Contribution to optimization of preventive replacement

The paper presents a method for determining the optimal interval for preventive maintenance/replacement using either an age-based or diagnostic-based renewal strategy. For the case of a finite-time horizon, for which the computations are complicated, a simple formula is proposed for modifying the commonly used inifinite-time solution so that it gives a good approximation to the exact finite-time solution. Examples demonstrate that the method is sufficiently accurate and simple in practice for typical engineering components with Weibull life distributions and for a reasonable range of the cost factor (ratio of unit corrective to unit preventive maintenance costs). This paper investigates the problem of the accuracy of the results compared to the exact, finite-time solution for a selected matrix of time-to failure Weibull shape parameters and cost factors commonly occurring in technical practice. Applications offer substantial benefits to both manufacturer and user of technical equipment.