Inventory Management, Order Management / ERP Systems

Order Picking Methodologies

Order picking is one of the most important processes in warehouse operations. It can contribute almost 40% to 50% of the operation cost incurred by the warehouse in comparison to receiving, storage, and shipping processes. It has a direct relation to customer satisfaction. The more efficient your order-picking process, the more orders you can process at any given time.

What is Order Picking?

Order picking is the process of retrieving an SKU from a storage location and transporting the SKU to the packing or dispatch area. Orders are picked up based on manual picking instructions or instructions generated by a WMS.
A WMS can generate the pick list based on different methodologies.

These methodologies are chosen based on the size of the warehouse, the number of different types of SKUs handled by the warehouse, and order volumes.

There are multiple methodologies that can be used to pick orders. They most commonly used ones are:

Consignment/Order Based Picking
Zone Picking
Batch Picking
Wave Picking

Let us look at each of these picking methodologies in more detail:

1. Consignment or Order based Picking

In consignment or order based picking methodology, a picking instruction is generated in response to an order placed by a customer. The instruction will specify all the SKU’s to be picked for that particular order, and the picking operator, picks the parts as per the generated instruction. The issue with this kind of picking is that, there are a very high percentage of unwanted or repeated movements across the warehouse. Also, as only one order is picked by one operator, picking lead time is very high which results in a lower picking efficiency. This methodology is suitable for Picking to be carried out for large orders (meaning with many lines) for a fewer customers. For example, picking for your distributor network. Since parts are picked for specific orders / consignment, there is no sorting overhead at the dispatch bay.

2. Zone Picking

In zone picking, the entire warehouse is divided into specific zones and one picking operator is assigned to each zone. Orders are consolidated, and picking instruction is generated zone wise and assigned to picking operator of that zone. As soon as the picking operation is concluded in one zone, the orders are passed on to the next zone. Automation may be achieved with effective use of conveyors between zones.

3. Batch Picking

In batch picking, orders are consolidated to ensure that a picking operator does not visit the same location multiple times. Multiple orders are consolidated and picking instruction is generated. The picking operator moves from location to location while picking up SKUs from several orders. This type of methodology is suitable for high traffic movements in and out of same warehouse locations. Since parts are picked for multiple orders, this methodology will require sorting before the products are ready for dispatch.

4.Wave Picking

Wave picking is a variation of zone and batch picking. In wave picking, SKU’s are picked in waves, that is, multiple pick operators simultaneously pick parts from several orders. Similar to zone picking, the warehouse is physically divided into zones, but unlike zone picking, orders are not passed on to the next zone, but picked at the same time. Wave picking is one of the quickest picking methodologies and has a very short cycle time, but at the same time sorting and packing can become tricky as SKU’s from multiple orders arrive at the same time. To simplify sorting operations, conveyors can be used to transfer the picked SKU’s from the picking area to the packing / dispatch area. Automated sortation devices may be used to sort the picks by orders. The number of sorting slots available will determine the wave size, i.e. the number of orders that can be included in a particular wave. This methodology is typically where we have very large number of order with few line items such as e-Commerce orders.

Conclusion

The type of picking methodology to be adopted by a warehouse depends on the following criteria:

Size of the warehouse
Number of distinct SKU’s handled by the warehouse
Order frequency
Average order quantity & lines per order and
Average picks per order

The above factors should be considered to identify the right picking methodology. Choosing the right picking methodology can help your business reduce errors and also ensure that targeted timelines are adhered to.