A New Look at the Bowl Phenomenon

Abstract

ABSTRACT. An interesting empirical result in the assembly line literature states that slightly unbalanced assembly lines (in the format of a bowl -with central stations less loaded than the external ones) present higher throughputs than perfectly balanced ones. This effect is known as the bowl phenomenon.In this study, we analyze the presence of this phenomenon in assembly lines with integer task times. For this purpose, we modify existing models for the simple assembly line balancing problem and assembly line worker assignment and balancing problem in order to generate configurations exhibiting the desired format. These configurations are implemented in a stochastic simulation model, which is run for a large set of recently introduced instances. The obtained results are analyzed and the findings obtained here indicate, for the first time, the existence of the bowl phenomenon in a large set of configurations (corresponding to the wide range of instances tested) and also the possibility of reproducing such phenomenon in lines with a heterogeneous workforce.

Consideration of workers’ differences in production systems modelling and design: State of the art and directions for future research

“…It should be noted that studies that considered workers' differences in terms of disability were also found. Since the pioneering study by Miralles et al (2007), the integration of workers with disabilities in assembly line balancing and worker assignment has received considerable attention among researchers (Araújo, Costa, and Miralles 2012;Borba and Ritt 2014;Castellucci and Costa 2015;Cortez and Costa 2015), including variants of such topic, such as disabled-friendly job rotation objectives (Costa and Miralles 2009), line layouts (Araújo, Costa, and Miralles 2015) and more general industrial settings, extrapolating data from sheltered work centres for the disabled (Moreira, Miralles, and Costa 2015). However, we did not include this topic in our research keywords as our objective was to study the general framework of workers' differences.…”