What is zone picking? Improve Pick & Pack Time and Accuracy
What is warehouse order picking?
Warehouse order picking is the part of the pick pack and ship process involving pulling (picking) a product out of storage or warehouses to fulfill a customer’s orders. Successful warehouse picking is a critical step in order fulfillment, and this process requires high technology equipment and labor-focused processes. There are several distinct types of warehouse picking processes. In this article, we examine the type called zone picking.
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Why is warehouse picking process important?
Because there are so many different types of products and warehouse layouts, the efficiency of a particular picking method can vary greatly. Therefore, you should take care to select the picking strategy that works best with your needs. By doing so, you may reduce labor costs, picking errors, minimize walking, minimize operating costs, improve customer satisfaction, and even improve morale.
The warehouse picking process is generally segments into 4 types. These are piece picking, batch picking, zone picking, and wave picking. For more information on the various types of picking process, see our article on the types of picking.
What is zone picking?
Zone picking is a type order picking process that splits team members into assigned zones in a warehouse for their specific picking activities. Instead of each team member picking items from anywhere in the warehouse, the zone picking strategy limits their movement only to whatever assigned zone they are responsible for.
In other words, zones have discrete picking teams responsible for only those areas. The zone specifications such as size or quantity may vary depending on the warehouse and their specific needs. However, zone picking assumes there are multiple zones (more than one zone), and warehouse managers divide all the zones to specific employees or teams.
What are the advantages of zone picking?
A good summary of zone picking advantages is: improved warehouse efficiency for larger scale operations. Although this is helpful for businesses of every size, big warehouses with a wide assortment of product types often reap the greatest benefit with zone picking compared to other picking strategies.
Zone picking works well for warehouse operations with customer requirements that tend to rapidly shift from time to time. These operations may include warehouse processes, order fulfillment process, cutoff point, scheduling window or scheduling period, and even the number of or location of a packing area. The reason zone picking works well for this kind of flexibility is because it enables multiple kinda of process across each different zone. This may even be true for product groups, where a zone picking system can group a process by product and employ that throughout the entire warehouse.
Improved Employee SKU Knowledge
When the scope of an employee’s work is in a single area rather than different zones, that employee can expect to gain greater awareness of their area of responsibility. This is because there is less knowledge to juggle, and the time spent is a smaller area of expertise. It’s like the old saying, “Jack of all trades, master of none”. This improved awareness comes in handy any time there may be an issue or question about that particular zone.
Improved Picking Speed
Zone picking has the tendency to reduce the total walking distance for picking activities. This is because employees remain in a smaller geographic area in the warehouse. Multiple orders pick simultaneously without requiring additional travel to the next zone. Additionally, the improved awareness of employees for their particular zone results in a much faster picking process for any given SKU or item.
Improved Order Picker Accuracy
Improvements seen by zone picking process may not only include the speed at which employees can pick, but also the order picker accuracy. Instead of a complex combination of multiple orders from various zones in different areas of the warehouse, zone picking requires a smaller set of requirements within a specific zone. In discrete order picking, however, greater potential for errors introduce unless all the SKUs have similar service requirements.
Disadvantages of Zone Picking
No system is perfect and zone picking can have disadvantages. These disadvantages may discourage you from a zone picking strategy in favor of other picking methods or even a combination of methods such as “zone wave picking” or “zone batch picking”.
Multiple Contact Points
The items pass multiple contact points. Pickup items move between zones and eventually land in sort and packing stations before moving to shipping. With more touch points, there are more opportunities for human error. The pick-up of the items into a container can reduce touch and improve accuracy.
Reduced Error Tracking
Due to the increased variability of total number of touches in the zone picking system, tracing errors back to responsible employees is increasingly difficult. For this reason, you may prefer to combine zone picking with another picking strategy. Otherwise, warehouse managers may spend an inordinate amount of time tracing errors. If you are confident in your order accuracy, however, this error tracing problem is much less significant.
It’s important to note that picking errors easily become a significant problem when dealing with large warehouse picking operations. This is especially true with combined with other methods, which we discuss later in this article. In a smaller piece picking system, a single issue may not balloon to become a large problem, and is easy to trace and correct.
The zone strategy, however, often involves extra variables to trace such as multiple scheduling windows, process variations from one zone or one shift to the next shift, and even changing order picking strategies based on outbound process. A single scheduling period or scheduling window may differ in process from one zone to the next. To combat this, ensure that your warehouse order picking system grants specific user ids for warehouse picking associates. In this way, tracing picking errors requires much less detective work.
