Warehouse Order Picking: 8 Strategies & Methods to Consider
In order fulfillment, few processes are as time- and labor-intensive as your picking processes. Luckily, there are a number of steps that you can take to optimize your picking process, by intelligently leveraging labor and other material handling technologies. But before you invest in technology or automation to support your picking processes and reduce operating costs, it is first important to ensure you are leveraging the right picking strategy for your business.
Unfortunately, there is no one picking strategy that will work best for all operations. Your order profile, material flow, physical layout of the facility, number of line items in an order, labor availability, and how/when orders are released by your management system are all factors that you will need to consider when thinking about selecting a picking strategy. What works best for one operation may not work best for another.
This leaves you with the difficult task of determining which picking strategy will be best for you. And with so many different potential solutions to consider—batch picking, cross picking, zone picking, parallel picking, pick and pass, wave picking, waveless picking, overlapping waves—it can be difficult to even know where to begin.
Not sure which strategy makes the most sense for your operation? Speak with a member of the Conveyco team!
Why is picking orders correctly so important?
Picking is an integral part of the order fulfillment process and is largely responsible for overall warehouse efficiency. It is crucial that warehouse managers are keenly aware of their picking options and determined to integrate systems that provide inventory accuracy throughout all warehouse picking processes.
To ensure customer satisfaction, warehouses and distribution centers must guarantee individual items (SKUs) are being picked in an accurate and timely manner. This highlights the need for a fulfillment process that keeps the entire supply chain in order, while also keeping up with customers’ demands.
Picking orders correctly and efficiently is the key to having a successful business. Without set picking strategies and methods (processes), order picking can turn into a stressful and confusing process, which can, in turn, reflect negatively on the operation as a whole.
Ways To Improve Order Picking Accuracy
Inaccurate orders cause your operation to waste valuable time, resources, and capital in the correction process. As mentioned, a confusing order picking process reflects poorly on you. Your customers can lose trust in your system and will likely take their business elsewhere. It is crucial for customers to trust that when they order something, they’ll get exactly what they asked for.
The key to avoid losing current and potential customers is improving your order picking accuracy. Evaluating your operation’s warehouse picking process, embracing a smarter slotting strategy, and visually scanning orders are just some of the ways to take your operations to the next level.
With this in mind, here are a number of strategies you can use to remove some of the confusion and guide your business toward the right option for your operations.
Software Driven Order Picking Methods
1. Wave Picking
Wave picking works by grouping orders into a batch, which is released for picking in a single wave. The name comes from the motion of pickers working from one end of a facility to the other end, much as a wave travels across a surface.
A batch in wave picking is static; i.e., it will not change once a wave has begun. Once a worker picks one item, they move immediately onto the next pick, and the next, etc., until the wave is complete. The items that they have picked are then sorted, consolidated, packed, and shipped as necessary.
Benefits of Wave Picking
One of the main benefits of wave picking, and the reason that it is so common in order fulfillment, is the fact that it gives pickers a large workload that can be completed in a single walkthrough of a facility or pick module. This has the potential to significantly reduce travel time. B2B operations or others that receive high-volume orders multiple times per day can benefit from wave picking.
2. Waveless Picking
In wave picking, batches are static; once they are released, they do not change. In waveless picking, however, batches are dynamic. This means that as older orders are completed, new orders are added into the batch constantly. In this way, there is no “wave” because the wave technically never ends.
Because new orders are constantly added to the batch, each time a picker completes a pick, the system must check to see if the next pick is still the best next one from their current location. If it isn’t, then they will be routed to a new pick instead.
Benefits of Waveless Picking
Waveless picking is often leveraged by ecommerce operations that must meet a high demand for same- and next-day shipping from consumers. This is due to the fact that the batches in waveless picking are constantly refreshed to add new orders, with priority given to those with the most aggressive shipping demands. This dynamic refresh is one of the greatest benefits of waveless picking.
3. Overlapping Waves Order Picking
Overlapping waves work much the same as regular wave picking, in that pickers work in batches to pick inventory. The key difference, however, is the fact that in wave picking the first wave must be complete before the next wave can begin. With overlapping waves, this is not the case. Instead, once the first wave reaches its peak and begins to become less productive, the next wave is released. This means that by the time the first wave is done, the next wave will already be approaching its peak, and the next wave will be released shortly after that.
Benefits of Overlapping Waves
The main benefit of leveraging overlapping waves is that it is extremely effective in “leveling out” the peaks and valleys of productivity that are commonly found in facilities that use wave and waveless picking. This allows for a more consistent and predictable throughput, as well as for greater labor and equipment utilization.
