财务管理与财务分析运营管理.ppt
财务管理与财务分析运营管理课件 2 I Inventory Systems for Independent Demand ?Basic fixed order quantity system Constant Demand Uncertain demand ?Basic fixed time period system ?Newsvendor model ?Supply chain contract OPERATIONS MANAGEMENT CLASS 3 I 4 Purposes of Inventory 1. To maintain independence of operations 2. To meet variation in product demand 3. To allow flexibility in production scheduling 4. To provide a safeguard for variation in raw material delivery time 5. To take advantage of economic purchase-order size 4 I 5 I 6 I Inventory Costs ?Holding (or carrying) costs ?Setup (or production change) costs ?Ordering costs ?Shortage costs . 7 I Classifying Independent Demand Systems ?Fixed-Order Quantity The reorder point ?Fixed-Time Period ?Hybrid Systems - Both Together - Order Periodically unless we reach the reorder point. 8 I Inventory Systems for Independent Demand ?Basic fixed order quantity system Constant Demand Uncertain demand ?Basic fixed time period system ?Newsvendor model ?Supply chain contract OPERATIONS MANAGEMENT CLASS 9 I Fixed-Order Quantity Models Economic Order Quantity (EOQ): Assumptions ?Demand for the product is constant and uniform throughout the period ?Lead time (delivery time of the order) is constant ?Price per unit of product is constant . 10 I Fixed-Order Quantity Models Economic Order Quantity: Assumptions (contd) ?Inventory holding cost is based on average inventory. ?Ordering or setup costs are constant. ?All demands for the product will be satisfied (No lost sales are allowed) . 11 I EOQ : A SIMPLE MODEL ?Book Store Mug Sales Demand is constant, at 20 units a week Fixed order cost of $12, no lead time Holding cost of 25% of inventory value annually Mugs cost $1.00, sell for $5.00 ?Question How many, when to order 12 I EOQ Model-Basic Fixed-Order Quantity Model R = Reorder point = L*d Q = Economic order quantity L = Lead time d = Demand per Unit of Time L L Q Q Q R Time Number of units on hand . 13 I Cost Minimization Goal Annual Ordering Costs Holding Costs QOPT Order Quantity (Q) C O S T Annual Cost of Items (DC) Total Cost . TAHC = H*(Q/2) TAOC = S*D/Q TAC = TAHC + TAOC S: cost of placing an order or setup cost 14 I Basic Fixed-Order Quantity Model TC = DC + DQ S + Q2 HTotal Annual Cost = Annual Purchase Cost Total Annual Ordering Cost Total Annual Holding Cost + + TC Total annual cost D Demand C Cost per unit Q Order quantity S Cost of placing an order or setup cost R Reorder point L Lead time H Annual holding and storage cost per unit of inventory . 15 I Deriving the EOQ - Calculus Method ?Using calculus, we take the derivative of the total cost function and set the derivative (slope) equal to zero . 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)_16 I ?Recognizing TAHC = TAOC at Optimal ?TAHC = H*Q/2 TAOC = S*D/Q ?H*Q/2 = S*D/Q, Solving for Q Yields: 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)_Deriving the EOQ - Graphical Method 17 I EOQ : OPTIMAL ORDER QUANTITY ?Optimal Quantity = ?So for our problem, the optimal quantity is 316 (2 * Demand * Setup Cost)/holding cost 18 I EOQ Example Annual Demand = 1,000 units Days per year considered in average daily demand = 365 Cost to place an order = $10 Holding cost per unit per year = $2.50 Lead time = 7 days Cost per unit = $15 Determine the economic order quantity and the reorder point. . 19 I Solution d = 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 /d ay (7days) = 19.18 or _20 unitsWhy do we round up? . 20 I In-Class Exercise Annual Demand = 10,000 units Days per year considered in average daily demand = 365 Cost to place an order = $10 Holding cost per unit per year = 10% of cost per unit Lead time = 10 days Cost per unit = $15 Determine the economic order quantity and the reorder point. Note: (Tag hidden-slide icon to project solution) . 22 I Inventory Systems for Independent Demand ?The definition and purpose of inventory ?Inventory costs ?Basic fixed order quantity system Constant Demand Uncertain demand ?Customer Service - Achieving Percent Fill Rates ?Basic fixed time period system ?Newsvendor model OPERATIONS MANAGEMENT CLASS 23 I Achieving High Customer Service ?Add buffer stock ?Order earlier ?Achieve desired customer service ?Percent fill rate = .99 = 9,900/10,000 are supplied directly from stock Fixed Order Quantity System Under Uncertainty 24 I Adding Safety Stock to Order Earlier ?Fixed Order Quantity System Under Uncertainty R = Reorder point Q = Economic order quantity L = Lead time ?L = Standard Error of Estimate During Leadtime B = Buffer stock set to achieve P L L Q Q Q R = dL + B = dL + Z ?L Time B = Add buffer stock in case demand during leadtime expected d*L 25 I STRATEGIC IMPORTANCE OF %FILL (P) ?
