供应链管理(第11、12讲)

1、 2007 Pearson Education10-1Chapter 7Managing Economies of Scale in the Supply Chain: Cycle InventorySupply Chain Management 2007 Pearson Education10-2OutlineuRole of Cycle Inventory in a Supply ChainuEconomies of Scale to Exploit Fixed CostsuEconomies of Scale to Exploit Quantity DiscountsuShort-Ter

2、m Discounting: Trade PromotionsuEstimating Cycle Inventory-Related Costs in Practice 2007 Pearson Education10-3第第7 7章章 获取供应链规模经济的手段：获取供应链规模经济的手段：循环库存循环库存u一、循环库存在供应链中的作用u二、利用固定成本获取规模经济u三、利用数量折扣获取规模经济u四、短期折扣：商业促销u五、在实践中估测与循环库存相关的费用 2007 Pearson Education10-4循环库存产生原因循环库存产生原因u规模经济u大批量生产与采购u订购与运输u数量折扣与促销

3、 2007 Pearson Education10-5Role of Inventory in the Supply ChainImprove Matching of Supplyand DemandImproved ForecastingReduce Material Flow TimeReduce Waiting TimeReduce Buffer InventoryEconomies of ScaleSupply / DemandVariabilitySeasonalVariabilityCycle InventorySafety InventorySeasonal Inventory

4、2007 Pearson Education10-6Role of Cycle Inventoryin a Supply ChainuLot, or batch size: quantity that a supply chain stage either produces or orders at a given timeuCycle inventory: average inventory that builds up in the supply chain because a supply chain stage either produces or purchases in lots

5、that are larger than those demanded by the customer Q = lot or batch size of an order D = demand per unit timeuInventory profile: plot of the inventory level over time (Fig. 7.1)uCycle inventory = Q/2 (depends directly on lot size)uAverage flow time = Avg inventory / Avg flow rateuAverage flow time

6、from cycle inventory = Q/(2D) 2007 Pearson Education10-7Role of Cycle Inventoryin a Supply ChainQ = 1000 unitsD = 100 units/dayCycle inventory = Q/2 = 1000/2 = 500 = Avg inventory level from cycle inventoryAvg flow time = Q/2D = 1000/(2)(100) = 5 daysuCycle inventory adds 5 days to the time a unit s

7、pends in the supply chainuLower cycle inventory is better because: Average flow time is lower Working capital requirements are lower Lower inventory holding costs 2007 Pearson Education10-8Role of Cycle Inventoryin a Supply ChainuCycle inventory is held primarily to take advantage of economies of sc

8、ale in the supply chainuSupply chain costs influenced by lot size: Material cost = C Fixed ordering cost = S Holding cost = H = hC (h = cost of holding $1 in inventory for one year)uPrimary role of cycle inventory is to allow different stages to purchase product in lot sizes that minimize the sum of

9、 material, ordering, and holding costsuIdeally, cycle inventory decisions should consider costs across the entire supply chain, but in practice, each stage generally makes its own supply chain decisions increases total cycle inventory and total costs in the supply chain 2007 Pearson Education10-9循环库

10、存在供应链中的作用循环库存在供应链中的作用u 循环库存指供应链中建立的平均库存量u Q：订购批量u R：单位时间需求量（假设需求量不变）u 循环库存批量库存/2Q/2u 循环库存平均周转时间循环库存/需求量Q/2Ru 为减少市场波动，公司理想循环库存一般较小TQ 2007 Pearson Education10-10Economies of Scaleto Exploit Fixed CostsuHow do you decide whether to go shopping at a convenience store or at Sams Club?uLot sizing for a si

11、ngle product (EOQ) 2007 Pearson Education10-11Economies of Scaleto Exploit Fixed CostsAnnual demand = DNumber of orders per year = D/QAnnual material cost = CDAnnual order cost = (D/Q)SAnnual holding cost = (Q/2)H = (Q/2)hCTotal annual cost = TC = CD + (D/Q)S + (Q/2)hCFigure 7.2 shows variation in d

