What is a flow rack?

Flow racks are a type of storage rack. They are characterized by the fact that their storage areas are accessible from both sides. Consequently, the goods can be stored on one side and retrieved on the other. Thus, the use of flow racks favors the Fifo storage strategy (first in, first out), in which the goods that have been stored the longest are also retrieved first. The articles can be stored either in containers or on pallets. In the case of the latter, the rack is then called a pallet rack.

The classical structure of flow racks follows a block arrangement, in which several channels are arranged above and next to each other. The load units in the channels are usually sorted by type and are moved on continuous or discontinuous conveyors, depending on the type of storage equipment. Braking or blocking systems hold the goods in the channel until a load unit is removed. Then the following load unit pulk automatically advances to the channel front of the respective flow rack. As a rule, a distinction is made between electrically and gravity-driven conveyors:

In flow racks with gravity-driven continuous conveyors (e.g. roller conveyors), the stored goods are stored at the higher point and slide by gravity over the rollers to the lower retrieval point. The inclination of the warehouse channels is between 3 and 5%.

In flow racks with electrically operated conveyors, the channels do not have to be inclined. Here, the transport of the stored goods from the storage point to the retrieval point is carried out e.g. by means of driven roller, chain or belt conveyors.

Depending on the design of the flow rack, it can significantly support the picking performance according to the “goods-to-man” principle. It is more beneficial, the smaller the product assortment and the higher the product batch. The use of flow racks also offers other advantages.

Advantages of flow racking:

• applicability of the Fifo principle
• automatability
• high volume utilization, as no additional aisles are needed
• applicable to items with high turnover
• simplified supply chain management

Disadvantages of the flow rack:

• the need for a braking system, otherwise the accumulation pressure and sliding goods can damage the goods in front
• if storage is done without storage aids such as pallets, which could absorb the resulting accumulation pressure, stable packaging for the goods is necessary
• a storage channel can only be loaded with a single article (only one article per channel), which means that the actual stowage volume available cannot be utilized when the capacity utilization is low
• the investment and maintenance costs are comparatively high