Zone picking involves combining groups of customer orders into a master batch, so that multiple orders are picked at the same time. Doing so vastly reduces the travel time required to pick goods for orders. Inventory pickers then forward their picked items to a central location in the warehouse, where the items are separated and matched to specific customer orders. Not only does this approach reduce travel time, but it also reduces the number of inventory transactions to be recorded, since picks are being conducted for multiple units at the same time.
Zone picking creates the largest number of efficiencies when there are many customer orders, but is much less effective when customer orders arrive relatively infrequently. Additional efficiencies associated with zone picking are:
Familiarity. A picker assigned to a specific part of the warehouse will become very familiar with the locations of the items in his or her area, and so will be better able to pick, both more accurately and at a higher rate of speed.
Traffic interference. There are no problems with stock pickers blocking aisles and getting in the way of other pickers, since there is no reason for anyone to stray outside of their assigned area.
Location changes. Pickers will become so familiar with usage patterns in their assigned areas that they may reshuffle bin locations to locate high-frequency items where they can be more easily picked.
Problems with Zone Picking
Despite the significant advantages of zone picking, there are also a few issues to consider, such as:
Central picking area. There must be a method for efficiently reshuffling picked items into their designated customer orders, which may represent a level of organization that does not currently exist within the company.
Responsibility. It can be difficult to track down the reason for a picking error, since a large number of pickers may be involved in each order.
Lumpy demand. The content of customer orders may change over time, resulting in some pickers being intensely busy and others looking for work to do. This issue can be mitigated by periodically rebalancing work loads in the warehouse, based on picking frequencies.