隨著科技日新月異，設備的保證契約成爲賣方的行銷策略之一。本論文硏究具免費維修保 固的生產設備之最佳置換時程對利潤之影響。對於具有免費維修保固之設備，當設備於免費維 修保固期內發生故障，則賣方(製造商)必須負擔維修成本，買方需負擔設備因故障而停止生產 所帶來的損失成本。然而，當設備故障發生於免費維修保固期後，則買方需負擔設備的維修成 本與故障停止生產的損失成本。本論文以買方爲立場，在設備故障率隨時間遞增的情況下，建 構出三種生產設備保固期長度與置換時程的期望總利潤模式並尋求設備的最佳置換時程，最後 以數値範例分析說明在有限時程下，設備的置換時程對總利潤的影響。

This study investigates the influences of optimal replacement time for the production of equipment for profit. For the products with free-repair warranties (FRW), when the equipment fails within the FRW, it is corrected using minimal repair without cost to the buyer. Fallowing FRW, any failure of the equipment incurs a fixed repair cost to the buyer. However, each failure incurs a fixed downtime cost to the buyer. Under this maintenance scheme, the replacement of the production equipment is investigated for two separate cases: before FRW and following FRW. Next, three profit models using a buyer’s perspective are derived, and the optimal replacement time is obtained, features of the proposed optimal replacement time.