Optimal preventive maintenance and replacement schedules with variable improvement factor

Purpose – This paper seeks to develop and present a new mathematical formulation to determine the optimal preventive maintenance and replacement schedule of a system.Design/methodology/approach – The paper divides the maintenance‐planning horizon into discrete and equally‐sized intervals and in each period decide on one of three possible actions: maintain the system, replace the system, or do nothing. Each decision carries a specific cost and affects the failure pattern of the system. The paper models the cases of minimizing total cost subject to a constraint on system reliability, and maximizing the system reliability subject to a budgetary constraint on total cost. The paper presents a new mathematical function to model an improvement factor based on the ratio of maintenance and repair costs, and show how it outperforms fixed improvement factor models by analyzing the effectiveness in terms of cost and reliability of the system.Findings – Optimal decisions in each period over a planning horizon are soug...