Human factor policy testing in the sequencing of manual mixed model assembly lines

In this paper the human resource management in manual mixed model assembly U-lines is considered. The objective is to minimise the total conveyor stoppage time to achieve the full efficiency of the line. A model, that includes effects of the human resource, was developed in order to evaluate human factor policies impact on the optimal solution of this line sequencing problem. Different human resource management policies are introduced to cope with the particular layout of the proposed line. Several examples have been proposed to investigate the effects of line dimensions on the proposed management policies. The examples have been solved through a genetic algorithm. The obtained results confirm the effectiveness of the proposed model on the performance optimisation of the line. Scope and purpose This paper deals with the sequencing problem of a mixed model U-assembly line; in particular, it considers the minimisation of the total line stoppage time as an objective function. In order to improve the assembly line performances and to empathise the impact of the human resource in production environment, several help policies between workers have been analysed. Moreover, in the proposed model, finite values of the workers walking speed have been taken into account: in this way, their influence on the adopted help policies was evaluated. As the proposed problem was demonstrated to be NP-hard, a proper genetic algorithm was developed for its optimisation. An extensive experiment was carried out to determine a proper choice among the adopted help policies.