The pouch sorter (or bag sorter) is a type of logistical sorting and distribution system. A so-called (hanging) pouch sorter system makes it possible to transport hanging and flat-packed goods fully automatically on the same system – classic cardboard goods are not uncommon either. There are no breaks in transportation, as there are in conventional systems, for example, due to handover to the stacker.

A pocket sorter is used primarily in the areas of returns and picking (mainly fashion). However, there are also pocket sorter systems that are used simultaneously as a storage or buffer system (see buffer functions in practice). The warehouse management system (WMS) or the material flow control system routes the respective bags, including the goods, fully automatically to the packing station – thus eliminating the need for classic picking for bag-compatible goods. The item rotates in the system until it is discharged by the WMS for processing – provided that the goods can be stored and transported in non-rigid conveyor elements. In normal cases, folded and hanging garments should not remain in the pockets for more than three days. On the one hand, it should be noted that a T-shirt or shirt, for example, can be scrunched up and create up to seven centimeters of stowage length at the bottom of the pocket; on the other hand, fast-moving items are required in the pocket sorter for planning purposes. Long-term storage in the pocket sorter is therefore taboo.

Buffer function in practice

The high scalability of the so-called dynamic buffer* is particularly noteworthy. Frequently requested items and returned items are stored in the pockets and do not have to be picked manually. Each pocket, equipped with an RFID chip or barcode, is linked to exactly one physical item (see the linked video). When processing customer orders, items are first accessed from the dynamic buffer. If the buffer does not contain all the items in the customer order, these are manually added to other pockets, if this makes sense from a conceptual point of view. Subsequently, all pockets are then transported fully automatically to the packing station and ideally also merged directly by the sorter and forwarded to the shipping department.

Bag sorter: space and time savings

The advantage of a bag sorter is that it saves space due to the vertical bag arrangement. In contrast to other systems, you can store much more densely. In addition, a bag sorter is often installed directly under the ceiling of a distribution center, thus saving or freeing up valuable floor space. Another decisive factor is the automatic single-item access to each item.

Providers also promise a space requirement of up to 25 pockets per meter. However, this specification depends on the assortment stored in each case. It should also be noted that, as a rule, only one item can be transported per pocket for process-related reasons.

Important: The number of packing stations depends on the individual processes and process times at the individual stations. In figures; when using 7,500 bags, an average of about ten loading stations and 30 packing stations is expected in typical applications. Depending on the manufacturer, current bag sorter systems can typically handle about 10,000 cycles per hour, making it easier and faster to process short-term marketing campaigns and seasonal peaks. This results in a usable operational performance of the 7,500 bags per hour mentioned above; also because not every cycle can be used – always per strand and usually in parallel (see the video). The time saved naturally depends on the individual processes that take place after the quality inspection (returns processing) at goods receipt or at the returns receipt.

Example: Classic work steps in the restocking of returns

• Quality inspection
• Pre-sorting for the respective picking zone
• Transport to the picking zone
• Transport to the storage location
• Storage
• Marriage with the storage location (storage location management)

Work steps for the pocket sorter

• Quality inspection
• Pre-sorting (decision “pocket-ready – yes or no”)
• Transport to the filling station
• Storage / pocket

Important: With the pocket sorter, the classic picking processes are initially omitted. The employee merely decides after the quality inspection whether the goods are “pocketable or not”. If the goods are not pocketable, they are transported and processed via the conventional conveyor system. However, goods that are not in stock can be picked manually from the warehouse and fed to the pocket sorter. At the end of a season, the buffer should also be cleared of the seasonal assortment. This usually happens automatically. These goods must then be picked from the pockets and returned to the warehouse via the conventional storage process.

Conclusion: pocket sorters

A pocket sorter is suitable for goods that only remain in the warehouse for a short time. This is one reason why a pocket sorter can also be used as a buffer. Thanks to the buffer function, only some of the returned goods have to be returned to the warehouse – fast movers can be requested directly from the buffer.

Where, for example, a high volume of returns (multi-channel and omni-channel – generally e-commerce strategies) is registered, it is usually worthwhile to use a combination of pocket sorters and conventional conveyor and storage techniques.

For more information on material flow, see also material flow simulation and transport management.

Image gallery pocket sorter: with kind permission of arvato Bertelsmann SCM Solutions

* Case Study – Logistics Growth in the Pocket, Arvato Bertelsmann