製造系統之經濟改善－由失效模式與系統動力觀點

如何避免製程失效是一項重要的課題，然而製程改善需要成本的投入，如何選擇成本效益最佳化的改善方案，是有效提升製程良率的關鍵。本研究探討如何以系統思維建立失效項目及其改善效益之評估，其目的在於分析製造系統失效項目及評估其導致的損失，並提供經濟的改善方案。本研究方法採用失效模式與效應分析(FMEA)進行分析，找出潛在的失效模式，及可能的後果；再應用系統動力學結合改善項目，以預測該系統之『動態』改善成果。其步驟：一、分析製造流程；二、進行失效模式與效應分析；三、建立系統動力模型；四、模擬與分析現況；五、建立改善項目；六、擬定改善方案與遴選改善項目。本研究以LED封裝為應用案例，運用FMEA表建立失效項目，再由系統動力模型模擬得知失效損失。再考量改善項目之可行性，由改善後的動力模型計算其效益，以選擇最經濟的改善方案。本研究結合失效模式、系統動力行為與改善效益分析，提供一個系統化的改善方法，在提升製程良率上，有相當的助益。

關鍵字

製造系統；失效模式與效應分析；系統動力學；失效損失；經濟效益

並列摘要

Avoiding process failures needs investment and how to build a cost-effective improvement program is a key to the success of the quality. This study attempts to find out the failure mode in a manufacturing process and try to improve its performance in a systematic and cost-effective way. A method uses the Failure Mode and Effect Analysis (FMEA) and system dynamics to identify potential failures and predict the operating results. The method consists of six steps: (1) Analyze manufacturing process; (2) Proceed Failure Mode and Effect Analysis (FMEA); (3) Build system dynamic model; (4) Analyze the current loss due to failures; 5. Establish improvement sub-programs; and 6. Chose objective and select the best combination of sub-programs. The method is applied to an LED packaging company for demonstration. The defect items and related failures are built via FMEA table. Based on the manufacturing process, an iThink dynamic model is built for simulation to investigate the failure loss of the current process. Potential sub-programs could be established to avoid failures. After implanting sub-programs into the previous model, loss recovery could be evaluated. Based on rate of return, the most economical program can be formed. The method, integrating FMEA and system dynamics, leads to a good assessment of the improving program from the economic perspective. The improvement program of the LED packaging process demonstrates the method’s effectiveness.