Industrial-based time performance of assembly cell operators: Impact assessment characterization by discrete-event simulation

Abstract

Assembly cells often depend on the human elements when an extended automation is not (economically, even if technologically) possible. The workers' natural variability is impossible to avoid in a manual assembly system. Usually when simulating an assembly system, a given task time distribution is assumed as the representation of the workers time performance. Workers have variations in their performance that can incur in the shifting of this distribution relative to the expected performance time distribution, as well as in the widening of this distribution, by the increase or decrease of dispersion. This paper presents a discrete event simulation model of an assembly system where the operators have different time distributions, aiming to assess their influence in the overall system performance. Those time distributions were obtained in industrial context, in a previous study, by observing workers in an assembly cell, so representing real performance of workers. The results indicate that the worst performing worker will "pace" the output system performance to a slower rhythm, while better performances of a single worker will only increase very slightly the system productivity.