在現代的工廠中，在製品經常是被拿來衡量工廠製造能力的績效指標之一，公司如何在有限的資源及需求快速變化的背景下做好在製品管控將是重要的課題。制訂標準且合理的在製品數量除了可以降低空間利用率及存貨成本外，更可以減少因生產過程中異常狀況發生時所帶來的附加成本。
　　本文選定一家EMS工廠作為本次的研究對象，並以個案研究的方式進行。本研究主要探討於相同的生產條件下，推式生產(Push)與CONWIP(Constant Work In Process)生產兩種模式的生產績效，並透過FlexSim系統模擬進行數據蒐集，以在製品數量、產出率(TH)、產品週期時間(CT)等指標進行改善前後效益的比較。同時探討人員作業不穩定的情況下，須達成最大產能所對應到的最佳的在製品數量。

In modern factories, WIP (Work In Process) is often one of the performance indicators used to measure the manufacturing capacity of factories. How to do WIP management and control under the background of limited resources and rapid changes in demand will be an important issue. In addition to reducing space utilization and inventory costs, it can also reduce additional costs caused by abnormal conditions in the production process through setting Set standard and reasonable WIP.
　　This article selects an EMS factory as the object of this study, and conducts it in the form of a case study. This research mainly discusses the production performance of the two modes of push production and CONWIP(Constant Work In Process) production under the same production conditions, and collects data through the simulation of the FlexSim system. WIP, Throughput (TH), Product Cycle Time (CT) and other indicators benefits are compared before and after improvement. At the same time, it discusses the optimal number of WIPs to achieve the maximum capacity under the condition of unstable personnel operations.

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