Lockout/tagout and operational risks in the production control of a transfer line with passive redundancy

This paper presents an analytical model for the joint determination of optimal production and occupational safety for a failure prone manufacturing system consisting of three machines (two machines as passive redundancy and a third machine in series with the previous ones) producing one type of part. These machines are subject to breakdowns and repairs and the control problem is subject to non-negative constraints on work-in-processes (WIP). The decision variables are the production rate of two main machines and a standby machine. The decision variables influence the WIP levels, the inventory levels and the system's capacity. The system capacity is assumed to be described by a finite state Markov chain. The aim of this paper is to minimize the cost of WIP, inventory while respecting occupational safety. The proposed approach is based on the combination of analytical formalism, simulation modeling, design of experiments and response surface methodology to optimize a transfer line in passive redundancy producing one part type. The usefulness of the proposed approach is illustrated through a numerical example.