Throughput and inventory analysis of a flexible machine for different maintenance policies

Abstract

In this study, a manufacturing shop oor with two part types is examined and the impacts of di erent production and maintenance policies on the average throughput and average bu er levels are compared. Basically the comparisons are between a exible machine with two di erent maintenance strategies and two independent ordinary machines, which are capable of producing only one type of product. A two-machineone- bu er(2M1B) line is modelled as a Discrete State Continuous Time Markov Chain for two di erent layouts. First layout includes a exible machine which is followed by a reliable assembly machine. Two types of parts, produced by the exible machine, are assembled at the second workstation. In this layout, two di erent maintenance policies will be applied. First one is called Repair Together Policy; when a tool breaks down, the machine is not stopped and production goes on with the other part type until both tools are down. At that point, both tools are repaired together. Second maintenance policy is called Stop and Repair Policy; whenever a tool breaks down, the machine is stopped and that tool is repaired. Production goes on from the same point after the repair. The other layout to be used includes two independent/ordinary machines that are followed by a reliable assembly machine. After Markov anlaysis of the single machine cases for each system and maintenance policy, 2M1B lines are examined. Exact solutions are found by a software program using balance equations and used for comparison of the systems and maintenance policies. Results are investigated from a managerial point of view trying to decide which system and maintenance policy is better in which parameter set of the machines.