In this paper, a forecasting production/maintenance optimization problem has been proposed with a random demand and
single machine M1 on a finite horizon. The function rate of the machine M1 is depending on the production rate for each
period of the forecasting horizon. In order to satisfy the customer, a subcontracting assures the rest of the production
through machine M2 with transportation delay. An analytic formulation of the problem has been proposed using a
sequential computation of the optimal production plan for which an optimal preventive maintenance policy has been calculated
based on minimal repair. Firstly, we find, the optimal production plans of principal and subcontracting machines,
which minimises the total production and inventory cost for the cases without and with returned products under service
level and subcontracting transportation delay. Secondly, we determine a joint effective maintenance policy with the optimal
production plan, which integrates the various constraints for the production rates, the transportation delay and the
returned production deadline. Numerical results are presented to highlight the application of the developed approach and
sensitivity analysis shows the robustness of the model