Order picking

Order picking: Definition

Order picking is an activity in the warehouse, in which the required items for a customer or production order are provided and made ready for dispatch by the responsible employees, also called pickers. Picking is performed in single or multiple stages and is transmitted in the form of pick lists or electronic terminals. The process accounts for more than 50% of a distribution center's operating costs, according to industry reports, and is one of the most complex tasks in the warehouse.  

As order picking has a direct impact on customer satisfaction, company reputation and profitability, companies are constantly working to optimize the process. One important metric in this regard is picking performance. It indicates how many items an order picker manages per hour. In this way, it is possible to assess how well the warehouse is functioning and how efficiently it is working. The aim is to maintain a material flow that is as seamless as possible.  

Order picking process

The picking can be done manually by employees or mechanically by robots. In manual picking, the process is as follows: 

• First, the picker receives a picking order on which all required goods are listed. 
• In the manual man-to-goods principle, the warehouse employee walks from the starting point to the first product, then to the other products, and finally back to the work area to pack the order. 
• At the respective storage location of the items, the picker removes the goods. It does make a difference whether the goods are stored at ground level, low to the ground or several meters above the ground because it depends on how long the picker needs to remove the goods. In addition, the error rate is particularly high in this phase - for example, if the pickers are in a hurry and accidentally remove the wrong items. 
• In the final phase, the items are checked, packed and labeled. Then the order is transferred to the shipping area and a delivery bill is created. 

Differences in the process can arise, for example, due to different picking methods, which are described in the next section. 

What types of picking exist?

Basically, a decision is made between the man-to-goods and goods-to-man methods:  

Goods-to-Man system 

Stacker cranes ensure that the articles are transported directly and automatically to the picker at the picking location. After he has picked the items, the totes are transported back to their storage location. This saves time and money because there is no more walking and the employee remains permanently in one place. In addition, the error rate is low due to automation and a high picking performance can be fulfilled. However, the acquisition of such systems is very cost intensive. In addition, goods-to-man picking can lead to warehouse downtime due to machine failure. For this method, a warehouse management system is required in addition to the conveyor technology. 

Man-to-goods system

The employee must walk to the storage location of the goods and pick them manually. Support is provided, for example, by forklift trucks or mobile terminals. If the picking paths are optimized, high performance can also be achieved here. In general, this method is particularly suitable in warehouses with small order sizes and goods with low weights. 

Various methods are used for manual picking:  

• Pick-by-Light: For picking, the picker no longer needs packing lists, but is shown the relevant storage compartments and the quantity to be picked via special displays or light signals. 
• Pick-by-Voice: With this method, orders are transmitted to the order picker's headset via radio or Wi-Fi. This way, he has both hands free to pick the items.  
• Pick-by-Scan/Pick-by-MDE: A barcode scanner is used to establish a link to the system. The list is displayed to the picker on a PDC and he can confirm the picked articles directly. Missing quantities can also be entered. 
• Pick-by-vision (augmented reality-supported picking): special data glasses display the information in the employee's field of vision during picking. 

Single-stage and multi-stage picking

In single stage picking, each customer order is carried out in a single operation. This type of picking is used especially in small warehouses.  

With two-stage or multi-stage picking, several pickers can process the orders at the same time, because the orders are broken down into partial orders. The picking time is reduced due to the shorter distances and fewer accesses to articles.