傳統經濟製造批量模式上，一般假設生產製程是完美的，且無不良品產生，但實際 上不良品的產生是無法避免的。當生產製程出現不良品且必須重製時，將會增加不良品 的重製成本。產品維修保證已成爲廠商不可或缺的售後服務之一，也增加了產品的保證 成本，故有學者將生產與售後維修一併納入考量。本文假設不完美生產系統具退化情 形，並服從指數分配，考量在期望總成本最小的原則下，建立一個數學模式，並透過對 該模式求解，找出最佳生產期間，發現在單位總成本最小化的目標函數下，生產期間有 唯一的最佳解。最後，以數値範例進行驗證，發現模式加入重製成本後，最佳生產期間 和單位總成本均明顯增加，可見得重製成本的重要，希望提供國軍生產製造中心與民間 製造商擬訂生產期間之決策參考。

In the past, those scholars who made a study of the optimal cycle time often presumed that the production process was perfect which implied the defective product would not be produced. However, the production of the defective product was unavoidable. When the defective products appear, they must be reworked in the production process, the rework cost increases from this. The repair warranty of the products was one of manufacturer's indispensable after-sale services, but the warranty cost increases at the same time. In the past years, the question of production and warranty had already jointly in scholar's discussion. In this paper, we assume that the failure rate of the imperfect production system follows an exponential distribution. A mathematical model is developed to determine the optimal production run length with the expected minimum cost per item. Finally, a numerical example is given to illustrate the results, and offer the administrators of Materiel Production and Manufacturing Center or civil industries making decision.