Profit Maximization by Integrating Production Planning, Maintenance Scheduling, Quality Aspects and Sale Decisions

The objective of this paper is to improve decision systems by integrating production and sales planning with preventive maintenance scheduling taking into account quality aspects of the production system. The concept of age based imperfect maintenance with multiple PM levels and multi-state machine is taken into account. Reduction in the age of machine corresponds to the cost of scheduled PM and also, the cost of machine restoration is linked to the delay in detecting deteriorated condition. In this paper, the mathematical model of the problem and related formulations are presented and evaluation of the various cost components and interacting factors as well as the different aspects of the model complexity are explained. The objective is to maximize total profit. Total cost of the system is the sum of production, inventory, backorder, and set up cost as well as the cost of corrective and preventive maintenance and the income is acquired by selling perfect and imperfect products in different prices. A numerical example is presented and sensitivity of the model to multiple parameters is tested. Based on the results obtained from solving several problems, integrated approach shows between 0.5 to 20 percent improvements compared to the disintegrated models. Such level of increase in the total profit especially in large companies demonstrates the importance of integration.