Storage means the deliberate interruption of the operational flow of materials , i. That is, there are deliberately formed stocks . Warehousing requires a warehouse , i. H. a room , a building ( logistics property ) or an area in which goods can be stored and is a central theme of inventory management .
Subject of storage
Storage objects can be
- Tools (tool issue separated into capital goods, for example machines , and consumables such as office supplies );
- Means of production (internal warehousing / logistics with external suppliers);
- Products ( finished or semi-finished products ) (warehouse, order picking, shipping department, external shipping company);
- Operating materials that are consumed but not included in the product;
- Raw and auxiliary materials that go into the product and means of transport that are only kept available for the transport of products and mostly return.
Personnel is not stored, but at most kept internally or externally. Therefore, the characteristics, strategies and optimization methods of storage are not applicable to personnel.
Functions and tasks of warehousing
Basically, warehouse logistics distinguishes between the following warehouse functions or tasks:
- Backup function
- Bridging function
- Finishing function
- Transformation function
- Speculative function
The backup function comes into play when insufficient information is available in the company about future quantity requirements, delivery times and requirements. This can be the case in particular with products that are subject to seasonal fluctuations - and thus delivery bottlenecks - but which actually have to be available at all times.
In order to guarantee this constant availability, sufficient buffer quantities are defined by iron stocks , minimum quantities and reporting stocks , which are calculated from the delivery time of a possible order quantity at the procurement sources. As a result, the required quantities are always kept available - in at least sufficient quantity and quality . (see section on stocks )
With the provision or assortment function , storage contributes to a range in the assortment . In this respect, the supply function supplements the balancing function, as it bridges the parts of the range where there is a discrepancy between the quantities of procurement and sales .
If the procurement quantity is greater than the production quantity , the material that has not yet been used for production is stored by the compensation function . A warehouse is used as an intermediate storage facility in order to keep the material flow stable in the volume flows. The bridging function also serves to prepare finished goods for delivery before they are delivered. A storage in the sense of the bridging function can also take place dynamically if, for. B. Goods on continuous conveyors (treadmills, taxiways, etc.) are parked or moved there in waiting loops.
The refining function is also called the warehouse's production function, which only enables subsequent processing. The refinement function describes storage that leads to the desired change in the product and is therefore part of the production process. This is particularly true of
- Drinking alcohol ( rum , wine , whiskey etc.)
- Fruits (including bananas )
- Animal products ( honey , cheese , leather , ham, etc.)
In particular in the warehouses of trading companies , the warehouse performs transformation tasks; for example, the goods are transferred to salable packaging and labeled. A supplementary sorting task can also be defined here, in which non-salable goods are sorted out and disposed of.
Reasons for the speculative function of storage can be foreseeable extreme price fluctuations on the procurement market or particularly low cost prices . In addition, you can speculate with stock items by ordering large quantities and receiving discounts . However, if the price of the goods falls, this can also have a negative effect. B. in hardware .
The warehouse fulfills a size-degression function because it enables orders for several items and can thus reduce the order costs per unit.
The environmental protection function includes
- Return and collection of reusable packaging and recyclable materials as part of the "Dual System" (DSD)
- Return and collection of old products for reuse or further use, recycling or disposal
- safe storage of hazardous substances
In particular, it is also stored for training purposes; camps are set up that have no function other than training; the pieces stored in it are then neither used for production nor for trade.
The camp can be classified according to various criteria; The following aspects are among the most important distinguishing features (with overlaps):
- according to the types of goods to be stored :
- Consistency (solid, liquid, gaseous)
- Material type ( wood , metal , plastic , glass etc.)
- Weight ( heavy cargo )
- Volume (small, large, bulky)
- Temperature (cold storage)
- Quantity (low, medium or high stocks)
- Storage and consumption units (piece, pair, dozen , increments of 10, 100 etc.)
