3 Warehouse Order Picking Strategies to Maximize Throughput and Accuracy

When it comes to warehouse picking strategies, unfortunately, there isn’t a one size fits all approach. Most often one picking strategy in combination with one or more of the additional picking methods is utilized to reach the goals of the operation. To determine which of these order picking strategies is right for you, many factors need to be considered.

Factors to include when determining warehouse picking strategies:

    • Order profile
    • Percentage of single line item orders
    • Material flow in the facility
    • How and when orders are released to the system
    • Ability to flex labor during slow and busy times
    • Physical layout of the facility including order picking, consolidation, packing and shipping areas

As a result of the ecommerce boom, and amplified by COVID-19, there has been a shift from picking full cases and pallets to picking “eaches”… as fast and accurate as possible. Here, we’ll review the options relative to piece picking or picking “eaches” for order fulfillment. These order picking strategies do translate to case picking or pallet picking, but with modifications for larger sized handling.

 

3 Order Picking Strategies to Consider

OrderPickingSrategies

1. Pick and Pass

Using a pick and pass strategy, items for an order are picked in each zone in the warehouse until the order is picked complete and is ready to be sent to packing and shipping. Each zone can incorporate different storage technology, but requires inventory management software to manage the order fulfillment process. As orders come in, the items from zone one are picked, then travel in a tote or shipping container via a conveyor or by manual delivery to zone two. The order continues traveling from zone to zone collecting the required parts from each zone until the order is complete. Picking directly into the shipping container instead of a tote eliminates the need for the order to be repackaged for shipping.

With intelligent routing, orders can bypass zones where no parts are required. In a warehouse with five zones, filling an order where all items required are in zone two can take longer if the order must originate in zone one and travel through all five zones before reaching shipping. Intelligent routing allows you to fill orders faster by bypassing these unnecessary zones.

The key benefit to a pick and pass strategy is it eliminates the need for order consolidation.  When they arrive in the packing area, they are complete and ready to be shipped.

 

2. Parallel Picking

In a parallel picking strategy, each worker is still assigned a zone; but all zones are picking the same orders in parallel. Instead of the worker passing the partial order to the next zone, the partial order is sent to a consolidation area where it awaits the arrival of the rest of the parts needed for that order. Once all parts required from each zone arrive at consolidation, the parts are matched up to create a complete order. A consolidation zone is required in a parallel picking strategy to match up all of the orders from each zone for shipment. (LINK TO ORDER CONSOLIDATION BLOG)

The key benefits of parallel picking are pickers can work independently in each zone, parts can be handled differently in each zone depending on size and product velocity and orders combined in consolidation can be checked and verified increasing order accuracy.

 

3. Wave Picking

Instead of picking discrete orders, in a wave picking environment operators are picking order lines. Lines are then combined from the various warehouse zones into discrete orders in the consolidation area.  In this scenario, operators are often picking directly to conveyor which transports the items to the consolidation area.  Consolidation can be done manually, or can be automated using technologies such as horizontal carousels or high-speed sorters.

The main benefit here is the picking process is fast! Instead of picking batches of orders, your team is picking waves of line items. The picker doesn’t care what order the SKU goes into, they know they need to pick a quantity of 50 to fulfill the wave of 100 orders they are working on. Once they pick those 50 items, they don’t have to visit the pick location again to fulfill the wave of orders.

It is common to see a wave picking strategy in operations picking a lot of single line orders, for example in ecommerce. This takes the sortation out of the process entirely. Therefore, once the item arrives to packing and shipping, it gets placed into a shipping container and sent out the door.

You can also flex labor with this strategy, pushing more labor into the zone as needed. Since the workers are only concerned with picking lines, flexing labor to meet faster demand is easy in wave picking.

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Batch Picking and Cross Picking to Enhance Performance Further

To further improve your overall picking performance, consider the following picking methods as enhancements to the picking strategy you’ve chosen.

  1. Batch Picking: This is where orders are grouped together into batches to increase picking productivity. Batch picking requires a storage method, a batch station and inventory management software that manages the batch picking process. For more information on batch picking, check out this blog post specifically about this strategy.
  2. Cross Picking: Cross picking combines two batch picking work zones for increased productivity. The concept is simple: Two automated pick zones — comprised of horizontal or vertical carousels or VLMs — are positioned face-to-face. In the middle of the two pick zones is a batch station consisting of a side-by-side roller conveyor with a series of alternately angled flow racks (also called slides) on top. Atop the conveyor and beneath the slides sit two rows of order totes, back-to-back — one for each pick zone. The entire system is light-directed. For more information on cross picking, there’s another blog post for you.

 

Technologies to Improve Order Picking Accuracy 

Now remember those business objectives I mentioned? There are additional tools to further improve your inventory accuracy within these strategies. Pick to light technology comes in handy when you want to increase accuracy. From transaction information centers using LED lights to display part name, number and quantity to pick, to light pointers directly pinpointing the item to pick within an AS/RS, pick to light technology can increase accuracy by up to 99.9%.

pick-to-light-storage-system

Also, using a bar code scanner to confirm a pick before placing it into an order tote can ensure the worker has picked the correct item before it ever leaves the facility.

In closing...

Review your facility layout. It is important to organize your facility into zones to support these picking strategies. Zones are most commonly created  based on SKU type or SKU velocity to create pallet, case and forward pick zones. Zones may be determined by physical storage or handling characteristics, fast/medium/slow moving lines, security or hazardous considerations and different temperature or climate controlled requirements.  Often each zone has a different type of storage technology to most efficiently handle the SKUs in that zone – from flow rack, vertical lift modules (VLMs), vertical carousels, horizontal carousels, mini loads, multi-shuttle systems to standard rack and shelving. This is the foundation for your picking strategy performance. Keep in mind, you will see the biggest performance gains when you enhance your picking strategy with one of the additional methods or technologies we’ve outlined.