Warehouse picking: Solving Common Errors with a WMS



What is warehouse picking?

Warehouse picking is a crucial process in the distribution center for order preparation. It significantly influences the productivity, speed, and accuracy of your operation, thus directly impacting costs and the service level.


This process involves selecting and picking the products requested by customers for each order. A good Warehouse Management System (WMS) offers various picking processes including:


  • Conventional Picking:We An order is selected and navigated through the distribution center aisles to pick the included products. At the end of the route, the order is left on a packing table or at a loading dock. It is a similar process as shopping at a supermarket.

  • Cluster Picking: Several orders are selected and through conventional picking, are placed in a cart or vehicle with separate compartments. The products are gathered from each location for all orders and placed in the appropriate container.

  • Reverse Picking or Put to Store: Locations have been defined for each order or customer, and the aisles are traversed in a vehicle with one or more products. The required products are placed in the location for each order or customer.

  • Pick and Pass:When dealing with a large number of products or SKUs (Single Keeping Units) and the products are difficult to distinguish (e.g., in pharmaceutical retail), sorting zones with a small number of SKUs are defined for handling. The container passes from zone to zone to be filled with the products the operators require corresponding to each location.

  • Bulk Picking: One or several products are picked from their corresponding locations in a consolidated manner for multiple orders. Then, the required products are placed in areas designated for each order or customer. It is a combination of conventional picking and reverse picking.

  • Cross-Docking: Products are picked at the receiving dock and sent directly to locations designated for orders or customers without going through a storage or stock area.


Market-required delivery times are getting shorter, demanding increased order processing speed in distribution centers and greater flexibility to prioritize customer orders, using the most appropriate combination of picking processes for each order.



What are the main errors in warehouse picking?

Errors in picking processes directly impact the productivity and service level of the distribution center and the entire supply chain. If these errors are not identified within the facility, they reach the customer, generating high-impact costs and inconveniences.


Here are some of the most common errors during warehouse picking:


  • Human errors in product selection: Incorrect products or quantities are chosen when picking.

  • Human errors in product placement: Products are placed in the wrong location, causing the picker to take the indicated location's product, which is incorrect. Lack of organization and location control in the distribution center often leads to this error.

  • Picking is done manually with a paper list, leading to more errors, as there is no system-based confirmation of the correct product.

  • Multiple individuals perform picking, generating different packages or containers that are not adequately consolidated during packing or shipping.


What is the impact of warehouse picking errors?

If a picking process is inefficient and needs system control, will likely introducing a customs checkpoint at the exit of the distribution center may be needed to verify picking accuracy. However, this process incurs additional costs and time and only partially eliminates errors. Furthermore, for each identified error, there is a need for reorganizing the wrongly picked product and retrieving the missing product separately to complete the order.


If warehouse picking errors are not caught at the distribution center "customs" checkpoint, additional costs will be incurred including round-trip product transport, shipping, and the entire reverse logistics process. Moreover, a more impactful error creates a poor buying experience for the end customer, who will have plenty of reasons to be upset.



Why are there so many errors in warehouse picking?

Warehouse picking primarily involves human operators, and the main problem arises when these operators need to familiarize themselves with the thousands of SKUs available, making it challenging to identify the merchandise to pick quickly.


Another issue with picking is that operators often place or pick merchandise from incorrect locations because there is no system to help validate where they store or retrieve it.



A WMS helps reduce warehouse picking errors by:

  • Guiding and directing the operator with the logical sequence for picking merchandise. This sequence should consider merchandise slotting or arrangement. This ensures that picking is as direct as possible to how products are loaded and delivered, beginning with heavier items at the bottom of a pallet and ending with delicate merchandise to prevent damage.

  • Helping the picker locate the correct merchandise by directing them to pick locations. When inventory runs low, the system generates a replenishment order for another worker to support the picking line. This ensures there is always merchandise available, making the processes more efficient.

  • Ensuring that the merchandise the operator picks is correct, using confirmation methods like barcodes, QR codes, a verification digit (voice picking), or lights indicating the location and quantity (pick to light).

  • Ensuring the operator places the picked merchandise in the correct location for the specific order or customer.

  • Aiding in eliminating paper usage by guiding a mobile device. It guides the picker throughout the process and can only be closed when the system notifies that the task is completed, reducing errors.


In conclusion, a WMS helps manage the overall warehouse operations:

  • Tasks and orders are automated and monitored, maximizing operators time to task.

  • Logistics are optimized within the warehouse so operators will cover the shortest distance possible to pick up the assigned orders.

  • Orders can be processed more quickly, and those critical for service level or final destination are prioritized, meeting service levels, purchase promises, and delivery commitments.

  • Merchandise in the distribution center can be efficiently picked for the end customer or store, with punctuality and without errors.

Remember that reducing warehouse picking errors will improve the quality of service provided to end customers.


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