- Storage condition (e.g. packed , unpacked, stackable)
- Value (low or high quality; important in the ABC analysis )
- Sensitivity ( weather or climatic resistance, need for care and maintenance, perishability)
- Dangerousness (pointed, sharp, poisonous, corrosive, radiant, environmentally hazardous)
- Type of use ( raw materials, consumables and supplies )
- Shelf life (limited or unlimited)
- Turnover frequency ( fast- moving items , goods rotation , classification according to ABC analysis )
- Operating mode of the company
- Industrial company
- Sales warehouse
- Distribution warehouse
- Distribution warehouse (e.g. hubs in freight forwarding)
- Inch bearing (Verwahrlagerung)
- Warehouse location
- Bearing construction
- Warehouse owner or form of administration
- Storage technology
- Floor storage
- Storage facilities
- Pallet rack
- Drive-in shelf
- Flow rack
- Cantilever rack
- Honeycomb and cassette shelving (for long goods or flat goods)
- Mobile shelving
- Carousel (horizontal circulation)
- Paternoster storage (vertical circulation)
- Tower rack (for flat or long goods)
- Slide-in shelf
- Channel rack or tunnel storage
- Automatic container racks or automatic small parts warehouse
- Closet storage
- Shelf storage
- Storage means of transport
The aim of planning a warehouse must be that it can fulfill the required warehouse function; in particular that in the sense of the security function z. B. Production sites can be continuously supplied with the required materials. The warehouse planning refers to the planning of the warehouse organization, the warehouse and transport technology, the storage units to be stored and the warehouse layout. Systematic warehouse planning should, among other things, reduce storage costs. In addition, warehouse planning can help increase the level of mechanization and automation.
When choosing warehouse locations, it must be decided whether the warehouse will be managed centrally or decentrally. When deciding on the degree of centralization, the spatial aspect is often decisive:
Central warehousing means the spatial combination of all warehousing functions and all stored goods under uniform management. The advantages that result from the central storage are a simplification of the acceptance of goods, care, maintenance, inventory determination and inspection. Other points are the low capital commitment of current assets , lower inventories and lower space costs .
With decentralized warehousing , the input materials are stored at the location of the user in the form of intermediate storage (buffer storage). The main advantages of this storage method are the higher flexibility, the more precise disposition of the individual materials in the production areas and the shorter transport routes .
With fixed storage location allocation , fixed storage locations are provided for each article, which are reserved for these articles only ("same to same"). The advantage lies in the simple determination of the storage space. Due to the fluctuating stock levels for each item over time, part of the permanently allocated storage space is not used, which leads to poor utilization of the storage capacity.
With the dynamic storage location allocation (open warehouse system) , the articles are stored in a free storage location. Storage takes place at will or according to specified parameters. One advantage of this method is that if faults occur in one storage aisle, for example, the same material can be removed from another storage aisle. The greatest advantage, however, is a very high utilization of the storage capacity. However, in order to guarantee later access to the stock items, the storage locations must be precisely documented. This can be done with a storage compartment card , which then stores the data in the EDP system, or the storage location is specified by a warehouse management system. In the chaotic storage of hazardous materials (. Eg certain adhesives, chemicals) are restrictions and Storage of incompatible materials to be considered so dangerous reactions are avoided in case of incidents.
An inventory as such is the quantity of a good in the warehouse at a certain point in time. The following special stocks are important:
- Minimum stock
- Reorder point (order point)
- Maximum or maximum stock
The minimum stock (in practice also safety stock or outdated iron stock / reserve ) is the stock level that must not be fallen below in order to be able to maintain the readiness for delivery even in emergencies. The minimum stock varies according to the material and / or supplier. It generally covers the risk of the supplier failing to meet deadlines or quality. When the reorder point is reached through withdrawals from the inventory, a message to the purchasing department to replenish the inventory - by placing an order - is triggered during the automatic disposition . The reorder point thus determines the due time of the requirement. See also: sediment analysis , ordering policy
optimal inventory = the optimal inventory enables a smooth operation and causes low storage costs. The optimal stock level must be coordinated with the optimal order quantity.
As part of the cumulative quantity is the minimum stock and maximum stock of a bearing dynamic sizes of storage using lead time are recalculated. Because if the material requirement in production decreases (increases), then the demand in the warehouse also decreases (increases) and can even be "zero". Therefore makes the cumulative quantity principle a fixed reorder no sense. However, in order to discover possible errors or to avoid possible bottlenecks, an upper and lower reporting limit can be defined; As soon as this is reached, an alert is issued so that it can be checked whether the under-stock / over-limit is correct or whether there is an error (e.g. in the data acquisition or the requirement calculation).
With the FIFO principle ( First In - First Out ), the goods stored first are also retrieved first.
With the Lifo principle ( Last In - First Out ), the last stored supplies are removed first. As a rule, this is undesirable, but sometimes inevitably the consequence of the bearing design.
