採用即時可允諾量機制之發光二極體供應鏈之績效分析

Performance Analysis of a LED Supply Chain Using Real-Time Available-To-Promise Mechanisms

供應鏈是一種分散式環境，其特性是企業之間以相互連結的方式所形成的供需網路來滿足顧客需求。然而在滿足顧客需求的前提下，如何使供應鏈間的成員透過資訊的正確掌握與互相溝通的合作與協定機制，對供應鏈的執行績效與目標管理是非常重要的。台灣LED（發光二極體）產業具有分散式製造環境的特性，每一段的生產型態與製程皆不相同，如何透過資訊分享以達成供應鏈的總體目標，已經成為了這個產業重要的課題。實務上，當一客戶提出訂購要求時，即時可允諾量必須根據系統資源之可用性，評估是否能在客戶所指定之交期前交貨，藉以決定是否應接受該訂單。可能的系統資源包括：完成品庫存、在製品量、原物料庫存、生產排程、以及其他考量（如成本）等。如果根據系統資源之可用性，可允諾量估計無法在客戶所指定之交期前交貨，則製造商必須立即拒絕該訂單。本研究探討一典型的LED供應鏈，供應鏈成員包括：物料／零件供應商、製造商、與客戶。客戶訂單抵達之後，製造商根據可允諾量機制決定是否接受該訂單，如果是接受該訂單，則製造商會根據訂單之需求進行生產作業，並在客戶所指定的交期之前將完成品運送到客戶處。本研究提出一個以模擬為基礎之研究架構，以探討各實驗變數（包括：可允諾量機制、各種不確定性等）對LED供應鏈之影響程度。本研究所採用的績效指標包括：總利潤、達交率、流程時間、與被拒絕訂單比率。本研究並以一個實際的LED供應鏈為個案，以示範所提出的研究架構。個案分析結果顯示，一般而言，若以被拒絕訂單比率為主要的績效指標，以可允諾量機制一（代表較鬆條件）表現較佳；若以達交率或流程時間為主要的績效指標，則以可允諾量機制二或三（代表較嚴條件）表現較佳。

Supply chain is one kind of distributed environments; the main characteristic of a supply chain is to fulfill the customer's needs by a supply-demand network composed of businesses. To fulfill the needs of customers, the information and cooperation mechanism shall be correctly communicated, which is very important for the performance evaluation and target management of a supply chain. Light-Emitting Diode (LED) industry in Taiwan is characterized by distributed manufacturing. The processes are different in each phase and the essential issue is to meet the goal of the supply chain by information sharing. In practice, real-time available-to-promise (ATP) suggests that when a customer request is initiated, ATP determines the availability of system resource based on the customer requested due date. The system resource includes finished goods inventory, work-in-process, raw materials inventory, production scheduling, as well as other considerations such as cost. When considering availability, if an entire order cannot be filled it is rejected from the system. This study chooses a typical LED supply chain that includes the following members: materials/parts suppliers, manufacturer, and customers. When a customer request is initiated, the manufacturer will decide if the order is accepted based on real-time ATP. If the order is accepted, the manufacturer will produce the required products based on the customer requested due date. This study proposes a simulation-based research structure to evaluate the impact of experimental variables (including ATP mechanism, various uncertainties, etc.) on the performance of the LED supply chain. The performance indexes used in the study include system cost, fill rate, flow time, and the ratio of rejected orders. Finally, a real LED supply chain is used to demonstrate the research structure. Based on the results of the example, ATPM1 (i.e., less constraints) performs better with respect to the measure of the ratio of rejected orders, while ATPM2 or ATPM3 (i.e., more constraints) performs better with respect to the measure of fill rate or flow time.