The efficient design of incoming goods is just as relevant to the performance of a warehouse as equipping it with effective rack storage systems. If goods receipt is incorrectly designed or not optimally organized, this almost automatically leads to serious disruptions in the entire subsequent storage process.
Strategies for effective storage – Image: Drazen Zigic|Shutterstock.com
Conception of goods receipt
In goods receipt, the goods are identified, checked and prepared for storage in a multi-stage process. As a rule, due to the close cooperation between warehouse logistics and suppliers, preliminary information about the incoming goods is already available, so that identification can be carried out by comparing barcodes or similar. The prerequisite for the simplified check using a scanner is the setting up of a numbering or bar coding that can be clearly interpreted by both parties. If this is missing, the check must be carried out manually.
After the received goods have been checked with regard to procurement and quantity, quality control takes place. This process sometimes varies greatly - depending on the type of item delivered - and can range from a superficial check to a detailed analysis of individual or even all goods.
After successful incoming inspection, the goods are passed on from goods receipt to storage.
In addition to the control function described, the aim of an effective goods receiving system is to prepare the items for subsequent storage. If errors are made when receiving goods, these can have extremely costly consequences during storage and later relocation or retrieval. Just think of the almost impossible task of finding individual goods that have been assigned to the wrong places in a warehouse. Poor use of space due to incorrect planning can also lead to a lack or waste of storage space at the beginning.
Mistakes made during storage affect the entire subsequent storage process. Consequently, a targeted strategy for storing goods effectively is essential for warehouse logistics companies.
But how do you organize and structure this?
Depending on the item or storage type, different strategies can come into play here. Basically, a distinction can be made between two types – occupancy and movement strategies .
The occupancy strategy is used to determine the arrangement of individual functional areas of the warehouse. Which goods are in which storage location and in which storage zone depends on the goal of the respective occupancy strategy.
In addition, there are the movement strategies that decide on the use of storage equipment to store, relocate or remove goods. Your goal is to achieve the highest level of efficiency in storage, relocation and retrieval under given storage conditions through clever use of resources.
In order to operate a warehouse efficiently, the movement and occupancy strategies must be precisely coordinated by warehouse management, because not every movement strategy fits every occupancy strategy.
Strategies for storage: occupancy strategies
Fast runner concentration
The aim of this strategy is to optimize the routes taken by pickers. By storing quickly moving items in a central location, employees' walking distances should be reduced and they should be able to access fast-moving items more quickly. A distinction is made between dynamic or static provision of articles.
Fast-track concentration with dynamic delivery
The principle of goods-to-man picking applies here. The items are moved directly to the employee's workplace using means of transport (conveyor belts, circulating racks, etc.). Items that move quickly are stored in such a way that the means of transport can access them as easily and quickly as possible and send them to the warehouse worker.
Fast-running concentration with static deployment
With this alternative, man-to-goods picking applies. The order picker therefore removes the required goods from the respective storage location. Therefore, with this variant, the items that move quickly are placed in a central, easily accessible location in the staging area. The disadvantage is that the paths of the pickers can cross when picking up the goods that are close to each other and in this way they hinder each other.
Fixed and free storage space arrangement
With the fixed storage space order, storage spaces are permanently reserved and kept free for an item. In contrast, with the free storage space arrangement, items are placed in any space as soon as it becomes free. It is completely irrelevant which item was previously stored in the warehouse or whether goods of the same type are stored in a completely different location in the warehouse.
The disadvantage of the fixed storage space arrangement is that by reserving space for an item, spaces have to be kept free that cannot be used for other goods. The space requirement of this solution is therefore higher. The advantage is that the storage locations of the goods can be determined easily at any time and without supporting software control.
The technological effort is higher with free warehouse management, as its use requires a warehouse management system to control the flow of goods. The advantages of the solution are the best possible use of storage capacity, as it is not necessary to block free storage areas for items that may not even be there yet. The storage distances are also shorter because the first possible free space can always be used.
Equal distribution strategy
The goods are distributed in the warehouse in such a way that as many goods as possible are stored at each location or in each aisle. Your goal is to ensure a balanced distribution of goods in the warehouse and thus an even utilization of capacities.