In the food sector, for medicines or sterile goods, storage is also carried out according to the best-before date ( First Expired - First Out , FEFO), as this can also differ from the storage sequence.
The average inventory indicates how high the inventory is on average over the course of a fiscal year. It can be calculated as a quantity or a value.
If only a company's published balance sheets are available, the following, less precise formula is often used. The formula only considers the stocks available on the balance sheet date and is therefore very inaccurate. It is mainly used by external analysts in their balance sheet analysis .
The inventory turnover rate indicates the ratio of consumption / time unit and the average inventory, and therefore shows how often a warehouse has been completely filled and emptied within a certain time unit. The key figure can be determined in terms of quantity or value. Low values mean that the material remains in the warehouse for a long time and is an indication of high safety stocks. These have a negative effect on the capital commitment .
Average storage time
The average storage duration provides information about the situation in the warehouse and the development of the capital commitment in the warehouse. It shows how long the stocks - and thus of course the capital required for them - are tied up in the warehouse on average. The shorter the storage period of a product / component, the better, since storage causes running costs, requires space and this can make the products more expensive.
The storage interest rate indicates what percentage of interest the capital tied up in the average inventory costs during the average storage period.
(10 % · 200 Tage) / 360 Tage = 5,55 % für 200 Tage
The storage interest or the storage interest indicate how much interest the entrepreneur misses during the storage period. The capital is tied up in the warehouse and therefore cannot be invested with interest. The storage interest rate is used to calculate the storage interest.
Lagerzinsen = Wert des durchschnittlichen Lagerbestandes · Lagerzinssatz
5000 € · 5,55 % = 277,50 € für 200 Tage
Stock range / readiness for delivery
The days' supply indicates how long the average inventory will last with an average consumption per period. The days' supply can also be calculated for a specific key date (e.g. start of a quarter).
20 Stück / 0,117 Stück pro Tag = 171 Tage
Durchschnittlicher Verbrauch pro Tag = (Wareneinsatz / 360 Tage) 42 Stück / 360 Tage ~ 0,117
The stocking quota indicates the ratio of the number of stocked to the total number of procured material items.
Stock quota = number of stored articles / total number of articles procured
Storage utilization rate
The degree of storage utilization shows the ratio of space used to available space. The indicator reveals both bottlenecks (overcrowding) and insufficient utilization (overcapacity).
Flächennutzungsgrad = (genutzte Lagerfläche / verfügbare Lagerfläche)
Raumnutzungsgrad = (genutzter Lagerraum / verfügbarer Lagerraum)
Delivery readiness level
The service level of the bearing can in the average time period to be the material (external service level), or measured by the average time between the instruction to paging and the location output (internal service level) between the demand request and the provision.
The capital commitment is a key figure for the non-liquid assets in a company. For example: stocks, machines and systems.
Key figures of the means of transport use
Additional descriptive storage parameters
Key figures are to be created for the company in coordination with the management and management. Insignificant key figures from a company perspective should be omitted. It is important to derive or specify budget figures from the key figures so that deviation analyzes can be produced and corrections can be initiated.
Essentially, according to Hartmann, Hoppe and Schwalbach, the following extended storage parameters can be added to the storage key figures mentioned above. These warehouse parameters are used to describe your own warehouse and are less suitable for comparison with other companies or warehouses.
- Value in euros of stagnant stocks with a turnover of less than two per year
- Consignment stocks at suppliers in euros and as a percentage of the total stock
- External inventories of the suppliers in-house in euros
- No longer usable inventories in euros and percent
- Age structure in percent of the supplies per time class
- Share of new materials and discontinued materials
- Sediment parameter : the part of the stock that has not been moved over a certain period of time.
- Incoming value parameters : Valuated stock = delivered quantity × valuation price.
- Parameter security cushion: formed from the key figures range of the average access and range of the average stock upon access .
- Safety stock parameter : Comparison of the value of the mean stock at access to (quotient of mean stock at access and safety stock, which should be approximately 1).
- Parameter cost size: range of mean access and value of mean access compared.
- Analysis according to the volume of the parts: division of the materials into large-volume, medium-volume and small-volume parts.
Approaches to warehouse, inventory and supply analysis
Conflicting goals in warehousing
Based on Hartmann, corporate development and management must face a changed market landscape. These include ever shorter delivery times, higher demands on readiness to deliver, greater flexibility on the part of suppliers, more product diversity, shorter product life cycles and fundamentally changed requirement profiles for suppliers due to globalization and offshoring. The way to do everything by setting up stocks inevitably leads to high capital commitment and decreasing liquidity. Further disadvantages of excessively high inventories result from the risk of changes in products, the spoilage of the products (e.g. food) and the costs of storing and managing the inventories.