Order Picking Strategies
The order picking methods discussed above are warehouse software (WES, WMS) based and can be combined with different picking strategies in each zone depending on the technologies, order profiles and business requirements. Below is a look at 5 picking strategies you should know.
1. Discrete Picking
In discrete picking (also known as single order picking) a picker picks a single order SKU by SKU from start to finish before moving on to the next order. This is by far amongst the simplest of all picking strategies. Because it is labor intensive, time consuming and inefficient, it is not well-suited for most operations. Many organizations start using this methodology and then improve by incorporating intelligent pick lists and then RF picking.
Benefits of Discrete Picking
While discrete picking or single order picking isn’t well-suited for larger, more complex operations, it can be adequate for smaller operations that only process a handful of orders at any given time. The primary benefit of discrete picking is that there is little to no investment in automation technology compared to many other options.
2. Batch Order Picking
In batch picking, pickers process multiple orders at the same time. Typically, orders are batched depending on the similarity of the SKUs in each order. This allows the picker to pick the same SKU for multiple orders at the same time, reducing their overall travel time within the warehouse and increasing the efficiency of the overall pick. This method is often employed when working with Goods-to-Person technologies such as AS/RS, and AMRs with integrated pick-to-light systems.
Benefits of Batch Order Picking
The primary benefit of batch order picking is the fact that it reduces travel time by batching together similar orders and SKUs, which works to improve the operation’s speed-related KPIs. Batch picking works best for those operations that often process orders with Pareto 80/20 type similarities.
3. Zone Picking
In zone picking, the warehouse is essentially divided into different sections, areas or “zones.” Each picker is assigned a specific zone, where they travel and remain to pick SKUs as required for the orders currently being processed.
In some cases, an order might be compiled completely out of SKUs from a single zone, but in other cases it will require SKUs to be picked from multiple zones. In these cases, as a picker completes the pick from their zone, they will pass the container or tote containing their portion of the pick off to the next zone. This can be done manually, or through the use of carts, autonomous mobile robots (AMRs) or conveyors that deliver the tote to the next zone. In cases like this, zone picking is sometimes also called pick-and-pass.
Another option is to have a centralized order consolidation zone or pack-out. This is where totes each containing a portion of an order are routed to and consolidated into one tote or shipper to be packed.
Benefits of Zone Picking
Because pickers do not travel throughout the entire warehouse, zone picking is often more efficient compared to other picking strategies. It allows the best technologies per zone to be deployed for its SKU population. It can be particularly beneficial for reducing labor and for operations that experience congestion in multiple areas, as it limits traffic to one (or a handful) of pickers per zone.
4. Cluster Picking
In cluster picking, the picker will simultaneously pick multiple orders. Unlike batch picking, where the picker picks the same SKUs for different orders, cluster picking typically involves orders that are not similar. In order for cluster picking to work efficiently, the picker will typically work with an order picking cart or AMR that has compartments to hold multiple orders, and which will automatically direct the picker to the location of the next SKU.
Benefits of Cluster picking
Cluster picking will reduce travel time when picking orders, helping to boost the efficiency of the operation. That being said, it’s not as efficient as batch picking. Therefore, cluster picking is often better for operations that must process a large volume of orders at once, but which do not often process similar orders.
5. Robotic Picking
With robotic picking, individual SKUs (whether pieces or inner packs) are picked out of storage by a robotic device, such as a robotic arm. The arm will often immediately pack the items as they are picked, into a shipper allowing for a fully-automated picking process.
Benefits of Robotic Picking
Because robotic picking removes the manual labor associated with the actual picking process, it is an excellent option for operations looking to minimize or eliminate their labor costs.
Technologies to Support Your Picking Strategy
Regardless of what picking strategy you ultimately decide to leverage within your operation, there are many different technologies that can help you improve your efficiency and performance. This includes:
- Pick-to-Light (PTL)
- Pick-to-Voice (PTV)
- Augmented Vision
- Radio Frequency (RFID)
- A-Frame Dispensing
- Autonomous Mobile Robots (AMRs)
- Automatic Sortation
- Automated Storage & Retrieval Systems (AS/RS)
- And more
How To Improve Your Order Picking Strategy
Ultimately, the right picking strategy for your operation will depend on factors that are unique to your business.
What do your orders look like? What are your shipping and labor requirements? What is your required level of throughput? What technologies are you leveraging to support your operation? What strategies are supported by your WMS? Do you have WCS or WES? How effective are the WMS, WCS or WES in improving your labor and equipment efficiencies?