleverLevelstrategy((水平戰(zhàn)略略）–usinginventoryastheleverMixedstrategy––acombinationofoneormoreofthefirstthreestrategies13ChaseStrategyProductionrateissynchronizedwithdemandbyvaryingmachinecapacityorhiringandlayingoffworkersasthedemandratevariesExpensiveifcostofvaryingcapacityishighNegativeeffectonworkforcemorale（聯(lián)想裁裁員案例例，目前前外企和和銀行都都采用外外包的方方式應(yīng)對對）ResultsinlowlevelsofinventoryShouldbeusedwheninventoryholdingcostsarehighandcostsofchangingcapacityarelow14TimeFlexibilityStrategyCanbeusedifthereisexcessmachinecapacityWorkforceiskeptstable,,butthenumberofhoursworkedisvariedovertimetosynchronizeproductionanddemandCanuseovertimeoraflexibleworkschedule（很多企企業(yè)采用用這種策策略，比比如四大大）Requiresflexibleworkforce,,butavoidsmoraleproblemsofthechasestrategyLowlevelsofinventory,lowerutilizationShouldbeusedwheninventoryholdingcostsarehighandcapacityisrelativelyinexpensive15LevelStrategyMaintainstablemachinecapacityandworkforcelevelswithaconstantoutputrateShortagesandsurplusesresultinfluctuationsininventorylevelsovertimeInventoriesthatarebuiltupinanticipationoffuturedemandorbacklogsarecarriedoverfromhightolowdemandperiodsBetterforworkermoraleLargeinventoriesandbacklogsmayaccumulateShouldbeusedwheninventoryholdingandbacklogcostsarerelativelylow16AggregatePlanningStrategies進(jìn)一步的的思考生活和學(xué)學(xué)習(xí)中，，我們都都會(huì)不自自覺的采采用這幾幾種戰(zhàn)略略，比如如考試；；哪種策略略更好？？大家可可以思考考一下。。“如果每每天針對對某個(gè)領(lǐng)領(lǐng)域純工工作時(shí)間間能有6個(gè)小時(shí)，，10年以后一一定在這這個(gè)領(lǐng)域域非常了了不起。?！蓖扑]的書書籍和博博客：《奇特的一一生》/blog//bp//QmMZyS1NQP/blog//bp//QmmNlSZhEP/blog//bp//QgVEhrQsIP17AggregateplanningusinglinearprogrammingThelimitationsofspreadsheetbasedapproachesforsolvingaggregateplanningproblems..Ahighlyeffectivetoolforacompanytousewhenittriestomaximizeprofitswhilebeingsubjecttoaseriesofconstraintsislinearprogramming..Linearprogrammingfindsthesolutionthatcreatesthehighestprofitwhilesatisfyingtheconstraintsthatthecompanyfaces.18AggregatePlanningatRedTomatoTools19AggregatePlanningatRedTomatoTools20AggregatePlanningatRedTomatoTools21Table8.1DemandForecastatRedTomatoTools22Table8.2CostsforRedTomato23步驟一、、確定決決策變量量Wt=Workforcesizeformontht,t=1,,....,6Ht=Numberofemployeeshiredatthebeginningofmontht,t=1,,....,6Lt=Numberofemployeeslaidoffatthebeginningofmontht,t=1,,....,6Pt=Productioninmontht,t=1,,....,6It=Inventoryattheendofmontht,t=1,,....,6St=Numberofunitsstockedoutattheendofmontht,t=1,,....,6Ct=Numberofunitssubcontractedformontht,t=1,,....,6Ot=Numberofovertimehoursworkedinmontht,t=1,,....,624步驟二、、建立目目標(biāo)函數(shù)數(shù)Regular-timelaborcostOvertimelaborcostCostofhiringandlayoffsCostofinventoryandstockoutCostofmaterialsandsubcontracting25步驟二、、建立目目標(biāo)函數(shù)數(shù)(8.1)26Subjectto(8.2)(8.3)(8.4)(8.5)(*)

(8.2):Workforce,hiring,,andlayoffconstraints;;(8.3)):Capacityconstraints;((8..4)::Inventorybalanceconstraints;((8.5):overtimelimitconstraints;;(**):nonnegativeconstraints..步驟三、、識(shí)別約約束條件件27Averageinventory==Averagetimeininventory=28Table8.3AggregatePlanningforRedTomatoPeriodHtLtWtOtItStCtPt012345600000000150000080656565656565000000010001983156795001175000000267000000000258325832583258325832583Ht:No..Hired;Lt:No..Laidoff;Wt:Workforcesize;;Ot:Overtime;It:Inventory;St:Stockout;Ct:Subcontract;;Pt:Production.29步驟四、、用EXCEL求解FirstStepistobuildatablecontainingeachdecisionvariableABCDEFGHIJ123PeriodHtLtWtOtItStCtPtDt40008001000005100000000160062000000003000730000000032008400000000380095000000002200106000000002200AggregatePlanDecisionVariables30步驟四、、用EXCEL求解Secondstepistoconstructatablefortheconstraintsin(8.2))—(8.5))ConstraintsMNOP123WorkforceProductionInventoryOvertime45-800-6000600-30000700-32000800-38000900-220001000-2200031步驟四、、用EXCEL求解CellCellFormulaEquationCopiedtoM5=D5-D4-B5+C58.2M6:M10N5=40*D5+E5/4-I58.3B6:N10O5=F4-G4+I5+H5-J5-F5+G58.4O6:O10P5=-E5+10*D58.5P6:P1032AggregatePlanninginExcelThethirdStepistocreateacellcontainingtheobjectivefunctionAggregatePlanCostsABCDEFGHI121314PeriodHtLtWtOtItStCtPt1510000000016200000000173000000001840000000019500000000206000000002122TotalCost=$$33步驟四、、用EXCEL求解TheFourthStepistousetheTools||SolvertoinvokeSolverSetTargetCell::C22Equalto:SelectMinBychangingcell:B5:I10Subjecttotheconstraints:B5:I10>>=0{{Alldecisionvariablesarenonnegative}F10>>=500{{Inventoryattheendofperiod6isatleast500}G10==0{{Stockoutattheendofperiod6equals0}M5:M10==0N5:N10>>=0O5:O10==0P5:P10>>=034ResultsTotalcostoverplanninghorizon==$422275Revenueoverplanninghorizon==Averageseasonalinventory

Averageflowtime==35Scenarios--敏感性分分析Increaseddemandfluctuation(Example8..1)Increaseinholdingcost((from$$2to$$6))(Example8..2)36Example8..1AllthedataareexactlythesameasinourpreviousdiscussionofRedTomato,exceptforthedemandforecastshowninfollowingTable.Obtaintheaggregateplaninthiscase37Table8.5OptimalAggregatePlanforDemandinexample8.1PeriodHtLtWtOtItStCtPt012345600000000150000080656565656565000000010002583216795001175000000126768300000000258325832583258325832583Ht:No..Hired;Lt:No..Laidoff;Wt:Workforcesize;;Ot:Overtime;It:Inventory;St:S