Difficulty Balancing Zone Workloads
Depending on the number of zones and scale of the warehouse picking and shipping operations, distributing workload becomes increasingly difficult. This workload imbalance occurs when picking activities funnel into a small number of zones. A warehouse manager should keep a close eye on the workload of each zone and adjust as necessary. If the zone picking system remains unbalanced, employees in busier zones may suffer from increased fatigue. As a result, employee morale and order accuracy suffers.
How does a zone picking system work?
Pickers usually work within their zone and only pick SKUs for orders within their zone. However, zone picking occurs in two main types: sequential zone picking and simultaneous zone picking. These two zone picking processes operate slightly differently.
Simultaneous Zone Picking
In simultaneous the zone picking method, multiple workers pick items from their zone for a single order at the same time. These picked items do not combine for the order until they arrive at the packing area. In this way, orders process faster but require an additional step as compared to the sequential zone picking method.
Sequential Zone Picking
The sequential zone picking process integrates the order into a single bin. Instead of multiple zones picking items at the same time, each zone picks into a unified bin before passing onto the next zone. In this way, all the items arrive together in a single bin at the packing area.
Zone Picking Variables
Because there are different warehouse types, not every zone picking strategy is the same. Warehouse layout, equipment, personnel and product mix affects all aspects of the warehouse operation and hence picking strategy. Assuming you have decided zone picking is the optimal strategy for your business, next you need to decide how many zones to segment, and how to segment them. For example, zones may segment by product type, volume sales, or location in the warehouse. Just remember, the goal should be to increase efficiency but also balance the workload of zones.
The main variables to take into consideration in deciding the best zones segmenting strategy are:
- Warehouse Size & Layout
- Number of Zones
- Number of SKUs
- Type of Storage (i.e., pallet or bin)
- Customer Requirements by SKU
Zone Picking Best Practices
Zone picking best practices don’t differ much from traditional piece picking (or discrete order picking) however there are some notable considerations. Primarily, warehouse managers maintaining these picking methods should emphasize efficiency above all else. This is because efficiency leads to greater capacity and even fewer quality issues. Capacity and quality are generally the most difficult metrics for a large-scale warehouse. To do this, a reduction in touches, time per order, and walking distance must consist as top priorities.
Most of these happen with simple steps such as placing high-turn inventory locations close to the “home run” area, whether that be a packing station or work order station. Other best practices include maintaining a clean and safe working environment that is clutter free.
Implementing a Zone Picking System
Large scale warehouses today operate on digital inventory systems called warehouse management systems (WMS). Usually cloud-based, these are unified systems that control the warehouse picking operations. If you are considering zone picking, you should have a warehouse management system. Features of these systems include labor flow, production flow, zone organization, and many other kinds of oversight.
A warehouse order picking system works best with digital scanning of materials as they receive and move through each step. Without this, the potential for mistakes increases. This may require individual barcode scanners at specific checkpoints so the WMS can automatically move material from segment to segment.
Additionally, warehouse managers must decide which storage system is best for the customer’s needs and the warehouse’s picking strategy. For example, pallet storage and pallet picking may work for orders of large quantities of material (i.e., bulk orders) to single addresses. However, pallet picking becomes cumbersome and inefficient for single unit small parcel shipments.
Combining Zone Picking with Other Picking Methods
Although zone picking is typically a standalone method, flexibility is an important differentiation factor against other order fulfillment methods. Businesses may combine these techniques with other methods such as wave picking. For example, zone wave pick (also known as wave picking) enables workers in scheduled blocks (waves) to pick orders in respective zones at once. Each wave usually groups based on a shipping schedule or other factors to reduce bottle necks in efficiency.
Another type of combination is “zone batch picking”. This is a combination of batch picking (also known as cluster picking) and zone picking. In this type, an employee may pick multiple orders within their zone simultaneously rather than a single order at a time. Picks of this type group (batch) based on common factors such as SKU, carrier, or even assembly line process. The goal of this combination is to minimize walking per order for warehouse picking teams.
Whether you specifically utilize the zone wave picking strategy or some other combination of picking strategy, make sure the strategy you use is right for you. If your warehouse management system, warehouse size, or fulfillment processes don’t match well with a particular strategy, move onto the next one.
What are the four types of order picking?
It’s easy to get overwhelmed when considering the order picking process. While there are lots of ways to combine the various warehouse picking methods, it helps to consider the 4 main types of picking methods. These 4 types are piece picking, batch picking, zone picking, and wave picking. For more information about these 4 types of warehouse picking systems, you can see our article covering that topic: 4 Picking Methods and Which is Right for You.