塑膠閥類是資本不太大而相對人力密集的利基型產業。對塑膠閥製造商而言，公司的產品有數千種，每一種產品的製造流程，零組件也大多不同，所接訂單包含各式各樣的產品，導致資源及產能分配的工作非常複雜，個案公司現有的生產管理部門無法在這種狀況下將生產管理工作做的很好，訂單交期經常被延, 導致客戶滿意度越來越低，將導致個案公司長期發展有不利的影響，為改善這種現象，因而做此研究。不同於傳統生產規劃與派工法則的設計，限制驅導式現場排程與管理技術(DBR)在工廠現有的環境或機台佈置下，考量整體工廠運作效能，依受限產能(瓶頸)的需求來導引全廠之物流與運作，而降低了非受限產能工作站的排程或派工的資源分配決策問題。因此，本研究目的在針對塑膠閥製造商在派工決策所面臨的生產管理的問題，從整體生產系統的設計觀點出發，應用DBR，重新設計派工決策，以達到提高設備的使用率、降低呆滯料及總庫存量、提高交貨準確率之目的。在此主要目的之下，本研究具以下次目標：從整體系統觀點，探討塑膠閥現有製程(派工)方法的問題；發展以DBR為基礎的塑膠閥產品的派工法則；建立數量化模式，透過模擬，比較與分析不同派工法則下塑膠閥產品製造之績效。本研究發現DBR的生產模式搭配依比例分配產能，可讓未交貨訂單及總存貨成本比現行的生產模式有更佳的表現。透過進一步的測試，本研究也發現在此組合下，2倍訂單量的緩衝有較好的表現，過高或過低的緩衝大小之設計，皆有可能造成交貨時間拉長，及存貨成本提高的狀況。建議後續研究可以進一步以更系統化的方式找出緩衝大小的設定規則。 Plastic valve is a niche, smaller capital and labor-intensive industry. Plastic valve makers provide a great variety of products and the production process and parts for each product are different. Production management is challenging for plastic valve makers to increase the utilization rate of equipment, reduce the quantity of obsolete materials and total inventory reduced and increase on-time delivery rate. In practice, a lot of order can not be delivered on time and customer satisfaction is getting lower and lower. In long term, bad production management may harm the growth.Accordingly, this paper is aimed to explore and evaluate the performance of different dispatching rules in different production environment of plastic valves. While dispatching rules impact directly on capacity utilization rate and the number of on-time delivery orders, the design of production environment sets the planned production requirements, namely, the input of the dispatching rules, and thus have may have a greater impact the production performance. As to dispatching rules, this paper considers two different dispatching rules. One dispatching rule proportionally dispatches machine capacity to different task according to their production requirements. The dispatching rule sets the order fulfillment in the first priority and dispatches capacity to production requirements that is closer to the final products in the production processs. Two different environments are discussed in this paper. One is the well-known Material Requirement Planning (MRP) and the other is the Drum-Buffer-Rope (DBR) mechanism that is based on Theory of Constraints (TOC). Different from MRP-based production environment that is common in plastic valve manufacturing, DBR considers overall performance of facility to adjust operation according to capacity requirement of bottleneck in existing environment and equipments layout. With a case as an illustrative case, this study applies the system dynamics approach to build up a simulation model to evaluate how different dispatching rules in different product environment may perform. Some suggestions regarding to production planning are further proposed. The result is the performance in DBR-based manufacturing systems with dispatching rule that is based on proportional capacity distribution is better than other portfolios.
