Picking – process steps
Picking stands for the compilation of predefined orders from a stock assortment. The process steps that are carried out in the course of picking include, for example, the transfer of the picking order and the provision of the article. These are individual basic functions that do not necessarily have to be used in the same sequence, but can either be omitted or create individual dependencies based on the picking process and its design.
According to VDI guideline 3590 sheet 1, a picking process consists of the following individual process steps
- Specification of transport information (for goods and/or pickers)
- Transport of goods to the staging location
- Staging of goods
- Movement of the picker to the staging location
- Specification of the picking information
- Picking of the items by the picker
- Delivery of the pick
- Confirmation of the picking process or processes
- Transport of the collection unit(s) to the delivery point
- Specification of transport information for the started supply unit(s)
- Transport of the started supply unit(s)
The most important organizational dependencies of the picking processes are examined below. In particular, the operational and organizational structure and the type of picking play an important role in process design.
Process dependencies due to the operational and organizational structure
The way the individual process steps of the respective picking zone are ultimately designed depends, in principle, on the organizational structure and workflow.
- Organizational structure: This is strictly based on the characteristics of the stored items. These include, for example, physical properties such as item dimensions, item volume, item weight; but special properties such as storage temperature and hazardous goods also play a role.
- Process organization: This shows how the actual picking order is processed and which picking types and picking strategies are used: order- or inventory-oriented, parallel or serial, person-to-goods, person-to-person.
The two central processes of a distribution center, storage and picking, are “usually” combined because one does not exist without the other. The process starts with the transport of the goods from the provision of the previous process, e.g. the goods receipt, to the storage and picking area.
Jens Wisser / The process of storing and picking in the context of the Distribution Center Reference Model (DCRM) / CC BY-NC-ND 3.0 DE
Picking: individual process steps in practice
By using a warehouse management system, it can be ensured that sufficient stock is available in the picking area before the start of a picking process. The storage location identification is done via paper lists, terminals, mobile data collection devices or pick-by-voice / pick-by-light.
During the article identification and picking process, the picked article is reported to the inventory management system via the confirmation/withdrawal confirmation. This reconciliation takes place immediately after the scan or, for example, after a completed round. At predefined intervals (hourly, daily), the picked articles are also reported to the ERP system.
In the case of two-stage picking, the items are transferred to a sorter after each round, which distributes the batches to individual customer orders. In the case of single-stage picking, the downstream packing process is no longer necessary, since the parts are picked and packed immediately into the shipping cartons in an order-specific manner.
The individual process steps of a picking process are continuously adapted to new circumstances and optimized. The goal is to achieve short throughput times.
Important: Before, during or even after the picking business process, inventory replenishment often takes place. Replenishment can be precautionary, as needed or necessary due to a shortage in the warehouse (inventory management).
Summary of picking – process steps
The process steps within a commission are clearly defined according to VDI guideline 3590 sheet 1; however, they cannot be considered general. There is no single solution. Different and usually individual infrastructures (storage location management), whether technical, structural or assortment-related, ensure many project-related processes. They are influenced by the following questions, for example: How extensive is my product range? What throughput size do I want to plan for in the future? This in turn raises the questions: At what point do I need manual, mechanized and automated technology? And in the end, the service level for the selected assortment policy determines the picking process – for example, multi-level or single-level.
If you are interested in the topic of picking, then read the articles Batch formation in picking and Single-stage picking – picking without system support.
Teaser image: TUP