Lean production as a translation of English " lean production " and " lean manufacturing " referred originally from Womack / Jones / Roos in the MIT study (1985 to 1991) among Japanese automakers vorgefundene, systematic organization of production , which in the United States and Europe to this time prevailing and from them so-called buffered production (" Buffered Production ") was opposed.
Shah / Ward (2007) understand lean production as an "integrated socio-technical system, the core objective of which is the elimination of waste by reducing or minimizing fluctuations on the supplier, customer and internal side" regardless of this definition related to the situation at the time . On the contrary, Christoph Deutschmann sees the function of lean production in the abolition of the principle of “shielding production systems from the contingencies of the market”. in other words, in the possibility of faster reactions to market changes, with the task of adapting and rationalizing production using standardized methods being decentralized and shifted further down the hierarchy. For the application of such lean production methods, the term “ holistic production systems” has become established in German-speaking countries .
Representatives of the future project Industry 4.0 explain that this approach supports lean production, as the transparency of networked systems supports the continuous improvement process. Others counter that Industry 4.0 as an automation concept entails the opposite of a leaner production, because it is not based on the economic imperative, according to which expenditure and benefits should be in an economic relationship, but the technological imperative, according to technology which is available should also be used (no matter what the cost).
Part of lean management
Womack / Jones / Roos already described more than a pure production system . Thus, the term was soon concepts such as lean management ( " lean administration ") or lean maintenance ( " Lean Maintenance ") framed and on companies whose production is characterized by unique objects or small batch production, expanded and eventually lean management ( " Lean Management ") further developed. This is now understood to be a corporate philosophy of omitting (down to the smallest detail) all superfluous operations in production and administration through a more intelligent organization. It is based on innovative changes in the value chain and the actors accompanying it (such as customers , suppliers , trade unions , investors , municipalities ) and on a partnership between leading and executing actors ( employee management ).
Design principles of lean production systems
In its early days, lean production was often associated with rationalization measures. This misinterpretation resulted in a loss of trust within the workforce. It quickly became clear that the methods of lean production systems only lead to sustained success if the overall system is consistently focused on customer benefit. This approach ultimately also helped the Toyota Production System (TPS) achieve a breakthrough. For the holistic orientation of a production system, the term holistic production systems (GPS) has established itself in German-speaking countries . Holistic production systems provide a company-specific alignment of the production system using the methods of lean production. A distinction is made between eight design principles of holistic production systems ( Dombrowski , Chapter 2).
Avoidance of Waste
Avoiding waste is the fundamental goal of holistic production systems. This design principle aims to eliminate all non-value-adding activities within the production system. Activities that add value to the customer are called value-adding activities. Activities that do not add value are therefore to be regarded as waste. However, it must be taken into account that there are non-value-adding activities that are necessary for the product creation process, such as B. Research and development activities, production planning or other indirect areas.
For an overview of the types of waste ( Muda ), please refer to the following section.
Avoiding or minimizing waste through lean production leads to more efficient processes and thus also to fewer resources. The use of resources combines lean production with green management and supports the sustainable development of a company. A particularly lean company is also more resource-efficient and therefore green. Lean & Green Management represents a further development of the lean production and lean management approaches and aims to continuously improve the environmental balance sheet of companies in addition to increasing competitiveness . With Lean & Green concepts, optimizing processes and minimizing waste is not only a means of increasing the company's success, but also improves the company's environmental and social impact, which in turn brings benefits to society as a whole.
Continuous improvement process
The goal of a holistic production system is to strive for perfection. This requires a continuous drive to improve existing processes and systems ( continuous improvement process ). A prerequisite for this is the involvement of all employees in the improvement process. The staff of a company should always question all methods, processes and tools and improve them if necessary. In this context, the design of an internal idea management system is useful. With every improvement, errors, problems and wastes are discovered and eliminated.
Standardization deals with the definition of action steps in relation to repetitive processes, workflows, production steps as well as planning and design tasks. The aim of standardization is to eliminate activities that do not add value and to increase process stability.
Zero defect principle
The zero-error principle pursues the goal of avoiding the passing on of errors to subsequent work steps and thus increasing the product and process quality. This design principle also contains methods for avoiding errors within a process chain and is closely linked to the methods of Total Quality Management (TQM).
The flow principle aims to achieve a fast, continuous and low-turbulence flow of materials and information in order to achieve the shortest possible lead time over the entire value chain. Products should be transported from one process step to the next without intermediate storage, without restricting the company's flexibility.
The pull principle is to pull a customer order through the production process . The counterpart is the push principle, in which production orders are pushed through the value chain on the basis of forecast customer requirements. The pull principle is based on specific customer orders and aims to minimize control effort and inventory. This design principle is often used in production in connection with methods such as Just in Time (JIT), Just in Sequence (JIS), Kanban or Milkrun .
Employee orientation and goal-oriented leadership
Employee orientation and goal-oriented management in production companies must meet the requirements of holistic production systems. The Tayloristic division of production work into head and manual work is no longer up to date. In the context of holistic production systems, the employees of a company are seen as crucial resources for innovative concepts and continuous process improvements. The error-free and waste-free way of working of managers and employees must be ensured in order to achieve the desired result. The aspect of employee management concerns the daily interaction between employees and managers, whereby both parties benefit from goal-oriented management with clearly defined guidelines and a consistent target structure within the GPS.
The main goal of visual management is the graphic representation of information about processes and work flows. This is intended to create a high level of transparency about goals, processes and services within a GPS. In this way, it is possible for employees and managers to receive information on production-relevant key figures in a short time. The transparency and the resulting involvement of the employees should lead to a stronger identification with the workplace and the task. In addition, problems and deviations from targets are immediately apparent so that appropriate measures can be taken immediately. This also helps to reduce waste and supports the continuous improvement process.
