Picking stands for the combination of predefined orders from a warehouse assortment. The process steps that are carried out during picking include, for example, transferring the picking order and retrieving the article. These are individual basic functions that do not necessarily have to be used in the same sequence. Based on the picking process and its design, they are either omitted or create individual dependencies among themselves.
According to VDI Guideline 3590 Page 1, a picking process consists of the following individual process steps
- Specification of transport information (for goods and order pickers)
- Transport of the goods to the place of staging
- Provision of the goods
- Movement of the picker to the staging location
- Specification of the withdrawal information
- Removal of the articles by the order picker
- Delivery of the withdrawal
- Confirmation of the withdrawal operation(s)
- Transport of the collection unit(s) for delivery
- Specification of the transport information for the partial staging unit(s)
- Transport of the partial staging unit(s)
In the following, the most critical organisational dependencies of the picking processes are highlighted. In particular, the organisational and operational structure as well as the type of order picking play an important role in process design.
Process dependencies through structure and process organisation
The design of the individual process steps of the respective picking zone depends in principle on the organisational structure and the workflow.
- Organisational structure: It is strictly oriented to the characteristics of the stored articles. These include, for example, physical properties such as article dimensions, article volume, article weight, but special properties such as storage temperature and hazardous goods also play a role.
- Process organisation: It shows how the actual picking order is processed and which picking types and picking strategies are used: order- or article-oriented, parallel or serial, person-to-goods, person-to-person.
The two central processes of a distribution center, warehousing and order picking, are usually combined, since one does not exist without the other. The process starts with the transportation of goods from the staging area of the previous process, for example, goods receipt, to the warehouse and picking area.
Jens Wisser / The Storage and Picking Process within the Distribution Center Reference Model (DCRM) / CC BY-NC-ND 3.0 DE
Order picking: individual process steps in practice
The use of a warehouse management system ensures that sufficient stock is available in the picking area, even before the start of a picking process. Paper lists, terminals, mobile data recording devices or pick-by-voice / pick-by-light indicate the location in the warehouse.
In the course of the item identification and removal, an acknowledgement/removal confirmation for the withdrawn article is sent to the inventory management. This comparison takes place directly after the scan or, for example, after a completed tour. In previously defined intervals (hourly, daily), the picked articles are also reported to the ERP system.
In the case of two-stage picking, after each round, the batches are handed over to a sorter, which distributes them to individual customer orders. In the case of single-stage picking, the downstream packing department is no longer required, as the parts are picked directly into the shipping cartons according to the order and then packed.
The individual process steps of picking are continuously adapted and optimised to new conditions. The aim is always to achieve short throughput times.
Important: Before, during or even after the business process order picking, the goods are often replenished. Replenishment can be necessary as a precaution, as required or due to a shortage in the warehouse (inventory management).
Summary picking – process steps
According to VDI guideline 3590 sheet 1, the process steps within a commission are clearly defined; however, they cannot be regarded as generalistic. There is no single solution. Different and usually individual infrastructures (storage location management), whether technical, structural or assortment-related, ensure many project-related processes. The following questions define the different layouts: How extensive is my product range? With what throughput size do I want to plan for the future? In turn, the following questions follow: When do I need manual technology, when do I need mechanised technology and when do I need automated technology? In the end, it is the service level that determines the order picking process – for example, multi-stage or single-stage – for the selected assortment policy.
If you are interested in other aspects of the topic picking, we recommend reading the articles Batch formation during picking and Single-level picking – picking without system support.
Teaser picture: TUP.com
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