Inventory management

from Wikipedia, the free encyclopedia

The inventory management deals in company with the reduction of inventory levels while maintaining or enhancing the delivery service and the resulting customer satisfaction .

General

On the basis of product-specific planning strategies - classification of the products according to the ABC / XYZ analysis - inventory management takes place in three process steps:

Demand planning

Demand planning is concerned with determining future demand. In principle, a distinction can be made between two methods - program-related and consumption-related requirements planning. While the program-related requirements planning is based on specific customer orders or a production program , the consumption- related requirements planning is carried out using forecasting methods against the background of periodized consumption in the past.

Basically, a distinction must be made between scheduling and quantity planning . ERP systems first determine the requirements date based on a forward or backward date calculation. If the date is deemed to have been determined, the required quantity is calculated. The arithmetic required quantity is adjusted using lot size calculation methods (static, periodic or optimizing methods). In addition, the lot size can be changed via so-called rounding values ​​(full pallet, unit ...) or minimum order values ​​or minimum order quantities for the supplier.

Inventory planning

The necessary stocks are determined in the inventory planning. The focus of the company is on determining the optimal safety stock and the order trigger stock against the background of stochastic or deterministic demand and supply processes. Further stocks are maximum or maximum stocks, which may not be exceeded due to warehouse restrictions, as well as reporting stocks as an additional control instrument, in which one or more employees are automatically informed when a certain number of items in the warehouse is not reached.

Procurement planning

Finally, the order policy is determined in the procurement planning - depending on the order policy, the time of order is selected according to the characteristics of the article, and the optimal order quantity is also determined for the specific article with the help of suitable heuristic and / or optimizing processes.

With the optimizing lot-sizing method, required quantities of several periods are combined into one lot-size, whereby an optimum cost is determined between lot-size-fixed costs and storage costs. The different optimization methods only differ in the type of cost minimum. There are the following optimizing methods of lot size calculation:

The optimization of the inventory management enables an overall improvement of the cost situation in the company and leads to an increased logistical efficiency.

Importance of inventory management for companies

Inventory management is of considerable importance in organizations in all industries, after all , companies tie up their liquidity at the inventory interest rate through inventory. A systematic management of the inventory thus lowers the capital requirements and above all the inventory risk of the organizations. Since inventories as essential balance position the current assets are to be assigned, it follows that a reduction in inventory on the reduction of the position "inventories" employed total capital reduced. With the same company result, all other things being equal, the reduction in capital commitment means an increase in the return on equity . However, it is just as important to have the goods you need and always have enough in stock to avoid delivery bottlenecks.

Target system

The target system for the economic assessment of the inventory management or the disposition is to be described by three measurable dimensions in main features - delivery service , capital commitment and capital commitment costs.

The target dimension "delivery service" includes the quantity-, time- and quality-oriented improvement of the ability to deliver as well as the readiness to deliver. When assessing the delivery service, the ability to deliver, the readiness to deliver, the quantities and adherence to deadlines as well as the number of stock-outs are taken into account. The "capital commitment" includes the minimization of inventories starting with the raw materials, auxiliary materials and supplies, spare parts, semi-finished products up to the finished products. The third target dimension "inventory costs" also considers the continuously occurring costs in the area of ​​inventory management.

The target system can be used for a measurable, economic assessment of inventory management. On the one hand, customer satisfaction is taken into account indirectly through the delivery service and, on the other hand, the costs. Therefore, the basic task of inventory management is to find the best possible balance in the conflict between the partly opposing target values ​​of the disposition.

Due to the different complexity of products and different manufacturing methods, absolute numbers are not always comparable and can only rarely be used within a company to measure the performance of the disposition in reducing inventory. Whether measures with the aim of inventory reduction were successful can be measured realistically in two ways:
- If there are requirements, the scope of the inventory can be compared to the requirements. If the range decreases, the inventory reduction measures have been successful. A breakdown into A, B and C parts and the determination of the average range within these parts categories is also useful.
- Alternatively, the stocks can be put in relation to the sales. From the point of view of the efficiency of measures for inventory-reducing measures, this makes more sense than the consideration of the absolute inventory in the case of fluctuating sales figures. The ratio of products sold to manufacturing (ies) costs in relation to stocks is even more precise.
Example: Inventory / sales at manufacturing costs = inventory
quota using manufacturing costs instead of sales has the advantage that rising or falling profit margins do not distort the picture.

Individual evidence

  1. ^ Wallace J. Hopp, Mark L. Spearman: Factory Physics: foundations of manufacturing management. 2nd Edition. McGraw-Hill Higher Education, Boston 2000, ISBN 0-256-24795-1 .

Bibliography

  • Knut Alicke: Planning and operation of logistics networks: cross-company supply chain management. 2nd Edition. Springer-Verlag, Berlin / Heidelberg 2005, ISBN 3-540-44370-3 .
  • H. Baumgarten, J. Becker, H.-P. Wiendahl, J. Zentes: Logistics Management, Strategies - Concepts - Practical Examples . Springer-Verlag, Berlin / Heidelberg 2004.
  • Timm Gudehus: Logistics - Basics, Strategies, Applications . Springer-Verlag, Berlin / Heidelberg / New York 1999, ISBN 3-540-40586-0 .
  • Horst Hartmann: Materials management - organization, planning, implementation, control. 8th edition. Deutscher Betriebswirte-Verlag, Gernsbach 2002, ISBN 3-8006-1755-2 .
  • Marc Hoppe: Inventory optimization with SAP . Galileo Press, Bonn 2005, ISBN 3-89842-611-4 .
  • Holger Luczak, Volker Stich: Industrial Logistics. 8th edition. Verlag der Augustinus Buchhandlung, Aachen 2004.
  • Jan Christoph Meyer: Modern disposition procedures. In: Modern Disposition. Management Circle, Eschborn 2006.
  • Paul Schönsleben: Integral logistics management. Planning and control of comprehensive business processes . Springer Verlag, Berlin / Heidelberg / New York 2000, ISBN 3-540-21177-2 .
  • Günther Schuh (Ed.): Production planning and control - basics, design and concepts. 3. Edition. Springer-Verlag, Berlin / Heidelberg 2006, ISBN 3-540-40306-X .
  • Horst Tempelmeier: Inventory management in supply chains. 2nd Edition. Books on Demand, Norderstedt 2007, ISBN 978-3-8334-5032-7 .
  • H. Tempelmeier: Material logistics. 7th edition. Springer-Verlag, Berlin / Heidelberg / New York 2008, ISBN 978-3-540-28425-3 .
  • Kirk D. Zylstra: Lean Distribution - Applying Lean Manufacturing to Distribution, Logistics, and Supply Chain Management . John Wiley & Sons, 2006, ISBN 0-471-74075-6 .
  • Hans Arnolds, Franz Heege, Werner Tussing: Materials management and purchasing. 10th edition. Gabler Verlag, Wiesbaden 1998, ISBN 3-409-35160-4 .
  • Lutz Schwalbach: Inventory and stock reduction. Determination of potential, structured analyzes and functional solution images. BoD Verlag, Norderstedt 2006, ISBN 978-3-8334-6715-8 .