12、ifferent costs for different lot sizes 2007 Pearson Education10-12Fixed Costs: Optimal Lot Sizeand Reorder Interval (EOQ) D:Annual demand S: Setup or Order CostC:Cost per unith: Holding cost per year as a fraction of product costH:Holding cost per unit per yearQ:Lot SizeT: Reorder intervalMaterial c

13、ost is constant and therefore is not considered in this modelDHSnHDSQhCH2*2* 2007 Pearson Education10-13利用固定成本获取规模经济利用固定成本获取规模经济u 单一产品批量规模Q（经济订购批量）u R产品年需求量u S每次订购固定成本u C单位产品购买价格成本u H每年存储成本u 年原料价格成本CRu 年订购次数R/Qu 年订购成本（R/Q）*Su 年存储成本（Q/2）H=(Q/2)hcu 年总成本TC CR+ （R/Q）*S+ （Q/2）hc 2007 Pearson Education10-

14、14u年总成本TC CR+ （R/Q）*S+ （Q/2）hcu等式右边对q一阶求导，等于0时，得最佳订购批量uQ*=u注：h和R必须要有相同时间单位unR/Q*2RChS2RSCh 2007 Pearson Education10-15批量规模成本总成本储存成本订购成本原材料成本Q* 2007 Pearson Education10-16Example 7.1Demand, D = 12,000 computers per yeard = 1000 computers/monthUnit cost, C = $500Holding cost fraction, h = 0.2Fixed cos

15、t, S = $4,000/orderQ* = Sqrt(2)(12000)(4000)/(0.2)(500) = 980 computers Cycle inventory = Q/2 = 490Flow time = Q/2d = 980/(2)(1000) = 0.49 monthReorder interval, T = 0.98 month 2007 Pearson Education10-17Example 7.1 (continued)Annual ordering and holding cost = = (12000/980)(4000) + (980/2)(0.2)(500

16、) = $97,980Suppose lot size is reduced to Q=200, which would reduce flow time:Annual ordering and holding cost = = (12000/200)(4000) + (200/2)(0.2)(500) = $250,000To make it economically feasible to reduce lot size, the fixed cost associated with each lot would have to be reduced 2007 Pearson Educat

17、ion10-18Example 7.2If desired lot size = Q* = 200 units, what would S haveto be?D = 12000 unitsC = $500h = 0.2Use EOQ equation and solve for S:S = hC(Q*)2/2D = (0.2)(500)(200)2/(2)(12000) = $166.67To reduce optimal lot size by a factor of k, the fixed order cost must be reduced by a factor of k2 200

18、7 Pearson Education10-19例：例：best buybest buy公司采购电脑，月需求公司采购电脑，月需求10001000台，固定成本每次台，固定成本每次40004000，进价，进价每台每台500500，零售商库存成本占，零售商库存成本占2020，求，求Q Q* *u解：年需求量R=1000*12=12000u每批订购成本S=4000u单位采购成本C=500u年存储成本h0.2uQ*=（2*12000*4000）/（0.2*500） ）1/2980u循环库存Q*/2=490u年订购次数R/Q*=120000/980=12.24u订购和存储成本（R/Q*）S+（Q*/2）h

19、C=97980u平均周转时间Q*/2R=490/1200=0.041年0.49月 2007 Pearson Education10-20u拓展：uA、如果批量规模1100，而不是980，则：u订购次数12000/110010.9u总成本10.9*4000+1100/2*0.2*50043600+5500098600u批量规模从980到1100，增加10，总成本从97980到98600，仅增加0.6。 2007 Pearson Education10-21uB、假设月需求增加到4000每月（增长4倍），最佳规模批量和订购次数各自增加2倍，平均周转时间减少至1/2。uQ*=u年订购次数R/Q*u平

