Order Picking Strategies

Various order picking strategies are used to be effective and efficient.

Pick Initiation

Order picking can be initiated in a number of ways. Two common methods are as follows,

• Printed Pick Lists that identify the location and quantity of the items to be picked.
• Pre-printed bar coded labels that are stuck on pick carts, trays, tubs, etc. When passed by a bar code reader, pick locations (and sometimes quantities) are displayed, or printed for picking.

Picking Strategies

Efficient picking can be accomplished by selecting the right picking strategy. Four widely used methods are described below:

• Strict Picking. Strict Picking is a strategy where a picker completes one order at a time. The advantage of this method is that order integrity is maintained throughout the picking cycle – a completed order arrives in shipping, usually picked by a single worker. Additionally, no downstream sorting is needed. Strict picking works best when there are only a few line items to be picked for each order.
• Batch Picking. In Batch Picking, a worker selects items for several orders simultaneously. A major advantage of this method is that the picker completes multiple orders in one tour of the warehouse. If orders are small, pickers may sort to a compartmentalized cart while picking. Otherwise, sortation is required downstream to consolidate orders.
• Zone Picking. In Zone Picking, each worker is assigned to one particular zone. A cart will move through each zone with workers adding products from their particular area as specified in the pick list. With this method, travel distances are significantly reduced. Unnecessary handling can occur when the cart is passed through a zone where no product is required for the order. In this case, a bypass may be used to skip the “no-pick” zones. This method may be appropriate where different equipment is used for picking different types of product, where a single order would be too great a quantity for one picker to pick, or where the dispatch times mean that all the order lines must be picked quickly. It is also used where there are different zones for products, for example where products are separated for reasons of security, hazard or temperature regime.
• Wave Picking. As the name implies, orders are consolidated into waves of work. An advantage of this method is that waves can be created based on rules tailored to meet the needs of the moment. Orders may be released in waves (for example, hourly or each morning and afternoon) in order to control the flow of goods in terms of replenishment, picking, packing, marshaling and dispatch. The timing of the waves is determined by the outgoing vehicle schedule, so that orders are released to allow enough time to meet this schedule. Note that orders may not be released at the same time to each zone. Some examples,
• Pressing orders can be filled first
• The size and content of each wave can be modified
• By a particular carrier, or even a given load
• By a destination

Picking Productivity Concepts

Picking productivity is the key to an efficient operation. Some concepts that can help enhance productivity include,

• Stock Assignment by Activity: Locate popular items where they are easily accessible. For example, an often picked item may be located at the end of an aisle to limit travel distances. Goods that are frequently requested together will be located in adjacent storage bins. Items that are infrequently required will be stored in a remote location. Another technique is to balance picking activity by distributing fast moving items over multiple pick lines. This minimizes situations where some workers are extremely busy while others are underutilized.
• Sequenced Picking: When possible, picking can be sequenced by location. All orders requiring goods from a given area will have those items picked all at one time to reduce travel time. Sequenced picking can also be used to pick goods based on a given carrier which will minimize downstream sorting activity and reduce dock congestion.
• Consolidated Picking: Order fulfillment may cause a given destination to receive multiple packages that are sent in more than one shipment wasting time and shipping charges. By consolidated picking, orders can be sent in fewer packages and/or less shipments. This will minimize time, effort and materials needed in packing, as well as the cost associated with shipping and tracking multiple packages.
• “Golden Zone” Picking: Golden Zone picking is storing popular items in a location that is easily accessible to the picker. The golden zone is at, or near, waist level. It is the most comfortable and least stressful location for repetitive motion working. Goods that are less popular or light weight can be stored where reaching or stretching is involved.
• Computer Control: Computer control systems have been successfully used to help manage inventory as it relates to picking. The most widely known computerized picking system is called the Pick-to-Light system.