財(cái)務(wù)管理與財(cái)務(wù)分析運(yùn)營(yíng)管理

財(cái)務(wù)管理與財(cái)務(wù)分析運(yùn)營(yíng)管理課件

2IInventorySystemsforIndependentDemand?Basicfixedorderquantitysystem–ConstantDemand–Uncertaindemand?Basicfixedtimeperiodsystem?Newsvendormodel?SupplychaincontractOPERATIONSMANAGEMENTCLASS3I4PurposesofInventory1.Tomaintainindependenceofoperations2.Tomeetvariationinproductdemand3.Toallowflexibilityinproductionscheduling4.Toprovideasafeguardforvariationinrawmaterialdeliverytime5.Totakeadvantageofeconomicpurchase-ordersize4I5I6IInventoryCosts?Holding(orcarrying)costs?Setup(orproductionchange)costs?Orderingcosts?Shortagecosts....7IClassifyingIndependentDemandSystems?Fixed-OrderQuantity–Thereorderpoint

?Fixed-TimePeriod

?HybridSystems-BothTogether-OrderPeriodicallyunlesswereachthereorderpoint.8IInventorySystemsforIndependentDemand?Basicfixedorderquantitysystem–ConstantDemand–Uncertaindemand?Basicfixedtimeperiodsystem?Newsvendormodel?SupplychaincontractOPERATIONSMANAGEMENTCLASS9IFixed-OrderQuantityModelsEconomicOrderQuantity(EOQ):Assumptions?Demandfortheproductisconstantanduniformthroughouttheperiod?Leadtime(deliverytimeoftheorder)isconstant?Priceperunitofproductisconstant....10IFixed-OrderQuantityModelsEconomicOrderQuantity:Assumptions(cont'd)

?Inventoryholdingcostisbasedonaverageinventory.?Orderingorsetupcostsareconstant.?Alldemandsfortheproductwillbesatisfied(Nolostsalesareallowed)....11IEOQ:ASIMPLEMODEL?BookStoreMugSales–Demandisconstant,at20unitsaweek–Fixedordercostof$12,noleadtime–Holdingcostof25%ofinventoryvalueannually–Mugscost$1.00,sellfor$5.00?Question–Howmany,whentoorder12IEOQModel--BasicFixed-OrderQuantityModelR=Reorderpoint=L*dQ=EconomicorderquantityL=Leadtimed=DemandperUnitofTimeLLQQQRTimeNumberofunitsonhand....13ICostMinimizationGoalAnnualOrderingCostsHoldingCostsQOPTOrderQuantity(Q)COSTAnnualCostofItems(DC)TotalCost....TAHC=H*(Q/2)TAOC=S*D/QTAC=TAHC+TAOCS:costofplacinganorderorsetupcost14IBasicFixed-OrderQuantityModelTC=

DC

+

DQ

S

+

Q2

HTotalAnnualCost=AnnualPurchaseCostTotalAnnualOrderingCostTotalAnnualHoldingCost++TCTotalannualcostDDemandCCostperunitQOrderquantitySCostofplacinganorder

orsetupcostRReorderpointLLeadtimeHAnnualholdingandstoragecost

perunitofinventory....15IDerivingtheEOQ-CalculusMethod?Usingcalculus,wetakethederivativeofthetotalcostfunctionandsetthederivative(slope)equaltozero....Q

=

2DSH

=

2(Annual

Demand)(Order

or

Setup

Cost)Annual

Holding

CostOPT

Reorder

point,

R

=

d

L_d=

average

daily

demand

(constant)

L=

Lead

time

(constant)_16I?RecognizingTAHC=TAOCatOptimal?TAHC=H*Q/2TAOC=S*D/Q?H*Q/2=S*D/Q,SolvingforQYields:Q

=

2DSH

=

2(Annual

Demand)(Order

or

Setup

Cost)Annual

Holding

CostOPT

Reorder

point,

R

=

d

L_d=

average

daily

demand

(constant)

L=

Lead

time

(constant)_DerivingtheEOQ-GraphicalMethod17IEOQ:OPTIMALORDERQUANTITY?OptimalQuantity=

?Soforourproblem,theoptimalquantityis316

(2*Demand*SetupCost)/holdingcost18IEOQExampleAnnualDemand=1,000unitsDaysperyearconsideredinaveragedailydemand=365Costtoplaceanorder=$10Holdingcostperunitperyear=$2.50Leadtime=7daysCostperunit=$15Determinetheeconomicorderquantityandthereorderpoint.....19ISolutiond

