Batch construction heuristics and storage assignment strategies for walk/ride and pick systems

The retrieval of items from storage is a chore faced by virtually every business concern. Walk/ride and pick systems are a popular method for performing this chore in many applications. When retrieval requests consist of multiple items, order pickers must travel to numerous storage locations to complete each order. When these requests are made in sufficient volume, a method of order retrieval known as batch picking is often used. Batch picking is a popular approach in the mail-order industry and is employed in industrial settings such as tool cribs and in warehouses, which service assembly line operations. Batch construction heuristics are developed and tested under three strategies for assigning storage space to individual items that have been suggested in the literature. Our results are derived from the simulation of a single hypothetical warehouse model. Specifically, we employ a model that is square in travel distance and assume the walk and pick method of order retrieval with sequential one-way travel. Sensitivity analysis is performed on workforce level and batch size. Our results indicate that the methods used for constructing batches of orders and for assigning storage space to individual items can significantly impact order retrieval efforts in warehouses of this type.