從設備投資之回收年限的觀點建立自動化物料搬運系統的評估方法

The development of an evaluation method based on the investment return for AMHS in a semiconductor plant

鄭暉達(Hui-Ta Cheng)

指導教授 ： 謝淑華

國立臺灣大學/工學院/機械工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.02164

摘要

由於12吋晶圓的引進，非生產設備的自動化物料搬運系統將全面導入晶圓製造廠中。針對生產設備之效益評估，一般皆以投資報酬率為主要訴求，因此回收年限就成為其評估的重要指標。至於非生產設備之自動化物料搬運系統，則大都以搬運效率為評估的依據。
本研究擬從回收年限的角度，來探討與評估比較不同設計的自動化物料搬運系統，進而提供投資者一套評估的準則。本研究將先以Little’s Law的觀念，將非生產設備之系統效益區分為產能提升及線上在製品庫存降低兩種情形。再以限制理論為基礎提出新的成本概念，並經由此概念將系統效益變化加以資金化，最終再以裝設成本及資金化後之效益變化來估算其回收年限。透過本研究所提出之評估方法，期投資者能對於晶圓廠中自動化物料搬運系統於整體效益的提昇有更深一層的認識。

關鍵字

自動化物料搬運系統 ； 回收年限 ； Little’s Law ； 限制理論

並列摘要

Because of the advent of 12-inch semiconductor wafers, the automated material handling system (AMHS) becomes a necessary investment to the industry. The main evaluation methods for most of production equipments are normally based on the investment return. For those non-productivity equipment investments, the investment returns are difficult to estimate since they do not produce products. Therefore, the evaluations of the AMHS are mostly focused on the minimization of the total traveling distance. However, the shortest traveling distance does not guarantee the best efficiency. Of course, it does not lead to the best investment return.

The main purpose of this study intends to evaluate an AMHS from the investment return viewpoint. This study includes two parts. In part I, by adopting the concept of the Little's law, the system efficiency due to the installation of an AMHS can be quantified. The resulting efficiency can either be from the increase of the throughput, or the decrease of the WIP inventory. The former makes extra sale profit, and the latter saves the WIP inventory cost. In part II, based on the theory of constraints (TOC), TOC product costing and profit estimation formulations are established. The investment return years can then be estimated by dividing the sale extra profit to the investment for the case of the throughput increase, or by dividing the saving inventory cost to the investment for the case of the WIP inventory decrease. For the purpose of demonstrating the proposed method, a specified simulation case is performed and the years of returns are estimated one by one for different market prospects at last.

並列關鍵字

an automated material handling system ； investment return ； Little’s Law ； theory of constraints

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