Storage location adjustment
Here, the storage spaces are filled with goods according to their capacity. Small spaces are occupied with low-volume storage units and small inventory of items, while the larger areas are stocked with correspondingly larger goods or units with high inventory
Single-item and mixed-item space allocation
The item-only space allocation means that storage spaces located next to each other can only be stocked with “same” items (i.e. products with very similar presentation, size, etc.). In the warehouse management software, these goods are marked as “same items” with an identification number. With mixed item occupancy, the storage locations are occupied with units of various items. In terms of structure, it is comparable to the free storage bin order. Here too, there is an increased need for the use of supporting software.
Minimization of partial storage spaces
With any type of warehousing, it can happen that there is not enough space at a storage location to accommodate all of the items in a batch to be stored. In this case, the goods have to be distributed across several storage areas - this creates partial storage areas that waste space because the unused areas in the respective location cannot easily be occupied by other goods. In this case, goods from storage units that are not fully filled are always removed first. This is intended to increase the degree of filling and avoid using more than one storage location per item.
Strategies when storing: movement strategies
Single game strategy
With this strategy, the stacker crane picks up a storage unit at the base location and brings it to the intended storage location. The device then moves back to the base to pick up the next storage unit. In these so-called individual games, the transport devices only ever process storage or removal. A mix of orders is not planned.
The advantage of the individual game is increased performance when storing or retrieving.
However, the longer empty journeys of the storage devices (= return journeys to the pick-up or drop-off station) have a disadvantage.
Double game strategy
In contrast to the individual game, storage and removal are combined here.
This means that the storage of one item on the outward journey is accompanied by the removal of another item stored nearby on the return journey.
The advantage of the double game is the route optimization of the transport equipment, which shortens empty journeys and times and increases the efficiency of processes in the warehouse. One disadvantage is that the individual movement sequences take longer. More precise planning of processes is also necessary, which is often only possible by using sophisticated warehouse management software.
Route strategy
The route strategy determines which routes the stacker cranes should take to the picking locations in order to be able to store the goods. The aim here is to approach the storage locations one after the other on the shortest possible route in order to minimize the travel distances. Depending on the strategy, driving the devices at maximum capacity utilization can also be a goal in order to transport as many goods as possible at once.
Relocation strategy
The more goods are moved in a warehouse, the greater the need to relocate individual items. Storage locations that were previously very suitable for a product can become less attractive due to newly created open spaces elsewhere. This is the case, for example, with fast-moving items when areas near the picking stations suddenly become available. Newly delivered goods may also require a specific storage space that is still occupied. In this case, the items located there would have to be relocated.
The rearrangements are differentiated into:
- Relocation near outsourcing
- Combined relocation and outsourcing
- Random rearrangement
Relocation near removal is a method often used, especially for fast-moving items, in which the goods to be relocated are stored as close as possible to the picking or loading station.
Particularly high-capacity storage equipment is required for combined relocation and retrieval. These pick up the items to be relocated and transport them to the location of the item to be removed. While this has also been picked up by the transporter, the goods to be relocated are simultaneously placed in the now free compartment.
With random relocation, the location to which the goods are to be relocated is chosen randomly, as with free storage location ordering.
Gear change strategy
This is a method in which storage and retrieval orders are collected and only processed after a certain period of time.
In order to process a picking order, items usually have to be picked from different storage locations. As a result, different aisles would usually have to be approached for a single order. In the gear change strategy, orders are collected (forming so-called batches) and then processed together. All positions of the various orders relating to a specific aisle are processed. The gear change occurs from the moment after all positions of all picking orders have been approached in this gear. The storage device or warehouse worker then moves to the next aisle to remove the required items. Storing with the help of this variant of warehouse management is primarily aimed at path- and time-optimized picking.
Alternative: storage in dynamic storage systems
Many of the strategies described aim to optimize travel routes and space requirements in the warehouse. This is usually based on a static shelving system. However, storage capacities can also be optimized in other ways; simply by warehouse logisticians deciding to use modern, partly fully automated systems. Due to their highly compact design, they only require a small amount of space and, using their sophisticated warehouse management software, meet the highest demands in terms of efficiency in storage and retrieval, picking accuracy and cost aspects. These storage systems include
- Vertical and high-bay warehouses
- Carousel warehouse
- Shuttle systems
Each of the systems must be individually configured to suit the customer's requirements and spatial requirements.
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