The areas of tension arising from the departmental interests can be compared below:
- Procurement objective:
Security of supply for large order lots, safety stocks
Requirement: Reduction in stocks of
small order lots, short procurement times
goal : uniform utilization of capacities, large production batches , buffer storage
Requirement: Stock reduction,
capacity reserves , batch size 1, needs-based production, production and supply according to the production plan
- Sales targets: Fulfillment of customer requirements,
extensive range, high level of readiness for delivery
Requirement: Reduction in stocks of
small ranges, fewer product variants
Determination of the necessary inventory
The industry comparison
In order to determine and interpret where the company will be positioned with its stock, it is useful to know the industry comparison. The table from Hartmann presents a study from 1995 in which inventories are shown in relation to sales, broken down according to industries. The following percentages of inventories in relation to sales were given for the industries mentioned:
|Total manufacturing industry
More recent data was presented in the Harting publication in 2005. He states that the average inventory value is 14 percent of the turnover of German companies.
Lot size half
A calculation of the “ideal stock level” is i. d. Usually carried out according to the bottom-up approach. This is based on the question of how far the inventory can be reduced without jeopardizing the readiness for delivery. The theoretically optimal stock is determined from the safety stock plus half the optimal lot size. The bottom-up approach shows general inventory strategies.
Low value principle
The ideal stock level can also be calculated using the top-down approach.
To determine this, the IT system takes the past inventory values from a time period and selects the lowest value for each article. Then multiply the lowest value from the time period by the price / piece. You get the lowest stock value within the selected time period per article. Then the individual results for all articles are added together to produce the ideal stock based on the low value principle.
The warehouse, inventory and supply analysis
The relevant specialist literature names many theses on the formation of stocks. The following list is based on research by Hartmann, Hoppe and Schwalbach.
- Missing thematization of the inventory by the management and subordinate entrepreneurial inventory goals
- Transition from in-house production to external procurement (offshoring)
- Insufficient qualification of the dispatchers
- Incorrect lot sizes
- Incorrect safety stocks and added safety thinking in areas
- Lack of coordination between supply chains and internal and inter-company business processes
- Missing integration of the data technology
- Inadequate delivery capacity of the suppliers
- Failure to work on the inventory due to lack of knowledge of the inventory figures
- Insufficient quality of the disposition procedures
- Great depth and breadth of the range
- Decoupling of planning and control
- Fuzzy sales planning, ignorance of sales changes and poor forecast quality
- Organizational deficiencies
The following three-way relationship is established as a field of tension.
- + Sales data that are unreliable in terms of quality or time
- + Suppliers who are unreliable in terms of quality or time
- = Fuzzy decision-making basis for the dispatcher
In other words, poor input data leads to poor decisions by decision makers.
Approaches to destocking, inventory reduction and inventory reduction
Existing problems cannot be solved in isolation, but rather through the interaction of all those involved in the process . Furthermore, it can be stated that many who are responsible for the inventory in the company are not responsible for the consequences of their actions in relation to stocks or are not aware of it. The responsibility and co-responsibility for the inventory is often not attributable to a single person. An assignment of joint responsibility for the supply and the determining triggering elements is missing. On the other hand, the stocks will hide suboptimal states because weak points in the processes are concealed or not revealed. There is no need or challenge to constantly work on the best process design.
It is therefore necessary to address the stocks in order to initiate the willingness to actively participate in the causes of stocks. The order should be given by the company management, which must also support team building. The influence of a lack of supply chain management (SCM) and the resulting effects of excessive inventories on company results became clear to companies in the 1970s. Due to the high level of interest rates prevailing at the time, the companies were blocked by the debt service, based on the debt financing of the inventories. During this time, companies reacted with the first studies of the effects of the supply chain (= supplier chain) and came to the conclusion that an optimal inventory policy depends on the design of internal and inter-company business processes.
The following approaches to lowering have been shortened and essentially taken from Schwalbach's remarks.
- The product management, the construction department
Every new product development is connected with the chance to influence the inventory in the long term. In the process steps of product and presentation development, as long as the final product approval has not yet taken place, the standard or the use of existing materials can be influenced.
Article creation according to standards.
Introduction of mature articles.
