As consumer product companies go digital with orders coming from a growing list of omni-channel sources, order profiles are evolving rapidly. Oftentimes these profiles are reduced to just a few items per order. To meet these changing demands, digital distribution centers are reviewing their picking methodologies to improve efficiency and to quickly get orders on their way to the customer.
Several order picking processes exist that can be deployed in a digital distribution environment, which can be divided into four major categories: discrete order, cluster, zone, and batch picking. Choosing the correct picking strategy for your center depends on a variety of factors, including order size, warehouse size and business need. By taking into consideration the advantages, disadvantages and best practices for each option, your organization can ensure its picking system meets the demands of your digital order profiles.
1. Discrete Order Picking
In a normal distribution center, discrete order picking is the most commonly used picking process. This type of picking is used for one order at a time, with the picker walking the entire picking area for each order. Discrete order picking has the advantage of being simple to learn as well as being accurate even without using a warehouse management software (WMS) system.
For wholesale companies receiving large-cube orders, this process is highly effective, but, is very inefficient for small cube items, because each order requires an employee to make a trip through the entire forward pick area and return to home-base after each order is picked.
Discrete order picking should be considered for digital distribution only when processing items with large cubic dimensions, when your operation does not have a WMS system and accuracy is a critical business requirement. If your digital distribution center is receiving many small orders or is simply too large for this one-at-a-time picking method, an evolution to a more flexible picking process may be your best option.
2. Cluster Picking
The next step up in efficiency is cluster picking. In cluster picking, multiple orders are picked during a single pass through the forward pick area; the items are picked and then placed by order into containers. The picker will take multiple orders through a single pass of the warehouse, thus multiplying efficiency by minimizing trips through the picking area.
|LP Light Sled, from Lightning Pick, maximizes cluster picking speed in their order fulfillment operations.
Photo: Matthews Automation Solutions
Cluster picking can be achieved more effectively by using a WMS system. The WMS directs pickers through the pick area displaying what to pick and which container to place the item into for the corresponding order. This can also happen in a paper-based warehouse when pick-lists are pre-printed and then manually sorted for like items in the pick area. Paper-based cluster picking is less accurate as pickers may pick or place the wrong item into an order as then try to manage many pick-lists, often a post pick quality control check is used to ensure accuracy – costing efficiency as another process is engaged.
It's most appropriate for digital distribution when handling orders with small cubic dimensions or when your distribution center/pick area is small enough for a picker to efficiently walk through. It also helps to have a WMS system that can direct the picking and putting of many orders at one time in an efficient path.
3. Zone Picking
To minimize walking the whole pick area, zone picking is used when the entire pick area can be broken up into smaller efficient picking zones. Cluster picking is still used with zone picking to maintain the efficiency of picking multiple orders. When orders can be picked into shippable containers, zone picking has the double advantage of reducing the walking while shipping the container as soon as picking is complete. Zone picking typically requires a complex zone routing conveyor system controlled through a WMS system.
Zone picking should be considered for digital distribution when picking items with a variety of sizes, shapes, and storage climate requires the distribution center to be broken into walkable pick zones, and when an appropriate conveyor and WMS are in place.
4. Batch Picking
The next step in improving efficiency is when a small number of items are required on many orders through a batch picking process. Batch picking is used when the entire quantity of an item is picked per wave (or batch) and then consolidated with the rest of items for the order. Batch picking is usually used with other forms of picking (Cluster and Zone) for the slower moving items of the order. Consolidation can happen using an off-line Put-Wall process or a complex sortation systems.
Batch picking is the best option for digital distribution when a small number of items (web-promotional items) are common across a large number of orders. It is also best used when automation can be justified by the reduction of employees to process orders in the distribution center.
The transformation to a digital company means order profiles will continue to change, lowering the number of lines per order as consumers order only what they need at that point in time. As the number of lines per order changes, so will the requirements for picking those orders. Picking professionals will need to transform the distribution center and the picking strategies with the changing requirements to meet the demands of the digital distribution age.
Richard Barnes, a principal consultant for WiPro Ltd., is a supply chain expert and master black belt with extensive leadership experience and a strong background in applying people, process and technology to streamline supply chain operations.