Storage allocation strategies and assignment rules for travel time minimization in an Order Picking System

Order picking is the process of retrieving products from a storage area in response to a specific customer request. Advanced approaches to improve order picking efficiency can significantly reduce customer response time in a supply chain system, decrease the overall logistic costs and improve customer service level. In particular, the allocation strategy deals with the determination of the best fraction of storage volume for each SKU, while the storage assignment problem deals with the assignment of products to storage locations: which is the best amount of space to each Stock Keeping Unit – SKU? Which is the best location for the generic product? Bartholdi and Hackman (2007) discuss about the first issue in order to reduce the number of restocks in a fast pick (forward) and bulk storage (reserve) picking system. The aim of this study is to develop and apply a systematic procedure for the minimization of pickers traveling time and distance in a forward – reserve picker to part order picking system in accordance with different strategies for the determination of the storage space in the fast (primary) pick area and different products assignment rules. The proposed procedure, models and tools are applied to a significant case study, and the obtained results coming from a what – if analysis area compared in order to identify effective guidelines for practitioners and logistic managers of industry.