Sequencing mixed-model assembly lines: Survey, classification and model critique

Abstract

Manufacturers in a wide range of industries nowadays face the challenge of providing a rich product variety at very low cost. This typically requires the implementation of cost efficient, flexible production systems. Often, so called mixed-model assembly lines are employed, where setup operations are reduced to such an extent that various models of a common base product can be manufactured in intermixed sequences. However, the observed diversity of mixed-model lines makes a thorough sequence planning essential for exploiting the benefits of assembly line production. This paper reviews and discusses the three major planning approaches presented in the literature, mixed-model sequencing, car sequencing and level scheduling, and provides a hierarchical classification scheme to systematically record the academic efforts in each field and to deduce future research issues.

The Car Resequencing Problem with Pull-Off Tables

“…Clearly, the practitioner when deciding on an appropriate buffer dimension has to balance the elementary trade-off between investment cost for pull-off table installation and the gains of additional resequencing flexibility. Especially, the latter effect is hard to quantify, since determining an appropriate optionspecific cost factor for a sequencing rule violation is hardly possible (Boysen, Fliedner, and Scholl 2009). However, our results reveal that the number of pull-off tables to be installed heavily depends on the number M of models to be considered and number T of production cycles.…”

“…On the one hand, future research could approach the car resequencing problem applying different forms of buffer organization, e.g., mixed banks (Spieckermann, Gutenschwager, and Voß 2004). On the other hand, alternative sequencing objectives, like mixed-model sequencing (Boysen, Fliedner, and Scholl 2009) could be modified to cope with limited resequencing flexibility due to a given number of pull-off tables.…”

“…Standard CSP approaches (for an overview see Boysen, Fliedner, and Scholl 2009) assume that a department's production schedule can be fully determined by the planner and no unforeseen events occur. However, those assumptions are not realistic.…”

“…For example, when assembling cars on a mixed-model assembly line, car bodies should be scheduled in such a way that the work load of the workforce has no peaks by avoiding the cumulated succession of cars requiring work-intensive options. The car sequencing problem (CSP), which was developed by Parello, Kabat, and Wos (1986) and received wide attention both in research and practical application (Solnon, Cung, Nguyen, and Artigues 2008;Boysen, Fliedner, and Scholl 2009), returns a production schedule where work overload is avoided or minimized. It uses H o : N o -sequencing rules, which restrict the maximum occurrence of a work-intensive option o to at most H o out of N o successive car models launched down the line.…”

Time-Based Conditions for Synchronized Procurement in Douki Seisan

“…Following the notation in Boysen et al, (2009) the planning horizon is divided into T production cycles (with t = 1; . .…”