20、均周转时间Q*/2Ru结论：如果批量规模最佳，需求量增加，循环库存周转时间会减少。 2007 Pearson Education10-22u C、如果批量规模为200，则：u 年库存成本u （R/Q）*S+(Q/2)hCu （ 12*1000/200 ）*4000+（200/2）0.2*500u =250000 97980u 为了减少批量规模，只能减少固定成本。如果期望批量规模为200，则u Q*=u S=(hC(Q*）2)/ (2*R)u =0.2*500*200*200/(2*12000)=166.7C1Cr uThe objective for the company (a retail

21、er in our example) is to decide on a lot size that will minimize the sum of material, order, and holding costs 2007 Pearson Education10-27All-Unit Quantity Discount Procedure (different from what is in the textbook)Step 1: Calculate the EOQ for the lowest price. If it is feasible (i.e., this order q

22、uantity is in the range for that price), then stop. This is the optimal lot size. Calculate TC for this lot size.Step 2: If the EOQ is not feasible, calculate the TC for this price and the smallest quantity for that price.Step 3: Calculate the EOQ for the next lowest price. If it is feasible, stop a

23、nd calculate the TC for that quantity and price.Step 4: Compare the TC for Steps 2 and 3. Choose the quantity corresponding to the lowest TC. Step 5: If the EOQ in Step 3 is not feasible, repeat Steps 2, 3, and 4 until a feasible EOQ is found. 2007 Pearson Education10-28All-Unit Quantity Discounts:

24、ExampleCost/Unit$3$2.96$2.92Order Quantity5,00010,000Order Quantity5,00010,000Total Material Cost 2007 Pearson Education10-29All-Unit Quantity Discount: ExampleOrder quantityUnit Price0-5000$3.005001-10000$2.96Over 10000$2.92q0 = 0, q1 = 5000, q2 = 10000C0 = $3.00, C1 = $2.96, C2 = $2.92D = 120000 u

25、nits/year, S = $100/lot, h = 0.2 2007 Pearson Education10-30All-Unit Quantity Discount: ExampleStep 1: Calculate Q2* = Sqrt(2DS)/hC2 = Sqrt(2)(120000)(100)/(0.2)(2.92) = 6410Not feasible (6410 10001)Calculate TC2 using C2 = $2.92 and q2 = 10001TC2 = (120000/10001)(100)+(10001/2)(0.2)(2.92)+(120000)(

26、2.92)= $354,520Step 2: Calculate Q1* = Sqrt(2DS)/hC1=Sqrt(2)(120000)(100)/(0.2)(2.96) = 6367Feasible (5000636710000) StopTC1 = (120000/6367)(100)+(6367/2)(0.2)(2.96)+(120000)(2.96)= $358,969TC2 TC1 The optimal order quantity Q* is q2 = 10001 2007 Pearson Education10-31All-Unit Quantity DiscountsuSup

27、pose fixed order cost were reduced to $4 Without discount, Q* would be reduced to 1265 units With discount, optimal lot size would still be 10001 unitsuWhat is the effect of such a discount schedule? Retailers are encouraged to increase the size of their orders Average inventory (cycle inventory) in

28、 the supply chain is increased Average flow time is increased Is an all-unit quantity discount an advantage in the supply chain? 2007 Pearson Education10-32利用数量折扣获取规模经济利用数量折扣获取规模经济u全部单位数量折扣uqiQiqi+1uTCi（R/Qi）S+(Qi/2)+RCi 2007 Pearson Education10-33月需求量1000订购成本100储存成本20%订购数量单价0-500035001-100002.96100

29、00-2.92Drug online 2007 Pearson Education10-34u 解：q00，q15000，q210000u C03，C12.96，C22.92u R=120000,S=100,h0.2u Q0*=(2RS/hC)1/2 (2*120000*100/3*0.2)1/2 6324u q15000时，u TC0=(R/q1)S+(q1/2)hC1+RC1=120000/5000*100+5000/2*0.2*2.96+120000*2.96359080u Q1*=(2RS/hC)1/2 (2*12000*100/2.96*0.2)1/2 6367u Q1*=6367时

