Modeling transportation mode selection in the assembly line feeding problem

Feeding mixed model assembly lines with parts is a complex task in an era of mass customization, and therefore it has received increasing academic attention since the last two decades [1]. Making feeding decisions based on an optimization model has been introduced by [2] and is referred to as the assembly line feeding problem (ALFP). Specifically, the ALFP is concerned with the assignment of every part to a line feeding policy, with the goal of minimizing total material handling costs [3]. The major feeding policies comprise line stocking (also known as bulk feeding), boxed-supply, sequencing, stationary and traveling kitting. Each feeding method has its unique procedure of providing parts to the border of line (BoL) from the warehouse, where BoL describes the area designated to store parts at every station. \\ This research studies the ALFP by including transportation mode selection decisions. This idea is previously indicated as an interesting new research direction [3, 4], but it has not yet been approached by an overall optimization model. On the one hand, our model assigns every part to one of all five distinct feeding policies. On the other hand, it allocates transportation modes to carry out the material flows. Three transportation modes are considered: automated guided vehicle (AGV), tow train and forklift. All of these modes have specific characteristics in operation and comprise different investment costs. A quantitative model minimizing operating and investment cost for assembly line feeding is proposed. The proposed mixed integer programming (MIP) model minimizes total material handling costs incurred through four subprocesses: (1) replenishment of the preparation area; (2) preparation; (3) transportation to the line; and (4) usage at the line. The replenishment cost and the transportation cost include for every selected transportation mode an operating cost for the movement of material, and an investment cost for the acquisition of transportation equipment. The proposed model is solved using Gurobi 8.1.0 using artificial datasets. Some preliminary results will be presented. References 1 Bozer, Y. A., and McGinnis, L. F., 1992. Kitting Versus Line Stocking: A Conceptual Framework and a Descriptive Model. International Journal of Production Economics 28 (1): 1–19. 2 Limère, V., van Landeghem, H., Goetschalckx, M., Aghezzaf, E. H., and McGinnis, L. F., 2012. Optimising part feeding in the automotive assembly industry: Deciding between Kitting and Line Stocking. International Journal of Production Research 50 (15): 4046–4060. 3 Schmid, N. A., and Limère, V., 2019. A Classification of Tactical Assembly Line Feeding Problems International Journal of Production Research 57 (24): 7586–7609. 4 Battini, D., Gamberi M., Persona A., and Sgarbossa F. 2015. Part-feeding with Supermarket in Assembly Systems: Transportation Mode Selection Model and Multi-scenario Analysis. Assembly Automation 35 (1): 149–159