The put-to-light order picking system speeds up picking through the use of light displays

Put-to-light order picking technology

10 May 2022

Put-to-light is a semi-automated order picking solution that improves operator throughput when placing products in containers by means of light devices. 

Designed to maximize efficiency, these semi-automated picking solutions — which also include pick-to-light, voice picking systems and RF scanners, are your best bet for reducing errors in order processing.

What is put-to-light?

Put-to-light solutions, also known as sort-to-light or pick-to-light in reverse, employ a set of LED light devices that guide operators in terms of which location to leave the goods in and how much product to put in each package, box, or drawer on the shelf. The main aim of put-to-light is to sort products in the boxes that will be used to send orders in a way that’s both agile and error-free.

The put-to-light system can be installed on picking shelves or on carts for efficient pick-to-cart operations. Put-to-light works as follows: each container is outfitted with an associated light. During the order preparation process, the display on the relevant location lights up, showing the operator where to leave the goods and in what quantity. 

Put-to-light systems are connected to a warehouse management system (WMS), which coordinates the light displays, automating decision-making for operators. In other words, the WMS shows the operators which box to deposit the goods in and indicates on the LED display the number of units to leave of the SKU in question. The software is also connected to the RF scanners used by the operators to read the products to be sorted. 

Put-to-light systems are often implemented to minimize errors in batch picking, whereby the operator puts different quantities of a single SKU in several orders. To speed up the supply of goods to pick stations where orders are sorted, a conveyor for boxes can be set up to ensure continuous flows of stock with the put-to-light system.

Operators follow the instructions on the put-to-light display to place the products in their corresponding boxes
Operators follow the instructions on the put-to-light display to place the products in their corresponding boxes

How does put-to-light work?

The put-to-light semi-automated picking system is connected to the WMS to coordinate the different light displays on each location or container, as well as the tasks of the operators. Using RF scanners, the warehouse pickers scan the product label, and the software then guides them in placing the items where they belong.

The containers or picking shelves are equipped with a display, connected to the WMS, that tells the picker how many SKUs to place in each box. Once this action has been performed, the operator presses the button next to the display, confirming to the software that the task has been completed correctly. The display light is then turned off, and the picker continues to place goods in other locations or returns to the area where the stock is kept to scan another item.

Differences between pick-to-light and put-to-light

The main difference between the semi-automated pick-to-light and put-to-light systems lies in the function of the operator during the process. While in put-to-light the operator places the product in boxes or drawers, pick-to-light consists of removing the quantity of goods indicated by the containers. 

The two picking systems are often confused because both feature light displays on picking shelves, and they have the same purpose: to speed up order fulfillment and reduce errors. Both systems also require an advanced software to manage the light displays and RF scanners used by the operators. 

Advantages (and disadvantages) of put-to-light

The semi-automated put-to-light system offers several advantages. These include:

  • Agility in order picking. Put-to-light expedites the simultaneous preparation of multiple orders. The operator sorts the items into the different containers, depositing the exact quantity of goods indicated by the display. This agility in picking shortens order cycle times, resulting in more efficient logistics service. 
  • Fewer mistakes in picking. Both put-to-light and pick-to-light systems automate decision-making for warehouse pickers, minimizing the possibility of picking mistakes due to manual management. 
  • Optimization of operator travel. This semi-automated picking system simplifies the order preparation process because operators can complete one or more orders with the necessary products on a single run through the warehouse. 

Nevertheless, the put-to-light system does have some drawbacks. This picking solution is efficient when sorting an item into several orders, i.e., when each operator picks a product and distributes it into the different containers or locations based on the quantity shown on the display. In warehouses with many SKUs or products with varying turnover rates, this system might not be the most effective for optimizing order picking. 

Moreover, even though it automates operators’ decision-making, put-to-light depends on the execution of tasks by warehouse pickers, meaning there's always a minimal risk of error. Automating the pick stations by installing automated solutions such as pick and place eliminates errors and increases the number of picks per hour. 

Example of put-to-light: Aghasa Turis

The semi-automated put-to-light solution is charged with streamlining order picking and minimizing goods handling errors. This was precisely why industrial supplies business Aghasa Turis implemented this system in its facility in Leganés, Spain. 

Easy WMS, our company’s warehouse management software, acts as the brain of the facility. As the stock from the automated storage and retrieval system (AS/RS) arrives at the pick stations, on a screen, Easy WMS shows the operators how many items to pick. To facilitate product sorting, Mecalux installed put-to-light devices, which show the operators the boxes in which they should leave each item, as well as the required quantities of stock. 

“Thanks to the help of Easy WMS and the pick/put-to-light systems, in this first phase, we’ve increased our picking speed by 15%. With the adjustments being made and the start-up of the second phase, we’re going to triple our order picking capacity,” says Darío Alonso, General Manager at Aghasa Turis.

Aghasa Turis has sped up order picking with put-to-light devices
Aghasa Turis has sped up order picking with put-to-light devices

More agility, fewer errors

Put-to-light is a semi-automated system that ensures efficiency in order processing. It can also be combined with conveyors and other automated solutions such as AS/RS for boxes. 

Order picking is one of the most important and complex operations in a warehouse. It’s also the one logistics managers devote the most effort to. The automation of movements and digitization of management are technology solutions that foster efficient, error-free picking. Want to leverage the latest technology to get the most out of your logistics activities? Don’t hesitate to contact us — one of our expert consultants will offer you the best solution for your needs. 

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