兩種產品需求不確定下單期零組件採購量及共用零組件分配問題之探討

Abstract

ATO業者為了縮短訂單的交期會先預測訂單需求儲存適量的零組件，然而顧客需求難於準確預測。ATO業者常面臨某些產品是高庫存低需求，另一些產品是低庫存高需求的窘境。為應付上述窘境，業者開發零組件共用於多項產品，共用零組件會因為風險共擔（risk-pooling）的效益減少存貨成本，增加利潤。 本研究考慮兩種產品分別為高利潤與低利潤產品。各產品分別由兩種零組件組裝而成，低利潤產品的某一零組件（稱之為特殊零組件）不足時，亦可用較高價使用於高利潤產品的零組件，稱之為共用零組件。當因兩種產品的訂單到達先後不確定，在低利潤產品訂單先到的情況下，若已無特殊零組件可用，是否該使用共用零組件？若使用共用零組件，是否會造成當高利潤訂單到達時，無共用零組件可用的情況？若留待可能到達的高利潤訂單使用，然而若高利潤訂單不足時，將造成共用零組件的存貨，低利潤訂單缺貨的問題。 本論文在給定兩種產品的需求分配下，以期望利潤最大化為目標，構建數學模型以決定各零組件的購買量以及共用零組件的分配方式。此外本研究亦進行敏感度分析，以瞭解不同情境下的管理意涵。

In this study we consider the component ordering quantities and production decision problems for a single-period assemble-to-order (ATO) production system with two end products, called high profit product and low profit product. Each product is used for fulfill a particular customer. The ordering quantity of each customer’s order is uncertain following a given distribution. These two products are assembled by two components respectively, C0 and C1 for high profit product, and C2 and C3 for low profit product. However C3 can be replaced by C0 for assembling low profit product. We called C0 as common component and C3 as special component. The unit cost of C0 is higher than C3. If the customer order of the low profit product confirms before the other one, the manufacturer needs to commitment immediately how many products to be delivered. In this case if the inventory of the special component is insufficient to fill the demand, then the manufacturer faces the decision problem: how many of the common component should be distributed to fill the unsatisfied demand. Under the above ATO environment we formulate a mathematical model for maximizing the expected profit to determine the optimal inventory levels of components and to decide how many of the common component should be distributed to fill the unsatisfied demand of low profit product. Numerical Examples are given to illustrate the model, solution procedure and to find some management insights.