When optimizing the picking process in a warehouse, it is important to recognize two key concepts. First, no one strategy or technology fits every case. Second, effectively improving warehouse operations requires a combination of data collection, process improvement, and technology.
As a best practice, warehouse managers should conduct an ABC analysis, properly document and review the current process to detect inefficiencies, and improve warehouse processes before introducing any form of warehouse automation and/or warehouse technology. For effective optimization of the picking process, a warehouse manager must match the correct picking and automation strategy with the goods being handled (e.g. full pallets, full cases, individual units, cargos).
So, let’s dig into the steps needed to optimize this critical warehouse process.
1. Conduct ABC Analysis/Order Profiling
The first recommended step is to collect data to understand how efficiently or inefficiently we are managing inventory. One of the best ways to do this is by conducting an ABC analysis and/or order profiling.
An ABC Analysis allows a warehouse manager to classify cargo into three categories (ABC) based on order volume. The idea here is to organize inventory such that the highest volume inventory (A) is stored toward the front of the warehouse, while the lowest volume inventory (C) is moved to the back. The result: less walking time and fewer man-hours required to complete picking operations.
The following image shows a warehouse where high volume inventory (RED) was spread across the warehouse, resulting in unnecessary walking time. After the analysis was conducted, high-volume items (RED) were moved to the front and low-volume items (GREEN) to the back.
For warehouses and distribution centers that do not process customer orders, an ABC analysis can be done based on receiving and shipping volumes.
2. Select the Correct Picking Methodology
When it comes to picking, a warehouse manager also needs to consider which picking methodology to adopt. While most operations still rely on the Pick-to-Order approach (one of the most inefficient approaches to picking), there are methodologies that can be implemented to significantly improve and increase warehouse efficiency.
The goal here is to apply one picking methodology or a combination of methodologies so as to reduce travel time between pick locations.
Depending on the operation, movement between pick locations can account for up to 50% of a picker’s time.
In the Picker-to-Goods method, the picker is assigned to an order (or part of an order) and he/she travels to the location where the goods are stored. Then, the picker collects the item and delivers it to the dispatcher to prepare the goods for shipping.
The following are the most common Picker-to-Goods methods used in today’s warehouses and DCs.
In the Picker-to-Order method, the picker is responsible for collecting all items related to an order. With a detailed list of the items to be collected, the picker travels to the locations where the goods are stored and proceeds to pick the entire order.
This approach is only effective with orders that have a low number of SKUs/items. Because orders are processed one at a time, order accuracy rate increases and cargo handling is reduced as goods are moved from storage to shipping all in one step.
The downside to this approach is that it is very inefficient and inaccurate for orders with more than one item/SKU. As the number of SKUs/items-per-order increases, the number of errors increases.
Cluster Picking is more efficient than Pick-to-Order because it allows pickers to collect multiple orders at the same time.
In this method, the system provides a picking list to the picker with the most efficient route to pick multiple items at the same time. As the clerk collects individual-item orders, items are separated into individual bin partitions to reduce/eliminate order errors.
In most cases, warehouse management systems (WMS) capable of supporting Cluster Picking can also prioritize item picking if there is a need to give priority to one set of orders over another.
In Zone Picking, SKUs/items are divided across multiple zones within the warehouse, and dedicated pickers are assigned to specific zones.
As orders are received, they are moved from one zone to another via trolleys, cages, pallets and/or conveyors. If an order has more than one SKU, multiple picking lists are generated and assigned to each zone for specialized pickers to fulfill them.
The specialization of pickers in zones and the SKU-location knowledge they acquire, combined with the ability to fulfill multiple orders simultaneously, significantly increases the speed and effectiveness of the picking process.
Zone picking is best used in warehouses and distribution centers processing large numbers of SKUs and multiple orders.
In Wave Picking, orders are grouped and released to pickers at specific points in time during the day and across different zones, depending on how long it takes to pick the orders. This is done to align the picking process with specific events such as shipping schedules, replenishment cycles, shift changes, available workforce, etc.
Wave Picking is more effective when the process is managed through a warehouse management system that supports Wave Picking. In this case, the WMS releases sequential waves of orders throughout the day depending on specific criteria.
One of the advantages of Wave Picking is that it helps to reduce the workload variation of each picker by allowing the picker to focus on executing a specific task (case picking, packing, repack picking, etc.) on each Wave Pick.
46% of best-in-class companies are more likely than others to use advanced pick methodologies.
3. Introducing Technology
We have covered two fundamental approaches to optimizing the picking process. Now it’s time to introduce the technology aspect.
Barcode scanners are one of the simplest but most effective ways to improve warehouse operations. By using barcode scanners, we can effectively identify products, locations, containers, and more.
Using a combination of barcode scanners and picking lists, warehouse clerks can confirm they are picking the right product for the right customers from the right locations. This warehouse technology allows for faster and near error-free collection of data and product validation.
On average, the technology error rate when using barcode scanners is 1 in 3 million.
Wearable Computers are another warehouse technology that can have a significant impact in improving warehouse processes.
Wearable computers provide a small screen and keyboard that allow pickers to interact with the WMS from anywhere in the warehouse in real time. In some cases, these devices provide the capability of a finger-mounted device to provide barcode scanning capabilities. See below:
The wearable aspect of this technology leaves pickers with both hands free to handle cargo. This in turn significantly reduces the likelihood of accidents and product damage.
Before adopting any wearable solution, decision-makers must confirm with their WMS vendor that their software is compatible with the desired wearable computer.
Voice Picking brings a high level of both efficiency and effectiveness. With voice picking, operators are equipped with a headset and microphone that are directly connected to the WMS over local wireless warehouse networks.
During the picking process, the operator also interacts with the WMS via voice commands, and the system provides verbal instructions to the operator as to the place, product, and quantities that he/she needs to pick.
Some of the most important benefits include but are not limited to:
• Increased accuracy & productivity
• Multi-language capabilities
• Reduction of data entry errors
• Improved safety through hand- and eye-free technology operation
• Increase availability of picker time
There are more advanced (and expensive) technologies such as Pick by Light, RFID, and Wearable Glasses that can considerably increase efficiency. However, the technologies described above offer solutions that are both affordable and accessible while yielding great results.
As a final note, it is important to emphasize that the key to optimizing any warehouse process lies in the ability to collect and analyze data, review/improve existing processes, and introduce the right technology in the right places. It is easy to undermine one or the other by failing to complete a comprehensive approach or implementing one that neglects any of these three steps, which could result in a diminished return of investment and/or a loss of capital and time.
To learn more about the different warehouse processes and how to optimize them, click here.