Reduction of the number of articles
- Sales Sales
planning is planning that is fraught with uncertainties. Often the plan specifications and planning results do not match.
facts from market observation and demand
planning teams promoting
- Disposition & work
preparation Fields for parameter maintenance are available to the dispatchers and work planners in the available ERP system.
Selection of the disposition
procedure Qualification of the employees
Improved disposition tools
Adaptation of the forecast procedure
Change of the disposition
lot sizes Security parameters and warehouse service level
As an interface and negotiating partner, purchasing has a large number of very effective instruments at its disposal. Purchasing represents the improvement in the performance of suppliers.
Partnership cooperation with suppliers
Supply chain management / supply chain
Supplier selection, development and maintenance
- The organization
A key point in reducing the inventory is the organizational design.
Clear allocation of competencies and responsibilities.
Establishment of the working group, inventory
reduction, target agreements
- Baumann, Baumgart, Kähler, Lewerenz, Schliebner: Logistic processes - jobs in warehouse logistics ; ISBN 978-3-441-00360-1
- Kummer, Grün, Jammernegg: Fundamentals of procurement, production and logistics , Pearson, 2006, p. 216f.
- Christof Schulte: Logistics - Ways to optimize the supply chain , Vahlen, 5th edition, 2009, p. 228 f.
- Holistic warehouse planning: What do you have to consider? Retrieved April 16, 2018 .
- Horst Hartmann (1999): Inventory management and controlling , Dt. Betriebswirte Verlag GmbH; Gernsbach.
- Marc Hoppe (2005): Inventory optimization with SAP Galileo Press GmbH, Bonn.
- Lutz Schwalbach (2006): Inventory and stock reduction. Determination of potential, structured analyzes and functional solution images , BoD Verlag, Nordersted, ISBN 978-3-8334-6715-8 .
- Hartmann, Horst: Inventory management and controlling , Gernsbach: Dt. Betriebswirte Verlag GmbH 1999, p. 30.
- Horst Hartmann (1999): Inventory management and controlling , Dt. Betriebswirte Verlag, Gernsbach, p. 17.
- Detlef Harting (2005): Inventory and inventory management slim and modern , BA procurement current, issue 6, Konradin Verlag Robert Kohlhammer GmbH, Leinfelden, p. 26.
- See Rüggeberg, Christian: Supply Chain Management as a Challenge for the Future , Wiesbaden: Deutscher Universitäts-Verlag / GWV Fachverlage GmbH, 2003, p. 4 and p. 17.
- Jörg Becker, Axel Winklmann (2008): Retail Controlling . 2nd edition, Springer, Berlin, ISBN 3-540-29611-5
- Horst Tempelmeier (2006): Inventory Management in Supply Chains. 2nd Edition. Norderstedt, Books on Demand, ISBN 3-8334-5032-0 .
- Lutz Schwalbach (2006): Inventory and stock reduction. Determination of potential, structured analyzes and functional solution images. BoD Verlag: Norderstedt, ISBN 978-3-8334-6715-8
- Marc Hoppe: Inventory optimization with SAP. Bonn: Galileo Press GmbH 2005, ISBN 978-3-89842-611-4
- Gerhard Oeldorf (2004): Materials Management . Ludwigshafen, Kiel, ISBN 3-470-54141-8
- Wolfram Fischer (2004): Material flow and logistics. Springer, Berlin, ISBN 3-540-40187-3
- Wolfgang Vry (2004): Procurement and Warehousing. Ludwigshafen, Kiehl, ISBN 3-470-63127-1
- Christian Rüggeberg (2003): Supply Chain Management as a Challenge for the Future , Wiesbaden: Deutscher Universitäts-Verlag / GWV Fachverlage GmbH, p. 4 and p. 17
- Rainer Weber (2003): Contemporary materials management with storage. expert-Verlag, Renningen, ISBN 3-8169-2269-4
- Horst Hartmann (1999): inventory management and controlling , Gernsbach: Dt. Betriebswirte Verlag GmbH, ISBN 978-3-88640-083-6
- WEKA Media GmbH (since 1999): warehouse planning, organization and optimization. ISBN 3-8111-6822-3 (loose-leaf collection with CD-ROM)
- Hans Arnolds et al. / Heege, Franz / Tussing, Werner: Materials Management and Purchasing , 10th Edition, Wiesbaden: Gabler Verlag 1998, ISBN 978-3-409-35160-7