A review of cost and profit oriented line design and balancing problems and solution approaches

Abstract

This review paper presents the state of the art on the problems, approaches and analytical models for assembly and transfer line design and balancing that addresses explicitly cost and profit oriented objectives. The discussions aim to facilitate identifying open problems and research areas that have wide practical applications and that necessitate further investigations. Moreover, they might serve as a foundation for developing decision support systems (DSS) that aid managers in planning and designing profitable or cost efficient assembly and transfer lines.

Introduction

Assembly and transfer lines contain serially located workstations in which the operations are continuously carried out. They have been installed in various industries such as the automotive, home appliance or electronics, where the major goal is to efficiently produce and deliver large amounts of standardized products. As a consequence of efficiency pursuit of these industries, modeling and solving line balancing problems have gained importance. A rich assembly and transfer line balancing literature, which covers numerous optimization problems, emerged.

These problems require development of capacity or cost-based modeling and use of effective solution techniques. For more details on line balancing problems, modeling and solution methods, we refer to the survey papers, such as Ghosh and Gagnon (1989), Erel and Sarin (1998), Rekiek, Dolgui, Delchambre, and Bratcu (2002), Becker and Scholl (2006), Scholl and Becker (2006), Boysen, Fliedner, and Scholl (2008a) and Rashid, Hutabarat, and Tiwari (2012). We also cite Boysen, Fliedner, and Scholl (2007) and Battaia and Dolgui (2013) for classification of the problems.

Although these interesting surveys present a broad range of line balancing problems and methods, they do not provide an in-depth analysis of some important branches of line design and balancing literature. This lack is noticeable for cost and profit based models, despite their recognized importance (see, e.g., Falkenauer, 2005). One possible explanation could be the scarcity (at the time these surveys were written) of publications on this topic, in comparison with other branches which had produced an abundant literature. Even though capacity oriented approach is more common in the literature, models where costs and profits are explicitly calculated and optimized in all phases of product life cycle are taking attention of researchers. Studies on this field have been rapidly increasing recently (almost half of the papers cited in this review were published during the last 8 years).

We concentrate on this particular branch and provide an in-depth analysis of cost and profit based line design and balancing models. Such a detailed study allows us to investigate the use of optimization tools in the design of production facilities, to explain their needs in planning and control of activities, from product and process design to recycling, and to clarify their characteristics and importance for product life cycle management (PLM).

It should also be noted that most of the models presented in this survey require various data on costs in order to produce cost-efficient line balance. It might not be always possible to have reliable cost figures at the point in time line balancing is performed. Thus, often researchers fall back on simple performance criteria of the capacited models, which are available, e.g., the number of stations or the cycle time. Moreover, under specific premises some simple line balancing problems also minimize costs, e.g., the capacity oriented Simply Assembly Line Balancing Problem of type 1 (SALBP-1) leads to a cost minimum, whenever any station costs the same. Also minimizing the cycle time for the capacity oriented Simply Assembly Line Balancing Problem of type 2 (SALBP-2) could maximize profit in specific circumstances.

However, nowadays many companies can reach to accurate data, they are more and more seeking to use this information and generate more effective designs. We also note that cost and profit based models are usually used at advanced stages of the design process. At the initial stages, a set of possible configurations is selected by using capacity oriented models. Cost- or profit- oriented approach is employed afterwards.

Considering the increase in the number of publications on cost- and profit-oriented models, we believe that it has become necessary to structure this field and develop a more detailed classification. Moreover, we make a concerted effort to present research gaps and explicitly list promising areas. We discuss the possible research perspectives. The discussion could help to identify open problems and research areas that have wide practical applications and need further investigation.

This article is an expanded and improved version of the paper presented at the 19th World Congress of the International Federation of Automatic Control in Cape Town, South Africa (Hazir, Delorme, & Dolgui, 2014).

Section 2 will introduce the classification and then review and discuss the main publications in each class. Section 3 will present a synthesis of this review and provide some discussions on future research directions.