Zone Picking

Zone Picking (Pick and Pass Order Picking): Comprehensive Guide

Zone picking(Pick and pass) is one order picking method used by warehouse managers to optimize operations and reduce labor costs. According to one report, order picking takes up as much as 50% of a warehouse’s operation costs. Consequently, selecting the right order picking method is a matter of saving big bucks in your business’s budget.

What is Zone Picking(Pick and Pass)?

Let’s start with the most basic order picking process: discrete or single order picking. This is where a worker receives an order and walks into the back room or around a warehouse to find the product.

The route they take is rarely optimized. Rather than picking products for multiple orders as they go, they handle one order after another by:

• Walking to the right shelf
• Picking the product
• Walking to the packing and shipping area

They will repeat the process several times throughout the day.

For small businesses, this makes sense. Introducing a complex picking process when you have a small number of SKUs and a limited number of customers can waste time rather than saving it. On the other hand, as the variety of SKUs increases and more customers enter the mix, discrete order picking becomes inefficient.

To more profitably manage demand growth, warehouse managers introduce other order picking methods like batch picking or zone picking(Pick and pass) .

In a batch picking operation, workers pick several units of an SKU for multiple orders, limiting the number of return trips. If seven customers need vacuums, then the vacuums for all seven customers are picked at once.

Others adopt the zone picking(Pick and pass) methodology, which is also known as zone picking. In this approach, managers divide the warehouse into zones and assign workers to each area. Totes or bins move through each zone, collecting SKUs to fill multiple orders at once.

What are the Advantages of Zone Picking(Pick and Pass)?

Warehouses Can Strategically Organize and Pick Different SKUs

Not all SKUs are created equal. Some SKUs may be highly popular while others are ordered infrequently and in bulk. Storing these products sporadically throughout your warehouse can lead to issues like bottlenecks, inaccessible items, and longer pick times.

On the other hand, a strategically organized pick system that stores items based on their characteristics (i.e., high volume, low volume, hazardous, etc.) allows warehouse managers to train staff on specific inventory management requirements and allocate labor efficiently.

With the zone picking(Pick and pass) method, low-volume items can be stored further away from the packing and shipping area while frequently ordered items can be positioned closer to the dock, allowing workers to quickly move popular products.

Creates Specialized Warehouse Workers Who Understand a Category of SKUs

Zone-based order fulfillment allows workers to grow familiar with their SKU category. They can quickly identify products, increasing their overall efficiency and reducing the number of picking errors.

Assigning workers to specialized pick locations also increases employee pride and accountability. It reduces the interchangeability of workers, creating a personal investment in the work and building employee engagement which reduces absenteeism and turnover.

What are the Disadvantages of Pick and Pass(Zone Picking) ?

Difficult to Identify the Source of Errors

Technically, no individual picker has responsibility or visibility over a specific order. They pick SKUs, add them to an order, and pass them on to the next zone. Moreover, there could be several pickers in each zone, depending on the size of the warehouse. As a result, it becomes difficult to assign accountability when orders are shipped out incorrectly.

Product accuracy is no small concern. Inaccurate packages impact profits in a number of ways, including:

• Erodes customer trust: If customers don’t believe that you can get the products they want to their doorstep on time, they won’t bother shopping with you the next time, limiting your repeat customer revenue stream.
• Increases reverse logistics: Reverse logistics is meant to “capture value” by getting unused products back to the company. While it’s an unavoidable part of commerce, it’s not something you want your business to be defined by.
• Impacts your shipping capacity: Every time you use your vehicles or your shipping provider for returns, you’re limiting the amount of space you have for outgoing shipments.

Workers Re-Arrange Pick Zones Based on Preferences

Since each zone hosts dedicated workers, employees tend to rearrange their zones based on personal preferences and managers let them since this improves the pickers’ ability to locate SKUs and quickly fulfill orders. This may also impact the way how stock replenishment is done with the warehouse/zone.

That said, a system based on personal preference can cause confusion when new workers are introduced to the zone. Informal organization systems emerge, making it difficult for new players to quickly learn the ropes and for managers to substitute employees between zones when workers are on vacation, out sick, or leave the company.

Workers May Resent Working in High-Volume Pick Zones

Some zones will require more movement than others. Someone working in a high-volume pick zone will be constantly on their feet moving back and forth. On the other hand, a worker in a low-volume pick zone that experiences bulk orders won’t have much manual work. Moreover, the size of the bulk orders may mean they use machinery like forklifts to pick and move products.

In some cases, this is unavoidable. If someone has a license to operate a forklift or the training to manage hazardous chemicals, they may have a different working situation than their colleagues. But, if it’s simply a matter of high-volume versus low-volume zones that don’t require specific qualifications, it’s easy for resentment to build between different zones, with accusations of favoritism.

One solution is to rotate workers through the different zones on a monthly or quarterly basis. Alternatively, people may specialize in two zones and alternate between zones from shift to shift.

There is a Hard Cutoff Time for Incoming Orders

With the zone picking(Pick and pass) method, orders need to be added to the queue by a certain time. This is because the orders move through the warehouse where they pick up the necessary SKUs in phases. If an order misses the cut-off point, it has to wait until the next day or shift to be processed.

