Efficiently organizing the incoming goods section of a warehouse is just as important for its productivity as ensuring that it has effective shelf storage systems. After all, if the incoming goods section is not set up correctly, this almost automatically leads to severe disruption in the entire subsequent storage process.
Designing the incoming goods section
In the incoming goods section the goods are identified, checked, and prepared for storage in a multi-stage process. Due to the close link between warehouse logistics specialists and suppliers, information on the incoming goods is generally available beforehand, making it possible to identify them by matching up bar codes or performing a similar task. One essential requirement for simplifying the checking process with a scanner is the establishment of a numbering or bar coding system which can be clearly understood by both parties. If this does not exist, the checks have to be performed manually.
Once the nature and quantity of the incoming goods have been checked, they continue on to quality control. This process sometimes varies considerably – depending on the type of goods delivered – and can range from a cursory check to a detailed analysis of individual goods or the entire delivery.
After the incoming goods have been successfully checked, they are passed on for storage.
Besides the checking function outlined above, the aim of an efficient incoming goods system is to prepare the items for subsequent storage. If mistakes are made in the incoming goods section, this can have costly consequences when the goods are stored and later relocated or retrieved. It is worth considering the sheer impossibility of the task of finding individual goods which have been stored in the wrong place in a warehouse. Poor utilization of the space due to bad planning in the first place can also lead to a lack or waste of storage space.
Errors made while storing goods have an impact on the entire subsequent storage process. Consequently, it is essential that storage logistics specialists have a precise strategy for the efficient storage of goods.
But how can this be organized and structured?
Various strategies can be employed here, depending on the type of goods and warehouse. Essentially, a distinction can be made between two strategies – the allocation strategy and the movement strategy.
The layout of individual functional areas within the warehouse is determined with the help of the allocation strategy. The type of goods located in a particular storage space or zone is dependent on the aim of the individual allocation strategy.
Then there are movement strategies, which govern the use of storage units for storing, relocating, or retrieving goods. The aim of such strategies is to achieve a high degree of efficiency when storing, relocating, and retrieving goods by skillfully utilizing resources within the available warehouse space.
The movement and allocation strategies must be perfectly coordinated with each other by the warehouse management specialists in order to ensure that the warehouse is operated efficiently, because not every movement strategy is compatible with every allocation strategy.
Fast-moving goods concentration
The aim of this strategy is to optimize the distances covered by the order pickers. Storing goods with a fast turnaround time in a central location should reduce the distance employees have to cover and enable them to access the fast-moving goods more quickly. A distinction is made between dynamic and static retrieval of goods.
Fast-moving goods concentration with dynamic retrieval
The goods-to-person principle applies here. The items are conveyed directly to the pickers’ workstation with the help of various means of transport (conveyor belts, vertical carousels, etc.). Items with a fast turnaround time are stored in a way that allows these means of transport to access them as quickly and easily as possible and convey them to the warehouse employee.
Fast-moving goods concentration with static retrieval
The person-to-goods order picking principle is used in this version. Accordingly, the picker removes the necessary goods from the relevant storage space. As such, goods with a fast turnaround time are placed in a central, quickly accessible location within the retrieval warehouse. The disadvantage is that the paths of the pickers may cross when picking up goods located close to each other, thereby hindering one another.
Fixed and free storage space allocation
In the case of fixed storage space allocation, storage space is reserved and kept clear for an item. In contrast, with free storage space allocation, items are placed in any space as soon as it becomes available. In this case, it is completely irrelevant which item was previously stored here or whether the same type of article is stored in a completely different location within the warehouse.
The disadvantage of fixed storage space allocation is that a space has to be kept clear when it is reserved for an article and this cannot be used for other goods. The amount of space required is thus higher with this solution. The advantage is that the storage spaces for the goods can be easily allocated at any time with no support from a software-assisted control system.
Free storage space allocation is more technologically complex, because it requires a warehouse management system to control the flow of goods. The advantage of this solution is that it makes optimal use of the available warehouse capacity, because it is not necessary to block free storage space for items which is perhaps not yet even available. In addition, the storage paths are shorter, because the first available space can always be used.
Equal distribution strategy
Here the goods are distributed across the warehouse in a way which ensures that as many goods of the same type are stored in every location or aisle. The aim is to guarantee balanced distribution of the goods in the warehouse so that capacity is also utilized evenly.
