Publications in peer-reviewed journals
• Schmid, N.A., Lim`ere, V., Raa. B. (2021) Mixed model assembly line feeding with discrete location assignments and variable station space, Omega - The international Journal of Management Science, 102.
• Schmid, N.A., Lim`ere, V. (2019) A classification of tactical assembly line feeding problems, International Journal of Production Research, 57(24), pp. 7586–7609.
Publications in peer-reviewed conference proceedings
• Lim`ere, V., Popelier, L., Schmid, N.A. (2021) Balancing disassembly lines under considera-tion of tool requirements and limited space, 17th IFAC Symposium on Informaconsidera-tion Control Problems in Manufacturing
• Schmid, N.A., Wencang, B., Derhami, S., Montreuil, B., Lim`ere, V. (2021) Optimizing kitting cells in mixed-model assembly lines, 17th IFAC Symposium on Information Control Problems in Manufacturing
• Schmid, N.A., Lim`ere, V. Raa, B. (2018) Modeling variable space in assembly line feeding, IFAC-PapersOnLine 51 (11), 164-169.
• Wijnant, H. Schmid, N.A. Lim`ere, V. (2018) The influence of line balancing on line feeding for mixed-model assembly lines, Proceedings of the 32nd annual European Simulation and Modelling Conference, pp. 106–111.
Working paper
• Schmid, N.A., Lim`ere, V., The impact of spatial considerations on assembly line efficiency.
• Schmid, N.A., Montreuil, B., Lim`ere, V., Integrating assembly line feeding and balancing optimization for improved decision making.
Presentations at (inter-)national conferences
• A Decomposition Scheme For Integrated Planning Of An Assembly System, coauthors:
Montreuil, B., Lim`ere, V., INFORMS Annual Meeting 2020, 11/2020, Virtual Conference, USA.
• Simultaneously optimizing assembly line feeding and assembly line balancing, coauthors:
Montreuil, B., Lim`ere, V., 34th annual conference of the Belgian Operational Research Society, 01/2020, Lille, France.
• Incorporating assembly line balancing into assembly line feeding decision making, coau-thors: Montreuil, B., Lim`ere, V., INFORMS Annual Meeting, 10/2019, Seattle, USA.
• Improving the solvability of time and space constrained assembly line balancing problems type E, coauthor: Lim`ere, V., Canadian Operational Research Society 61st Annual Con-ference, 05/2019, Saskatoon, Canada.
• Modeling variable space in assembly line feeding, coauthors: Lim`ere, V., Raa, B., 16th IFAC Symposium on Information Control Problems in Manufacturing, 06/2018, Bergamo, Italy.
• Optimizing line feeding under consideration of variable space constraints for mixed-model assembly lines, coauthor: Lim`ere, V., at: 32nd annual conference of the Belgian Operational Research Society, 02/2017, Li´ege, Belgium.
• Line feeding with variable space constraints for mixed-model assembly lines, coauthor:
Lim`ere, V., International Conference on optimization and decision sciences, 09/2017, Sor-rento, Italy.
• The assembly line feeding problem: classification and literature review, coauthor: Lim`ere, V., 31st annual conference of the Belgian Operational Research Society, 02/2017, Brussels, Belgium.
Funding
I acknowledge this doctoral research project’s support by the ‘Bijzonder Onderzoeksfons’ of Ghent University under grant number BOF.STA.2016.0023.01 and by the ‘Fonds Wetenschap-pelijk Onderzoek – Vlaanderen’ under grant number FWO18/ASP/198. The National Bank of Belgium also supported this project.
A classification of tactical assembly line feeding 2
problems
“In considering any new subject, there is frequently a tendency, first, to overrate what we find to be already interesting or remarkable; and, secondly, by a sort of natural reaction, to undervalue the true state of the case, when we do discover that our notions have surpassed those that were really tenable.”
Ada Lovelace
2.1 Introduction
The manufacturing industry is progressively facing more competition, resulting in a wide variety of highly functional products. Consequently, single manufacturing firms produce many very complex product models with many functionalities in an enormous number of mass-customized variants, as discussed above. This product complexity may be underlined by looking at a case study done at a truck manufacturing company. The company needed to handle the astonishing amount of 8,000 to 9,000 parts each day to produce just around 15 trucks (Lim`ere et al., 2012).
These numbers even exclude small parts like nuts and bolts, and therefore, clearly illustrate that assembly lines need to be fed with an enormous amount of parts already and that this number will likely increase in the future.
Assembly line feeding, describing the provision of parts for assembly, can be performed in different ways by storing all parts near the assembly line or pre-processing parts and delivering them when needed (Sali and Sahin, 2016). The assembly line feeding problem (ALFP), formally defined in this study, studies how parts should be provided for assembly by identifying the optimal provision method for every part. Obviously, deciding on the way how to provide parts not only has an impact on the used load carrier or quantities fed, but also on the design of the feeding system with respect to transportation and preparation processes (Lim`ere et al., 2012). Therefore, the design of feeding systems is part of the assembly line feeding problem if it is not predetermined.
Hence, the problem under investigation is a complex task affected by many different aspects and decisions. We will show that some of these aspects are already researched. However, at the same time, there are still numerous questions unanswered, and literature integrating additional aspects, such as the selection of vehicles or the number of storage facilities, is relatively scarce.
As we observed within this review, the number of scientific scholarly papers on issues assembly line feeding problem is increasing. One can assume that this increase is due to both, a rising in-terest of researchers but also the necessity of decision support systems in practice. This practical need for decision support systems has specifically been observed by the authors of this article during company visits. Feeding decisions were either loosely based on rules of thumb, without evaluation of these rules, or even taken without any logical structure.
As the amount of literature increases, effort for scientists to review literature and delimit their work also increases. In addition, not understanding focus and scope of previous research well might result in less distinct and value adding research. Theoretical insights may also be used less often in practice if industrial problems are not encountered in literature, either because they are not yet explored or due to unclear or inconsistent notations and low visibility.
Thus, this study aims at providing knowledge on line feeding processes and at categorizing different assembly line feeding problems, by means of a classification framework. We aim to promote purposeful research, as well as to help practitioners detecting research fitting their practical needs.
The rising interest in the field of line feeding has already motivated Kilic and Durmusoglu (2015) to review the literature. However, their focus is on the characteristics of line feeding policies depicting their advantages and disadvantages and they do not clearly delimit tactical
and operational issues. The present review, instead, is more process-oriented and includes mostly tactical decisions such as layout or transportation mode decisions. Moreover, a classification for existing and future work is provided and a list of research opportunities is given. Another review is done by Boysen et al. (2015) focusing on multiple operational decisions like routing, loading or scheduling aspects within the automotive industry and organizes these along the material flow.
However, the present review does not focus on single operational aspects but considers assembly line feeding as a holistic decision process which, in practice, is followed or supplemented by operational decision making. Furthermore, in contrast to Boysen et al. (2015), the field of application is not limited to the automotive industry.
The remainder of this chapter is organized as follows. In the following section, the scope of the review is defined to underline the importance of the feeding problem and delimit it from general logistical in-house problems or even inter-organizational logistics. Next, in the third section, the classification scheme for the problem is proposed and described. Within the subsequent section, existing literature on the actual ALFP is classified. Section 2.5 points out open research fields and new research opportunities. In the final section, the chapter is shortly summarized.