Order picking has long been identified as the most labour-intensive and costly activity for almost every warehouse. The cost of order picking is estimated to be more than half of the total warehouse operating expense.
Any underperformance in order picking can lead to unsatisfactory service and high operational cost for its warehouse, and consequently for the whole supply chain. In order to operate efficiently, the order picking process needs to be robustly designed and optimally controlled.
The Order Picking Process
Order picking is the process of pulling items from inventory in the warehouse to fill a customer order. In most cases, the process is quite straightforward. The warehouse operators and supervisors should need minimal training.
In situations where order picking is entirely automated through the use of warehouse robots, employees may not set foot on the warehouse floor, unless there is a problem.
Methods of Order Picking
1. Piece-Picking or Picker-to-Part Method
The order picker moves to collect the products necessary for one order. This is a simple method of order picking which requires sending an employee around the warehouse with an order list and a box or container. The picker pulls each item, following the most efficient route. This is not the most efficient method.
2. Zone-Picking Method
Each order picker is assigned to one specific zone and will only realize order picking within this zone. This order picking has each worker in charge of a section and pulls from her section to fill incoming orders. The box may move through several sections until the order is complete, often along a conveyor belt.
3. Wave-Picking Method
Wave picking is very similar to discrete picking in that one picker picks one order, one SKU at a time. The main difference is the scheduling window. In discrete picking, there is not a scheduling window whereas in wave picking there is. Orders may be scheduled to be picked at specific times of the day, which is usually done to coordinate and maximize the picking and shipping operations.
4. Sorting-Systems Method
There is no movement of the order picker, the products are brought to him by an automatic system (i.e. a conveyor system, automatic storage …).
5. Pick-to-Box Method
No movement of the order picker, the picking area is organized so that there are a number of picking stations connected by a conveyor. The order picker fills the box with the products from his station and the box moves to the other picking stations until the customer order is complete.
The Order Picking Techniques
It is important that a warehouse continually improves the efficiency in the order picking process. This is crucial to retain satisfied customers, improve accuracy and ensure growth of the organisation. There are several techniques to improve the warehouse order picking process.
1. Touch items once
Focus on preventing errors during picking and you won’t need further repacking, or shipping checking. Picked inventory should go on trucks touched only by pickers. Also pick into shipping cartons instead of tote.
2. Rely on system verifications
Design your standard operating procedures to double-verify almost every step in the picking process. You can loosen this later as needed. For example, utilize area’s pick verification flags to have user scan and verify LPN, quantity, item, etc. Count Back or Count Near Zero can also be used to count remaining inventory in a location in-line with picking.
3. Consider different storage strategies
Different storage strategies can boost efficiency within a warehouse. For example, slotting may improve storage intensity, reduce accidents or product damage, reduce congestion and improve retrieval times. Review storage strategies on a regular basis in order to align your practices with seasonal demand.
4. Create a warehouse within a warehouse
Gain tremendous efficiency by grouping together the 20 percent of your SKUs that complete 80 percent of your orders. This cuts down on travel time for your pickers. Be sure, however, that the 80/20 area or zone is properly designed to accommodate high-volume activity.
5. Consider different order picking methods
Zone picking: Each order picker is assigned a specific zone and will only realise order picking within this zone.
Batch picking: An order picker is assigned and picks multiple orders simultaneously, minimizing trips to each location.
Wave picking: A variation of zone and batch picking. Rather than orders moving from one zone to the next for picking, all zones are picked at the same time and the items are later sorted and consolidated into individual orders/shipments.
Consider automation: Order pickers spend about 60 percent of their time walking product or moving product around. Consider an automated solution, such as conveyance, to reduce their extensive travel time. Add workstations with power to eliminate wasted steps.
Eliminate walking and reduce fatigue for more accurate picks: You make more mistakes when you’re tired, and so do your order picking employees. Try to keep them still, not moving and you’ll see faster picks with fewer errors.
The efficiencies are gained because the operator does not have to consume time collecting individual items. Choosing an order picking system depends on any number of requirements such as cost, complexity, the number of customer orders, size and number of items, etc.
Every company has a unique requirement and one order picking solution may suit one business and not another. Determining the requirements will ensure that the most efficient order picking solution is selected.
Efficiency in order picking is critical to the operations as it determines delivery time as well as order fulfillment accuracy. It also plays a fundamental role in ensuring customer satisfaction and in the smooth running of the supply chain.
The concepts such as next-day and same-day deliveries are becoming more and more common for major e-tailers, the speed and efficiency of order picking has assumed extremely important significance. Every second can mean the difference between a promised delivery on time, or not.
Hence, efficient and streamlined order picking is one of the most important functions in a warehouse and needs to be reviewed and revised periodically for optimum performance.
De Koster, R., Le-Duc, T., & Roodbergen, K. J. (2007) “Design and control of warehouse order picking: A Literature Review”. European Journal of Operational Research, 182(2), 481-501.
Erasmus-Logistica warehouse design accessed from http://www.fbk.eur.nl//OZ/LOGISTICA