Order picking is one of the most important functions in the warehouse - whether the customer has a positive or negative experience is based on the results of the picking process. Order accuracy and timely order fulfillment are keys to a successful customer experience. In addition to being a determining factor for customer satisfaction, picking and packing are generally the two areas where companies can gain the most significant labor cost savings.
Efficient picking minimizes walking time and produces high accuracy levels from the pick process. Studies of picking in large centers show pickers may walk 15 miles per day. Having a good inventory control process in place will go a long way toward improving picking accuracy. A clearly labeled warehouse and easily read pick documents, or RF screens, help as well. To reduce walk time, it is necessary to properly velocity slot the warehouse and pick as many orders as possible in one trip through the pick line.
If you’re a conventional warehouse operation, look at the methods illustrated below to see if you are using the most efficient methods. These are typically supported by most Order Management, ERP and Warehouse Management Systems.
For larger distribution centers, voice picking, pick-to-light (and put-to-light), picking modules and robotics automation may give a return on investment for many applications. But, they must be designed to your facility, products and material handling.
7 Ways to Pick Orders
Here are seven ways to pick orders:
- Single line orders – single SKU per order, multiple orders
- One order at a time – one order multi-line
- Cart/Bin – multiple orders sorted as they are picked
- Batch pick and sort –separate sort function
- Zone pick – items are separated by zones and picked in that zone
- Zone pick and combine – separate zone batches are merged at or before packing
- Pick and pass – order is picked to conveyor or cart and pushed to next zone
Let’s take a more detailed look at each:
1. Single line orders
For many e-commerce businesses, more than 50% of their orders are single line orders. They are the fastest and cheapest to pick. Batch all single line orders together for a SKU in order to make one pass through the pick line. This will maximize the pick density and reduce walk time. Single line orders can then be taken to designated pack stations or inducted to the packing area as multiple orders of the same SKU to increase the productivity of the packing function.
When you’re receiving order profiles, if many of the single line orders are back ordered SKUs, cross dock them directly to the pack stations with printed orders, eliminating put away and picking.
2. One order at a time
Handling one order at a time works for companies with few orders comprised of many SKUs on each order. It is inefficient for most e-commerce operations since the travel time required to pick one order at a time is excessive. This is more commonly found in some retail, business-to-business, or wholesale distribution centers, where the orders are large for major customer order shipping LTL or fleet.
This approach is commonly used to pick and sort more than one order at a time, in one pass through the pick line. A batch pick sheet or display is generated showing the SKU, quantity, and location on the pick cart for the picked SKU(s). As the location for the SKU to be selected is reached, the total quantity for that SKU is picked and placed in the appropriate location on the pick cart. When the last SKU has been selected, all of the orders on the cart will be complete and ready for packing.
To implement this method, you’ll need a pick cart that can be used to compartmentalize the individual orders. A pick cart will need to accommodate anywhere from 10 to 12 orders at a time with the capacity to carry larger orders, as necessary. Smaller size SKUs can have many more orders per cart. If cube information is available, the number of orders per cart can be maximized.
One variation of cart/bin picking is to pick directly into the shipping carton. Some pre-work is required to select the correct size carton, but this extra time is offset by the elimination of the need to have a separate packing function. An order can be filled and packed with only one “touch,” thus reducing cost. To accommodate the wide range of picking needs, cart manufacturers offer fixed and flexible cubby hole layout options.
4. Batch pick and sort
One concept that recognizes the desire to reduce walk time is the batch pick and sort option. In this method, orders are grouped together for picking in SKU order. But, unlike cart/bin picking, the orders are not sorted during picking. This speeds up the process and permits more orders to be picked at once. The picked SKUs are taken to pack tables or sorting tables and sorted by customer order.
Time is saved during the picking process, but added time is required to sort the orders into their individual orders. This application is beneficial in larger operations where the sortation process can be automated to various extents to reduce labor. Options ranging from manually scanning barcodes on products to automatic unit sorters are applicable. It is possible to utilize barcode scanning to sort SKUs to individual orders but there will still be a requirement for manual time to be spent to complete the process.
5. Zone pick
Breaking a large warehouse into smaller zones may make picking more efficient. First, designate items to be stored in different warehouse zones. Then, assign each order picker a specific zone in a warehouse. The order pickers will only order pick within their designated zone.
An advantage to zone picking is that if your items are large or dimensional items that cannot be recombined with other items, you can ship them in a vendor carton. Just store the item by zone or even as an item in a ship alone warehouse. Pick tickets are generated as ship alone, single line orders. Labels are then attached and the item is moved to the shipping dock.
