存货管理与倒推式的成本制度

1、成本會計 5葉 誌 崇 教授Chapter 10 存貨管理與倒推式的成本制度Inventory Management, JIT & Back-flushing（Horngren, 12/e）l JIT的生產Just-in-Time Production1. 降低材料存貨Reducing incoming materials inventory(1) Developing long-term relationships with a limited number of vendors(2) Selecting vendors on the basis of service and qua

2、lity, aswell as price (3) Key employees 可直接向Vendors下訂單(4) Vendors將材料運到我們的 Production Floor 2. 降低在製品存貨Reducing work-in-process inventory(1) Customer-response Time (From Received PO to Shipped) Customer places order for product order received by manufacturing order is set up becomes finished good

3、s order delivered to customer(2) Reducing cycle time (manufacturing lead time) set up, processing, movement, waiting, and inspection time 3. 降低製成品存貨Reducing finished goods inventory HP生產Kayak Workstation產品合約規定：(1) 必須配合HP的Production Schedule(2) Delivery to the生產線 Production Floor而非HP 的倉庫 Warehouse(3)

4、 如果品質Quality有問題，則表示未符合合約, 可能受處 罰。May be Penalty(4) Information Technology的應用Internet to Place Purchasing Order, E-Com, Bar Code, EDI, RFIDl 存貨相關的成本Costs Associated with Goods for Sale1. Purchasing Costs2. Ordering Costs3. Carrying Costs4. Shortage Costs5. 品質成本Quality Costs（1） 預防成本Preventive Costs（2）

5、 鑑定成本Appraising Costs（3） 失敗成本Failure Costs Relevant Total Costs = Purchasing Costs + Ordering Costs + Carrying Costs + Shortage Costs + Quality Costsl Relevant Benefits and Relevant Costs of JITD 13,000台（每週250台，一年52週）Carrying Cost購價14×15% $2.1（RRR）3.15.2 Ordering Cost200EOQ 1,000台Deliveries 13,

6、000台/1,000台 13次Order Point Lead Time（2 Weeks）× 250台 500台1、 如果Ordering Cost愈小，則EOQ愈小由於Internet的引入，假設Ordering Cost從200 2訂購次數從13次 130次（即每次買100台）訂購價從1414.02RRR仍為 15持有成本每台14.02 × 15% 3.1 5.203缺貨50台Rush Order $4 Current JITPurchasing Costs $14×13,000台 $182,000 $14.02×13,000台 $182,260Or

7、dering Costs $200×13次 2,600 $2×130次 260Opportunity Carrying Costs（$3.1$14×15%）×1000台/2 2,600（$3.1$14.02×15%）×100台/2 260.15 缺貨成本(Shortage Costs) $4×50台 0 200 187,200 $182,980.15 目前EOQ1,000台，RTC 187,200，比JIT的RTC多$4,219.85，即（$187,200 $182,980.15）2、 品質成本Quality Costs假設

8、Denton公司能提供13.6，本公司願同意Internet Link到Denton訂購成本2Carrying Cost 13.6 × 153 = $5.04RTC考慮Quality Cost，即Denton Delay & Inspection Cost（1） Inspection Costs $0.05（2） Stock-out每年360台，Lost Sales $8（3） Poor Quality 退貨2%，每退一台損失25原公司購買 Denton公司Purchasing Costs $14.02 × 13,000台 $182,260 $13.6 ×

9、 13,000台 $176,800Ordering Costs $2 × 130次 $260 260 260Inspection Costs 0.05×13,000台 0 650Opportunity Carrying Costs（$3.1$14.02×15%）×100台/2 260.15（$3.0$13.6×15%）×100台/2 252 缺貨成本 (Shortage Costs) $4×50台 200 $8×360台 2,880Return Costs $25 × 13,000台 × 2%

10、0 6,500 $182,980.15 $187,342 考慮Quality Cost 後，用Internet方式向Denton公司購買較為不利，成本多$4,361.85 (187,342182,980.15)l EOQ與JIT的衝突(1) Set up Times及Set up Costs很小(2) Lead Time幾乎為零(3) 沒有Bottleneck，生產線非常順暢（Line Balance）(4) Lot Size不可以太大，否則就不能ZIP(5) 沒有缺貨、Poor Quality、Engineering Changes及任何機器 Downtime的假設l JIT and 生產速

11、度Velocity為加速Throughput Time（產出時間），Deck委外加工變成Part（1,000種材料變成10個Parts），使Bottleneck機率降低，Conveyer Speed加快，WIP降低。Moving Time, Waiting Time 及 Inspection Time並沒有附加價值，減少Total Cycle Time。l JIT and Production LossesWIP的量降低，則Production Losses自然下降l JIT的財務利益Financial Benefits(1) Lower investment in inventory(2)

12、Carrying & Handling Costs減少(3) 降低Risk of Obsolescence of Inventories(4) Lower investment in Plant Space(5) 減少Paper work, Improved Quality, 減少Spoilagel JIT - A Balanced View(1) Supplier的水平與配合度(2) 運輸成本(3) 運輸時間能否掌控(4) 低價、不重要的Material因JIT的實施而沒有Safety Stock, 致變成Critical Partl 倒推式的成本制度Back-flushing（1）收到材料借：RIP 貸：A/P（