30、，u TC1=(R/Q1)S+(Q1/2)hC+RC1=358969u Q2*=(2RS/hC)1/2 (2*12000*100/3*0.2)1/2 6410u q2=10000时，u TC2=(R/q2)S+(q1/2)hC+RC1=354520 2007 Pearson Education10-35Why Quantity Discounts?uCoordination in the supply chain Commodity products Products with demand curve 2-part tariffs Volume discounts 2007 Pearson

31、Education10-36Coordination forCommodity ProductsuD = 120,000 bottles/yearuSR = $100, hR = 0.2, CR = $3uSS = $250, hS = 0.2, CS = $2Retailers optimal lot size = 6,324 bottlesRetailer cost = $3,795; Supplier cost = $6,009Supply chain cost = $9,804 2007 Pearson Education10-37Coordination forCommodity P

32、roductsuWhat can the supplier do to decrease supply chain costs? Coordinated lot size: 9,165; Retailer cost = $4,059; Supplier cost = $5,106; Supply chain cost = $9,165uEffective pricing schemes All-unit quantity discount $3 for lots below 9,165 $2.9978 for lots of 9,165 or more Pass some fixed cost

33、 to retailer (enough that he raises order size from 6,324 to 9,165) 2007 Pearson Education10-38Quantity Discounts WhenFirm Has Market PoweruNo inventory related costsuDemand curve360,000 - 60,000pWhat are the optimal prices and profits in the following situations? The two stages coordinate the prici

34、ng decision Price = $4, Profit = $240,000, Demand = 120,000 The two stages make the pricing decision independently Price = $5, Profit = $180,000, Demand = 60,000 2007 Pearson Education10-39Two-Part Tariffs andVolume DiscountsuDesign a two-part tariff that achieves the coordinated solutionuDesign a v

35、olume discount scheme that achieves the coordinated solutionuImpact of inventory costs Pass on some fixed costs with above pricing 2007 Pearson Education10-40Lessons from Discounting SchemesuLot size based discounts increase lot size and cycle inventory in the supply chainuLot size based discounts a

36、re justified to achieve coordination for commodity productsuVolume based discounts with some fixed cost passed on to retailer are more effective in general Volume based discounts are better over rolling horizon 2007 Pearson Education10-41u为什么采取数量折扣的策略u1）供应链的协调u如果供应链是纵向一体化，且每一阶段运作均考虑供应链总体利润，则可以实现协调运作

37、，但是，产权的差异，导致各阶段追求各自利益最大化。 2007 Pearson Education10-42u A、对最终产品数量折扣案例u Vitamin co：R10000，S100，h20，Cm3；u 计算出Q*6324，TC3795u 制造商：S250，C02，h20。u 制造商订购成本120000/6324*2504744u 制造商年存储成本6324/2*2*0.21265u 总成本4744+12656009u 供应链总成本6009+37959804u 如果Q*9165，则：u 供应链总成本120000/9165*100+9165/2*3*0.2+ 120000/9165*250+91

38、65/2*2*0.2 4059+51069165u 结论：制造商会通过数量折扣让度部分利益，实现总体利益最大化 2007 Pearson Education10-43u引论：u以批量折扣为基础的折扣降低了供应链总成本，但增加了零售商采购批量，增加了供应链循环库存。u如果制造商致力于降低其建设成本和订购成本时，规模折扣就会发生改变。但实际情况却是，生产运作部门降低固定成本，营销部门提供数量折扣？！（思考） 2007 Pearson Education10-44uB、对公司有市场控制权的产品实行数量折扣u案例：某药品市场需求曲线q=360000-60000p。制造商成本c0=2，批发价c1=4。u

