independent-demandinventory(編輯修改稿)
2024-09-24 18:14 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 tory level. – Frequent orders (small lot size) lead to a lower average inventory size, . higher ordering cost and lower holding cost. – Fewer orders (large lot size) lead to a larger average inventory size, . lower ordering cost and higher holding cost. 1520 Figure : EOQ Inventory Levels (‘sawtooth model’) Time Lot size = Q Order Interval Average Inventory Level = Q/2 1521 Notations and measurement units in EOQ D = Demand rate, units per year S = Cost per order placed, or setup cost, dollars per order C = Unit cost, dollars per unit i = Carrying rate, percent of value per year Q = Lot size, units TC= total of ordering cost plus carrying cost 1522 Cost Equations in EOQ Ordering cost = (cost per order) x orders per year) = SD/Q Carrying cost per year = (annual carrying rate) x (unit cost) x average inventory = iCQ/2 Total annual cost (TC) = ordering cost per year + carrying cost per year = SD/Q + iCQ/2 1523 Total Cost of Inventory 1524 TC and EOQ TC = ordering cost + holding cost = S*(D/Q) + iC*(Q/2) EOQ = note: Although we have used annual costs, any time period is all right. Just be consistent! The same is true for currency designations. iCSDQ 2?1525 EOQ Example Sales = 10 cases/week S = $12/order i = 30 pct/year C = $80/case _________ EOQ = ? (2SD)/iC = SQRT[(2*12*10*52)/(80*.3)] = SQRT[12,480/24] = cases/order TC = ordering cost + holding cost = S*(D/Q) + iC*(Q/2) = 10(520/) + 24 * = + = $If order 22 cases instead, TC = $。 if 23, TC = $ 1526 EOQ Example T o t a l I n v e n t o r y C o s t020040060080013 17 21 24 28 32 36 40O rd e r Si z eDollars1527 Continuous Review System Relax assumption of constant demand. Demand is assumed to be random. Check inventory position each time there is a demand ( continuously). If inventory position drops below the reorder point, place an order for the EOQ. Also called fixedorderquantity or Q system (the fixed order size is EOQ). 1528 Figure : A Continuous Review (Q) System R = Reorder Point Q = Order Quantity L = Lead time 1529 A Continuous Review (Q) System Amount to order = EOQ Order when inventory position = reorder point. Reorder point = lead time * demand/period = R = lead time demand (when demand is constant) Reorder point is independent of EOQ! EOQ tells how much to order. Re
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