Joint Maintenance and Spare Parts Inventory Planning (Case Study : Pre – Paint Shuttle Robot of an Automotive Company)

Carrying out maintenance planning for machine tools is one of the critical factors in reducing operating costs. Inventory management is a key element on the performance of the maintenance policy. Through current research, an integrated inventory control of spare parts and maintenance scheduling is proposed to determine the maximum inventory level as well replenishment cycle (S,T), along with the determination of the optimal preventive maintenance period. The total cost associated with the maintenance system, such as the cost of periodical and emergency orders and the costs of inspections and repairs are minimized via the model objective function. To illustrate the capability and performance of the model, the results of applying the model into a case study is reported in an automotive pre-paint line for determining inventory control policies of a critical item. In addition, in order to analyze the stability of the results, the sensitivity of the variables to the changes in input parameters has been investigated. Based on the results, the total cost is affected by the failure rate, the lead time period, and the cost of replacing defective items. In this regard, the system is more sensitive to failure rate and the lead time. In the case of constant failure rates, applying the proposed method might be successful.