應用TOC整體安全保護時間概念於晶圓廠之交期控制

Abstract

交期達成率的高低左右著晶圓代工廠的競爭與生存，是相當重要的一個績效指標。本文主要以現場派工來改善交期的績效。以往發展出的現場派工法則，主要依其生產線上的狀態預測週期時間，求得其完工時間是否會在指定的交期之前完成，以便判斷該給予工件什麼樣的加工優先權，使工件能在預訂的交期之內完成，此做法往往因為對各階段所估計的週期時間太過於保守或保護，使得降低週期時間的努力未能達到先前的預期績效。〝TOC整體安全保護時間〞的觀念為Dr. Goldratt首先提出於專案管理的進度控制 ，TOC整體安全保護時間強調的不是進度的預測，其所強調的是整體安全保護時間是否可以保護整個專案的準時達成。本文將以整體安全保護時間的觀念為基礎，發展出一套保護交期準時達成的現場監控法則，依工件是否可達成交期給予其適當的加工優先權以滿足交期，改善與交期相關之績效。 經由模擬驗證之結果顯示，應用整體安全保護時間之監控法則對於不同派工法則在交期達成率、平均延遲、平均延遲變異及平均延誤的績效都有較佳的表現。

Due-date performance is one of the most important production performance indexes in wafer fabrication industry. This study try to develop a new method of shop flow scheduling for improves missed due-date performance. The traditional methods were addressed on cycle time estimation. Most of those papers use the estimated cycle time to forecast the completion time of the product, and then utilized the part’s slack time to schedule the lot’s priority. Unfortunately, few of those methods used in shop flow successfully. The concept of TOC aggregated time buffer was developed by A. Y. Goldratt in project management. This concept use the aggregated time buffer to protect the whole project’s due date instead of that only consider individual tasks. Therefore, this study aims to develop a new shop floor scheduling method base on the concept of TOC aggregated time buffer. This method is expected to reduce the mean tardiness and tardiness job’s. A simulation model with real world data is also established to examining the performance of the proposed method. The simulation result shows a better performance was obtained for rate of due date commitment, average tardiness, variance of average tardiness and average lateness when the shop floor control rule of the TOC’s aggregated time buffer is applied for different dispatching rules.