=

1,000

units/year365

days/year

=

2.74

units/dayQ

=

2DSH

=

2(1,000

)(10)2.50

=

89.443

units

or

OPT90

units

Reorder

point,

R=

d

L=

2.74units/day

(7days)

=

19.18

or

_20

unitsWhydoweroundup?....20IIn-ClassExerciseAnnualDemand=10,000unitsDaysperyearconsideredinaveragedailydemand=365Costtoplaceanorder=$10Holdingcostperunitperyear=10%ofcostperunitLeadtime=10daysCostperunit=$15Determinetheeconomicorderquantityandthereorderpoint.Note:(Taghidden-slideicontoprojectsolution)....22IInventorySystemsforIndependentDemand?Thedefinitionandpurposeofinventory?Inventorycosts?Basicfixedorderquantitysystem–ConstantDemand–Uncertaindemand?CustomerService-AchievingPercentFillRates?Basicfixedtimeperiodsystem?NewsvendormodelOPERATIONSMANAGEMENTCLASS23IAchievingHighCustomerService

?Addbufferstock?Orderearlier?Achievedesiredcustomerservice?Percentfillrate=.99=9,900/10,000aresupplieddirectlyfromstockFixedOrderQuantitySystemUnderUncertainty24IAddingSafetyStocktoOrderEarlier?FixedOrderQuantitySystemUnderUncertaintyR=ReorderpointQ=EconomicorderquantityL=Leadtime?L=StandardErrorofEstimateDuringLeadtimeB=BufferstocksettoachievePLLQQQR=dL+B=dL+Z?L

TimeB=Addbufferstockincasedemandduringleadtime>expectedd*L25ISTRATEGICIMPORTANCEOF%FILL(P)?Pissetbytopmanagement?Pisstrategicperformancemeasure?P=99.8isbecomingmorecommon?HowdowecontrolinventoriestoachieveP?26ITHEVARIANCELAWIfXandYaretwoindependentrandomvariablesandZ=X+YthenE(Z)=E(X)+E(Y)and?Z2=?X2+?Y2

WhatifZ=X-Y?

.27IForecastingdemandduringleadtime?MEANDEMAND=d*L?WhereLislengthofleadtime?AssumeL=3,?d=standarddeviationinforecastingofdemand??L=standarddeviationduringleadtime.??L=?d

?ThisAssumesDemandisNormallyIndependentlyDistributed?ThisAllowstheUseoftheE(Z)ConceptL28ISTATISTICALINVENTORYCONTROLSCIENTIFICINVENTORYCONTROL?Setthereorderpointtoyielddesiredpercentfill(P)?R=dL+Z?L=Mean+BufferStockwhere?R=ReorderPoint?dL=MeanDemandDuringLeadtime?

?

L=StandardErrorofForecastDuringLT?Z=ValueDeterminedtoAchieveP29I?(1-P)D=NumberofUnitsShortPerYear?E(Z)=Unitsshorteachordercyclewhen?

Lis1.?NumberofUnitsShortPerYear=E(Z)*?

L*D/Q?EquatingBoth?E(Z)*?

L*D/Q=(1-P)Drearranging:?E(Z)=(1-P)Q/?

LDeterminingtheValueofZ:ServicelevelE(Z)Z30IInventorySystemsforIndependentDemand?Thedefinitionandpurposeofinventory?Inventorycosts?Basicfixedorderquantitysystem–ConstantDemand–Uncertaindemand?CustomerService-AchievingPercentFillRates?Basicfixedtimeperiodsystem?NewsvendormodelOPERATIONSMANAGEMENTCLASS31IInventoryManagementUsingMarginal?One-PeriodModel?ClassicallyCalledtheNewsvendorProblem?ItemsOrderedOnly?Toomany–thenonlysalvagevalue?Toolittle–lostcustomers32INewsvendor:Exercise?Anequipmentrepairfirmwishestoorderenoughsparepartstokeepmachinesrunningthroughoutatradeshow.?Therepairmansellthepartsat$95eachifneededforarepair.?Hepays$70forthecostofeachpart.?Ifallthepartsarenotneeded,theymaybereturnedtothesupplierforacreditof$50each.

?Thedemandforthepartsisestimated.33INewsvendor:ExerciseNumberof

Frequencyparts

ofNeed

0

0.10

1

0.15

2

0.20

3

0.30

4

0.20

5

0.0534INewsvendor:Exercise

Numberof

Frequencyparts

ofNeed

CPn

0

0.10

0.10