Experimental assessment of the productivity improvement when using U-shaped production cells with variable takt time

Patrick Pujo (1) , Ilham El Khabous (1) , Fouzia Ounnar (1)

1 AMU - Aix Marseille Université

Purpose – The aims of this research is to discuss the benefits of U layout for production cell operating in variable takt time. Different experiments were conducted using benchmarks, in order to highlight the performance gap between a straight cell and a U-cell. Design/methodology/approach – The implementation of the production cell, in U-shaped or in straight line, is optimized through linear programming based on the number of operators. The two corresponding programs, in Mosel language, use the same approach, in order to not introduce defects in the comparison of results. The study used our own datasets and well known academic benchmarks. Findings – A comparison between the obtained takt times, with equivalent operating conditions, in U-cell and straight cell was conducted. A significant increase of the production rate was observed. This increase has often exceeded 10 per cent to reach 32 per cent. All the experiments show that, with the same number of operators, a cell in a U layout is always at least as efficient, in terms of reachable production rates, than an equivalent cell in a linear layout. 96 per cent give an improvement of production rate. Moreover, the dispersion of the U-cell results is weaker, which suggests that the U-layout gives, in more robust manner, better performances. Research limitations/implications – The results were obtained through a study of various academic benchmarks. The results must be validated on industrial situations. Practical implications – This paper will be very useful for researchers and practitioners in order to understand lean implementations and its derived benefits. This paper will allow them evaluating and analysing the expected benefits of the implementation of the production cell in U-shaped (operating in variable takt time). Originality/value – U-Cells constitute an appropriate solution for a layout of any kind of production cells with variable structure. When facing a significant variation in the demand, the response consists in modulating the number of operators assigned to the cell. This study addresses jointly the problem of U-cells layout and the operation in variable takt time.

Mots clés: assembly line balancing; production variable throughput; linear programming for optimization; U-shaped production cell; straight production line

Domaines: Automatique; Recherche opérationnelle [math.OC]; Automatique / Robotique

Patrick Pujo, Ilham El Khabous, Fouzia Ounnar. Experimental assessment of the productivity improvement when using U-shaped production cells with variable takt time. International Journal of Lean Six Sigma, 2015, 6 (1), ⟨10.1108/IJLSS-07-2013-0038⟩. ⟨hal-01201817⟩