Mixed model assembly line design in a lean implemented manufacturing industry

In this study, mixed model assembly line is developed for two different models of gloves, formerly assembled on separate lines, in a gloves manufacturing firm where lean principles are implemented, with the aim of minimizing lead time and production cost. As process constraints and precedence relations differ from one model to another, the precedence diagram of mixed model assembly line is designed, combining common processes. The skill level of the workers in terms of i) ability to perform a specific task, and ii) time taken to perform a specific task by a specific category worker is also considered while developing a mixed model from individual models. Largest candidate rule has been employed to verify line balancing. The proposed mixed model assembly line was then validated using ARENA simulation software. The performance of proposed mixed model was analysed by comparing it with previously existing set-up in terms of production rate, savings and total cost as well. The comparison analyses were further extended to determine unit and monthly production costs. The results show that the implementation of the model proposed provides substantial improvements in: production rate, production cost, set-up time, waste reduction. Furthermore, this model facilitates successful implementation of lean manufacturing and sustainability through improvements in terms of waste reduction.