Functional and Cellular Layouts
Layout problems are usually multiple-objective and ill-structured problems. The main objective of layout design problem is to find the best arrangement of physical facilities to provide an efficient operation. Sinriech and Tanchoco (1991) pointed out that it is one of the major determinants for the efficiency of the whole system.
Traditionally, the layout design problems are mainly studied from the facility functional layout perspective where facilities are grouped in close physical proximity, but now most common application is to adopt group technology (GT) to identify the similarities in the cell layout design which focused on the efficient processing of products. Some firms have reported that the benefits by adopting GT over traditional functional layouts included reduced work-in-process inventory and increased managerial control since parts and machines are identified to the groups. For example, by using 24 model-based experimentation, Johnson and wemmerlöv (1996) pointed out why cellular layouts outperform their functional counterparts. Later, the same authors reported an average reduction of 61% in throughput times for 27 respondents (Wemmerlöv & Johnson, 1997). More information can be founded in (Agarwal & Sarkis, 1998; Assad, Kramer, & Kaku, 2003). In addition, Pattanaik and Sharma (2009) reported that cellular layout helps to achieve many of the objectives of lean manufacturing such as reducing the waiting times and improving the works-in-progress.