設定保護性產能對排程穩健性之影響

Abstract

保護性產能的定義為在非限制資源上，留具比限制資源多出一定數額的多 餘產能，用來保護統計性波動(停機、延遲收料、品質問題等。)。保護性 產能提供非限制資源趕上進度之能力，以確保生產速率與預定完成日期。 本文運用以寬裕為導向之排程法設定保護性產能，並提出保護性產能行動 準則，以辨識並決定：哪些非限制資源需要保護性產能、預留時機、相關 資源如何配合、保護性產能的大小如何決定，以及耗用時機。此方法除了 可以強化排程規劃之穩健性外，並且提供一產能管理方式，在系統不穩定 時，能真正發揮其功能。以寬裕為導向之排程法設定保護性產能，可從三 個層面來因應未預期之干擾事件：（1）第一層面：以排程寬裕時間理念 ，構建具有穩健性之排程規劃。（2）第二層面：以作業多餘寬裕值為指 標，構建優先次序生產控制。（3）第三層面：以保護性產能提供趕工能 力。以寬裕為導向之排程法，提供工件在適時、適量、適地的情況下進行 同步生產，並透過保護性產能行動準則之實踐，在週期時間與在製品量的 控制上都有較優的績效。 According to APICS dictionary, the definition of protective capacity is: "A given amount of extra capacity at non- constraints above the system constraints capacity, used to protect against statistical fluctuation ( breakdowns, late receipts of materials, quality problems, etc.)." That is, the protective capacity provides non-constraints with the ability to "protect" throughput and due date performance.This thesis applies float-time oriented scheduling method to set protective capacity. It can cope with disruptions from three different phases: (1)First phase: using float time to construct a robust schedule; (2)Second phase: deriving the priority order for control, according the float-time indexes; (3)Third phase: using protective capacity to catch up the planned pace, when disruptions occur. Thus, this method not only strengthens the robustness of a schedule, but also offer a way of capacity management that can be really functioned when the system is suffered disruptions.The thesis also proposes the principles of initiator's actions for using the protective capacity. The principles include: How to identify non-constraints that need to set protective capacity? When is needed? How to cooperate the related resources? How to decide the level of protective capacity? And when to exhaust the protective capacity?The simulation results show that better performance is achieved on both the cycle time and the work-in-process level when following the principles of initiator's actions. This is done because that the float-time oriented scheduling method ensures the production of parts at right time, right quantity and right place.