Storage space adaptation
With this approach, the storage spaces are filled with goods according to their capacity to hold them. Small spaces are occupied by low-volume storage units and low stock levels, while larger areas are correspondingly filled with larger goods or units with high stock levels.
Single-article and mixed-article storage
Single-article storage indicates that adjacent storage spaces can only be filled with items that are “identical” (i.e. products of a very similar design, size, etc.). Within the warehouse management software these goods are labelled as “identical articles” with an identification number. With mixed-article storage, on the other hand, the storage spaces are filled with units of various articles. In terms of structure, it is similar to free storage space allocation. There is a greater need for supporting software to be used here as well.
Minimizing partial storage spaces
With any kind of storage, it is possible that the space in one storage location is not sufficient for accommodating all the items in one charge. In such cases the goods must be distributed across several storage spaces, creating partial storage spaces which waste space because the unused areas in such locations cannot simply be filled with other goods. In this case goods from storage units which are not fully charged are always removed first. This is designed to increase the fill level and avoid the use of more than one storage space per item.
Single game strategy
With this strategy the stacker crane picks up a storage unit at the base location and takes it to the designated storage space. The crane then returns to the base to pick up the next storage unit. In these so-called single games the transport vehicles only ever perform either storage tasks or retrieval tasks. The tasks are not mixed.
The advantage of the single game is increased performance when either storing or retrieving goods.
However, there is a disadvantage in that the vehicles spend more time making empty trips (i.e. the return trip to or from the pick-up or drop-off station).
Double game strategy
In contrast to the single game, storage and retrieval tasks are combined with one another here.
In this way, when one item is taken to be stored, another item close to the stored item is then retrieved for the return trip.
The advantage of the double game is that the vehicle routes are optimized, reducing the time spent making empty trips and increasing the efficiency of processes within the warehouse. One disadvantage is the fact that the individual movements take longer. In addition, more precise planning of the processes is needed, which is often only possible with the help of clever warehouse management software.
This strategy determines the routes the stacker cranes should take to the retrieval locations in order to be able to store the goods. The aim here is to visit the storage locations one after
the other taking the shortest possible route in order to minimize the distance covered. Depending on the strategy, the aim can also be to ensure the vehicles are working at full capacity so that as many goods as possible can be transported at once.
The more often goods are moved within a warehouse, the greater the need to relocate individual items as a rule. Storage spaces which were previously very suitable for a particular product can lose their appeal as a result of newly freed-up space for the product elsewhere. This is the case with fast-moving goods, for instance, if space suddenly becomes available close to the picking stations. In addition, newly delivered goods may also require a certain storage location which is already occupied. In such cases, the items stored there must be relocated.
When relocating goods, a distinction is made between:
- Relocation close to retrieval
- Combined relocation and retrieval
- Random relocation
Relocation close to retrieval is a frequently used method for fast-moving goods in particular. It involves the relocated goods being stored as close as possible to the picking or loading station.
Particularly receptive storage units are required for combined relocation and retrieval. They pick up the articles to be relocated and transport them to the location where an item has to be retrieved. While this is also picked up by the transporter, the relocated goods are simultaneously placed in the now free space.
With random relocation the place where the goods are to be relocated is chosen randomly in the same way as with free storage space allocation.
Aisle changing strategy
This is a method which involves collecting storage and retrieval orders and only processing them after a certain period of time.
In most cases, articles have to be retrieved from various storage locations in the course of processing a picking order. This generally means that various aisles have to be visited for one single order. With the aisle changing strategy the orders are collected (formed into batches) and then processed together. In doing so, all the lines of the various orders located in one particular aisle are worked through. As soon as all the lines from all the picking orders have been retrieved from this aisle, it is time to change aisles. The storage unit or the warehouse employee will then move on to the next aisle to retrieve the required items. The primary aim of storing goods with the help of this strategy is to optimize order picking in terms of both time and the distance covered.
Alternative: storing goods in dynamic storage systems
The aim of many of the outlined strategies is to optimize routes and space requirements within the warehouse. In most cases it is assumed that the warehouse has static shelving. However, storage capacity can also be optimized in other ways if storage logistics specialists simply opt to use modern, sometimes fully automatic systems. Thanks to their highly dense design they only require minimal space and can cope with the toughest demands in terms of storage and retrieval efficiency, picking accuracy, and cost-effectiveness when clever warehouse management software is used. Such storage systems include:
Each system must be individually configured to meet the customer’s specific requirements and make optimal use of the available space.
You can find out more about these modern storage solutions here.