Abstract
The paper presents two mathematical models for the totals maintenance cost: one from the customer point of view (including the costs for automotive immobilization) and the second one from the manufacturer point of view (providing also the maintenance). For the second model, using the Weibull law to model the reliability we define analytically the maintenance cost depending on the periodicity of preventive activities. Corresponding to the point where the first derivate of maintenance cost with respect to periodicity is zero we emphasized the optimum economic periodicity, that could be solved using a special calculation program designed in Microsoft Excel.
Keywords: reliability, maintenance, periodicity, preventive activity.