39、r销=（360000-60000p）p-（360000-60000p）c1ur=360000-120000p+60000c1=0uP=5 q=60000 r销=60000 r制=120000 r供=18000u整合后：p=4 q=120000 r供=180000 2007 Pearson Education10-45u协调方法：u第一种、两部分定价：u制造商先索取全部利润作为前期特许经营费，再将产品以成本出售u第二种、以总量为基础的数量折扣uQ12000,p=3.5u注意：零售商在期末加大采购，即曲棍球现象。u对策：将总量折扣建立在滚动水平基础上（以过去12周或者90天销售量为基础） 2007

40、 Pearson Education10-46u2）利用差别定价使供应链利润最大化顾客剩余厂商收益需求曲线供给曲线 2007 Pearson Education10-47Short-Term Discounting: Trade PromotionsuTrade promotions are price discounts for a limited period of time (also may require specific actions from retailers, such as displays, advertising, etc.)uKey goals for promot

41、ions from a manufacturers perspective: Induce retailers to use price discounts, displays, advertising to increase sales Shift inventory from the manufacturer to the retailer and customer Defend a brand against competition Goals are not always achieved by a trade promotionuWhat is the impact on the b

42、ehavior of the retailer and on the performance of the supply chain?uRetailer has two primary options in response to a promotion: Pass through some or all of the promotion to customers to spur sales Purchase in greater quantity during promotion period to take advantage of temporary price reduction, b

43、ut pass through very little of savings to customers 2007 Pearson Education10-48Short Term DiscountingQ*: Normal order quantityC: Normal unit costd: Short term discountD: Annual demandh: Cost of holding $1 per yearQd: Short term order quantitydCChdCdDQQd-+)-(=*Forward buy = Qd - Q* 2007 Pearson Educa

44、tion10-49Short Term Discounts:Forward BuyingNormal order size, Q* = 6,324 bottles Normal cost, C = $3 per bottleDiscount per tube, d = $0.15Annual demand, D = 120,000Holding cost, h = 0.2Qd =Forward buy = 2007 Pearson Education10-50Promotion Pass Throughto ConsumersDemand curve at retailer: 300,000

45、- 60,000pNormal supplier price, CR = $3.00 Optimal retail price = $4.00 Customer demand = 60,000Promotion discount = $0.15 Optimal retail price = $3.925 Customer demand = 64,500Retailer only passes through half the promotion discount and demand increases by only 7.5% 2007 Pearson Education10-51Trade

46、 PromotionsuWhen a manufacturer offers a promotion, the goal for the manufacturer is to take actions (countermeasures) to discourage forward buying in the supply chainuCounter measures EDLP Scan based promotions Customer coupons 2007 Pearson Education10-52短期折扣：商业促销短期折扣：商业促销u制造商目的：引导零售商通过价格折扣、展示或者广告宣

47、传刺激销售；制造商库存转移；品牌竞争u经销商选择：u将一部分或者全部促销优惠让度给消费者，刺激销售；只是让度一小部分，大批购进，缓慢销售。 2007 Pearson Education10-53u折扣价格下的最优订购数量：u假设：折扣仅提供一次；Qd是Q*的倍数；零售商不将优惠让度给顾客。uQddR/（C-d）h+CQ*/(C-d)u超前采购量 Qd- Q*u如果零售商知道下一个促销时间，设为Q1，则会选择Q1和Qd的最小值。 2007 Pearson Education10-54案例：案例：DODO公司公司R=120000,CM=3,hR=120000,CM=3,h0.20.2，Q Q* *=6324,d=6324,d0.150.15，求零售商订，求零售商订购数量？购数量？u QddR/（C-d）h+CQ*/(C-d)u 0.15*120000/（3-0.15）0.2+3*6324/（3-0.15）38236u 循环库存19118u 平均周转时间38236/2*120000u 0.16年1.9118月u 超前采购量38236-632431912u DO公司在今后3个月将不采购！导致零售商库存大增。只有当制造商无意建立了大量剩余库存，或者想使低谷期需求量增加，才会支持超前采购。实际上，制造商经常根据预测的计划促销活动建立库存。