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How to Organize Your Warehouse for a Pick and Pass(Zone picking) System

Choose Between a Sequential or Simultaneous Pick and Pass(Zone picking) System

A warehouse manager interested in a zone picking(Pick and pass) process must choose between sequential (simple) or simultaneous (concurrent) zone picking.

In a sequential zone picking system, an order enters the warehouse management system and moves through multiple zones. Imagine a single order that includes the following items:

• 2 vacuums
• 7 kettles
• 4 irons

Rather than one individual moving through the warehouse, wheeling a bin, and walking around to find the vacuums, the kettles, and the irons, all of these items are stored in specific areas. For simplicity’s sake, let’s say they are stored in the following areas:

• Zone 1 – Vacuums
• Zone 2 – Kettles
• Zone 3 – Irons

The order moves through Zone 1 where the Zone 1 workers pick 2 vacuums, then to Zone 2 where those workers pick 7 kettles, and finally to Zone 3 where someone adds 4 irons.

This order is then sent to the packing area and shipped to the customer. That process is known as sequential zone picking (or sequential pick and pass). Each SKU for the order is picked in sequence.

On the other hand, simultaneous zone picking dispatches all the zones to pick SKUs for orders at the same time.

Let’s return to our package of vacuums, kettles, and irons. Rather than the “order” (in the form of a tote or bin) moving through the different zones, the order is sent to all three zones. Each zone picks the appropriate number of items and sends them on to the staging or packing area where they are sorted by order.

Some warehouse managers find the concurrent process unnecessarily complicated because it adds an extra step at the end. On the contrary, the consolidation stage helps ensure order accuracy by giving workers a final opportunity to double check orders and ensure no SKUs are missing.

The choice between sequential and simultaneous order picking ultimately depends on the nature of your warehouse. If some zones have higher pick times than others, there may be bottlenecks as orders pile up at a slower zone. In this case, it may make more sense to manage the final consolidation of orders later in the process. If the pick times in each zone are more or less the same, a sequential zone picking process makes sense.

Since the zones ultimately remain the same, it is possible to try one zone picking method and then switch gears later if needed.

Purchase a Warehouse Management System or Zone Picking System (ZPS) With the Necessary Features

A warehouse management system can be configured to include zone specifications in addition to the traditional location and facilities designations. A warehouse management system also organizes the overall process by making it easy to move orders through the system and initiate a zone picking workflow. Additionally, a WMS can enhance the security of zone picking.

As a process, zone picking has security built into it by designating which workers should be in which zones. A warehouse management system can keep track of staff by assigning workers specific user IDs so they can only carry out picks in authorized locations.

For warehouse managers looking to implement a simultaneous/concurrent zone picking system, a warehouse management system is essential.

In addition to a warehouse management system, warehouses can also consider implementing a zone picking system (ZPS). While a standard warehouse management system must be customized to fit the requirements of zone picking(Pick and pass) methodology, a ZPS is designed with pick and pass at its core. Guided by the ZPS, totes travel through the warehouse by conveyor, stopping at zones and picking up SKUs as they go.

Determine the Variables Within Your Pick and Pass System

There are several variables that you’ll have to set and occasionally change within your warehouse’s pick and pass system. These variables include:

• Number of zones or segments
• Whether or not you’ll allow totes to recirculate
• Whether or not you’ll allow totes to take shortcuts
• What your specific storage policy will be (random or class-based)

You may decide that it sometimes makes sense for totes to skip zones and circle back around in an effort to spread out the workload. You may decide that you don’t want totes to take shortcuts during a specific workflow. All of these variables depend on the nature of your business and can either optimize (or hinder) your warehouse’s zone picking operation.

Purchase the Necessary Equipment for a Zone Picking(Pick and Pass) Operation

Ideally, machinery powers your warehouse’s zone picking method, but automation is not a matter of simply adding equipment. Instead, automation requires intentional thought about your company’s overall pick strategy, which is different from your company’s pick methodology:

• Vehicle-based picking strategy: A relatively inexpensive strategy that includes equipment like rolling carts and electric pallet jacks. It’s also adaptive: since equipment doesn’t have to follow a predetermined path, the picking methodology can be easily switched.
• Conveyor-based picking strategy: A system that uses conveyor belts and makes it easy to move a large volume of SKUs through the warehouse. However, a conveyor based system is costly to implement.
• Goods-to-person picking strategy: This strategy uses equipment like carousels and robotic picking systems that can significantly improve pick rates, but are extremely expensive and difficult to reconfigure if the business changes.

It’s worth noting that the conveyor-based picking strategy is popular for zone picking based on how easily it moves through the warehouse. Companies that don’t have the resources to implement a conveyor system can opt for a vehicle-based system for their zone picking approach.

Increase Efficiency and Reduce Bottlenecks by Using Zone Picking(Pick and Pass) in Your Warehouse

Labor represents a huge cost center for warehouses and order picking is a significantly labor-intensive process. A zone picking system introduces organization and efficiency to warehouses by increasing throughput, reducing bottlenecks, and boosting efficiency. Zone picking allows warehouse managers to more effectively allocate human resources, increase customer satisfaction by speeding up order fulfillment, and better control inventory using properly configured warehouse management systems and the right automation tools.

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