Finding and eliminating waste is a central part of the Lean concept. In the Japanese approach, the consistency in the implementation of waste minimization is particularly evident. Waste is everything that does not directly add value.
All expenses for which the customer would not be willing to pay are considered waste.
This results in a concentration on the value creation process and a classification into the core process (creates direct customer benefit), support process (is essential for handling the core processes), blind process (causes effort without contributing to customer benefit) and defective process (destroys customer benefit already created) . The latter two are to be avoided, the first two are to be organized as well as possible.
Eight forms of waste are often identified and classified for in-kind production:
- Overproduction : All products, semi-finished products and services that are created without being requested by the customer. Most of the following wastes are caused by overproduction, among others.
- Stocks: Stocks as production buffers hide weak points, as overproduction they tie up capital, space and generate useless handling effort. In the end, stocks often have to be written off and also simulate a service in accounting that does not affect income.
- Transport: Material transport does not bring the product any direct customer benefit. Storage processes are mostly to be viewed as blind processes.
- Waiting time: Stagnant or idle processes, missing material, disrupted or unsuitable operating resources, etc. tie up resources that can no longer be used to add value during these times.
- Elaborate processes: If production is insufficiently included in the development process, unsuitable operating resources and unsuitable systems, etc., processes are usually difficult to control. This causes errors, generally reduces flexibility, leads to incorrect processes and unproductive waiting times.
- Long distances: A fluid production process can be disturbed by long distances.
- Defects: Defective products mean effort to correct (blind processes) or performance that is lost in rejects (faulty process). Furthermore, the disturbed process must start again (blind process).
- Unused potential: All the knowledge and skills of the employees in the process that is not used to improve the overall process is considered waste (in some places also referred to as a "luxury of a special kind").
It is important to differentiate between avoidable and unavoidable waste. For example, many documentation processes are often unavoidable (which must be carefully checked), but from an orthodox point of view they are still “waste”. Avoidable waste must be consistently eliminated.
The Kaizen with its techniques 5S , SMED , Jidoka (also called Autonomation ), Poka-Yoke , Heikinka (also called Leveling ), Heijunka (also called Smoothed Production ) etc., like the TQM, has emerged as an independent concept from the Lean Production System developed out.
A key message in lean production is to continuously process the material from the start of a production process to the completion of a product. This means that there are no more buffer quantities (see waste type “overproduction”) between process steps. The immediate consequence of this is a much shorter lead time with beneficial consequences in terms of flexibility, delivery reliability and capital commitment. In addition, there is an increase in area productivity and less waste due to material transport, stocks, etc. The ideal state of continuous flow production is the one-piece flow ( employee-related work flow ).
- U. Dombrowski , T. Mielke (Hrsg.): Holistic production systems: current status and future developments (VDI book). Springer Vieweg, Heidelberg 2015.
- Jan Alonso-Michel: Leadership as a Sustainable Success Factor of Lean Manufacturing . (PDF; 860 kB). MBA thesis. International Lean Manufacturing Consulting, April 2008. (English)
- Georg Ullmann: Collection with 73 lean methods. ( Memento from February 18, 2015 in the Internet Archive ) (PDF; 3.5 MB). Objectives, advantages and disadvantages, notes on implementation, examples and further literature, IPH - Institute for Integrated Production Hannover gGmbH , November 2009.
J. Womack, D. Jones, D. Roos: The Machine that Changed the World: The Story of Lean Production. Harper Collins, New York 1990, ISBN 0-06-097417-6 ;
German translation: The second revolution in the auto industry. 4th edition. Campus, Frankfurt am Main 1992, ISBN 3-453-11750-6 .
The term was coined in 1988 by John Krafcik in the report Triumph of the Lean Production , which was part of the study and was published in Sloan Management Review .
- R. Shah, PT Ward: Defining and developing measures of lean production. In: Journal of Operations Management. 25, 2007, pp. 785-805. (In the English original: "Lean production is an integrated socio-technical system whose main objective is to eliminate waste by concurrently reducing or minimizing supplier, customer, and internal variability.")
- Christoph Deutschmann: Post-industrial industrial sociology. Weinheim and Munich 2002, p. 25.
- Editorial office IG Metall: IG Metall - Holistic Production Systems: What is it? In: www.igmetall.de. Retrieved January 17, 2017 .
- U. Dombrowski , T. Richter: Holistic production systems and Industry 4.0. In: ZWF. 111, 12, 2016, pp. 771-774.
- Volker Ahrens: The future importance of REFA - methodology in the context of Industry 4.0 . In: NORDAKADEMIE working papers . No. 2018-01 . NORDAKADEMIE, June 2018, ISSN 1860-0360 , p. 4 ( nordakademie.de [PDF]).
- G. Ullmann, L. Overmeyer: Expert system for the introduction of lean production in tool making . In: German Society for Quality e. V. (Ed.): FQS-DGQ. Volume 88-07, 1st edition. Frankfurt am Main 2010, ISBN 978-3-940991-08-9 .
- W. Pfeiffer, E. Weiss: Lean Management: Basics of the management and organization of learning companies. 2nd Edition. E. Schmidt, Berlin 1994, ISBN 3-503-03678-4 . Here the term is expanded to include lean management, which then includes, for example, “ simultaneous engineering ” and a bridge is built to the much-misused term of the paradigm shift in the organization
- U. Dombrowski , T. Mielke (ed.): Holistic production systems: Current status and future developments (VDI book). Springer Vieweg, Heidelberg 2015, ISBN 978-3-662-46163-1 .
- VDI 2870-1: Holistic Production Systems - Basics, Introduction and Evaluation . VDI - Association of German Engineers V. (ed.). Beuth Verlag, Berlin 2012.