6. Zone pick and combine
One variation of the batch pick and sort method is to combine the concept of zone picking where two or more pickers work on the same orders at the same time and then take their selected SKUs to the same sorting area. These independently picked order parts are then combined to complete the order.
7. Pick and pass
Another concept for picking is to employ a pick and pass concept where the picker remains in a relatively small area and the order moves from zone to zone with additional SKU’s picked and added as needed to complete an order. This concept works best with a limited number of SKU’s and orders with a few lines per order.
One major disadvantage is the need to balance the picking requirements and productivity between assigned zones. Usually, a conveyor is used to transport a tote box from zone to zone with another conveyor used to transport completed orders to the packing function.
How to reduce picking time
In addition to the advantages of the methods of picking above, here are some ways to reduce picking time to consider:
Maintain accurate product slotting and location control
Slotting and location control have a major impact on picking efficiency. Nothing slows down picker productivity more than a “warehouse backorder,” or a product that is in the wrong slot or out of stock.
Any picking methods that reduce the travel time or make the picker stationary
These include "pick and pass” and “zone picking” as well as “pick-to-light” and “put-to-light” technologies, described below.
Ease of seeing of the pick list
Depending on the center, there may be several opportunities to improve the pick list. First, is there sufficient lighting to see the pick ticket? Second, is the printing large enough to be able to easily see the item, stock location, quantity, and other details?
Establish hot pick zones
In any picking method, one consideration should be the creation of a “Hot Pick” zone. This zone contains the top selling SKU’s and is located in the most advantageous position to facilitate picking and transfer to packing. Picker’s in large distribution centers may walk as much as 15 miles per day according to industry studies. Hot pick slotting is aimed at reducing walk time and the labor expense to a minimum for best selling items.
Many “Hot Pick” zones are dynamic and change based on the changing sales of each SKU. By having fast selling SKUs together and close to packing, walk time is reduced. This is a good example of using Pareto’s Law, the 80 – 20 rule, where 20% of the SKU’s represents 80% of total unit sales.
READ: Establishing and Running a "Hot Pick" Zone in Your Distribution Center
Picking is a major labor cost in fulfillment. Consider rewarding high performers with incentives. Here are 7 considerations for establishing incentives.
Investing in more advanced technology and automation
As fulfillment centers grow in volume processed, there are a number of advanced picking technologies which should be considered. There is an investment amount in each of these that will need to be cost justified to get a return on investment. Before investigating advanced technology and automation, ensure your company addresses the four foundational pre-requisites that are required to gain the most benefit from your WMS and the automation.
READ: Assessing and Applying the Proper Level of Automation in Your Warehouse
Here are a few technology options that will improve your operation’s picking:
Voice picking to improve accuracy and efficiency
When it comes to applying voice picking, there are many benefits that a warehouse will certainly realize. Typically, companies experience:
- additional picked units per hour and lower costs
- increased work pace with voice picking
- ability to integrate languages other than English and adapt it to employees’ speaking patterns
- improved picking and data entry accuracy
- online data entry and data prep reduction.
Pick-to-light and Put-to-light technologies
Pick-to-light is a light-directed picking technology that can be used in a variety of ways. It is a form of paperless picking where a barcode on a tote is scanned and the LED light directs the picker to put the item in the tote. The picker confirms the pick and a conveyor moves the tote to the next pick-to-light station.
The cost savings come from the picker remaining stationary and eliminating picker travel time. Pick-to-light can be combined with other material handling technology for kit assembly, sorting, carousel towers and case picking. Investment is based on the number of pick stations required. The best applications are high volume of sales for a small number of products.
Put-to-light systems, often called reverse pick-to-light, uses LED light stations to direct pickers to the correct location to sort, or put, items into totes and shipping carton.
Picking modules and automation
Retrofitting an existing center or planning a new one? Investing in pick modules and automation may have an ROI for your operation. Benefits associated with the use of pick modules include increasing picking efficiency through reduced picker travel time; lowering cost to pick product; and using distribution center space more efficiently. Pick modules can be on separate levels, such as mezzanines.
Pick modules must be carefully designed to your center’s requirements and take into account the facility’s layout, type of products handled, material handling, and sortation being used.
Robotics in fulfillment
If you are planning to build or retrofit a large distribution center in the next couple years, integrating robotics is a trend to watch and investigate. We have seen a number of businesses cost justify and reduce picking costs with robotics recently. The early applications are to “assist the pickers” to increase picking rates.
READ: Making the Case for Robots in Fulfillment
Becoming more efficient and accurate in picking customer orders will decrease cost per order, improve the customer service and reduce order fulfillment time.