Warehouse Design For Assembly Line Parts Feeding In Case Of Kitting And Different Parts Attributes

The warehouse picking activity is a complex problem. In case of assembled products, the assembly lines parts feeding problem is strongly related to the picking problem. In case of kitting feeding policy, where each part is picked to create kits for each product to assemble, the picking activities are significantly high. The basic element of differentiation of a such picking problem is that to each kit typically correspond a certain assembly station/area. Different parts categories, especially in case of medium-large assembled products, can be part of the same kit: small pickable parts (SPP), large parts but pickable by an operator (LPP), large parts not pickable by an operator but pickable using a proper equipment (NPP). In a such configuration the warehouse facilities should be different for each part category, i.e. racks for SPP, traditional shelving for LPP, non-shelving for NPP. Because of about half of the total picking time is related to the picker travel activity, in order to minimize the picking time each aisle should contain all these three warehouse facilities typologies and the parts for the same kit. In this paper, a two-level warehouse parts location approach is proposed. Once assigned to each part a proper stock keeping unit in the warehouse and the related attribute, the first step clusters parts into part families depending on in which zone of the assembly line and kit they are used. In the second step an optimization model is proposed to determine the optimal location of parts minimizing the total picking distance with the aim of storing the same cluster in the same aisle, considering that SPP, LPP, NPP aisle dimension is fixed for the whole warehouse. A case study from an harvesting producer company is detailed reported demonstrating the applicability and the practical implication of the research.