The published research has focused primarily on the problem of partitioning among pickers. There are two major types of batching heuristics that attempt to minimize total picking effort and are based on VRP heuristics. A seed algorithm selects initially a single seed order in the batch. More orders are then added according to a route closeness
criterion until no more orders can be added due to a capacity constraint. The capacity constraint can be based on total pick time, number of orders in the batch,
or weight. A savings heuristic starts by assigning each order to a separate batch. The algorithm then iteratively selects a pair of batches to be combined based on the savings of combining them until no more batches can be combined due to the capacity constraint.