Toyota production system

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The Toyota Production System ( TPS , Japanese ト ヨ タ 生産 方式 Toyota seisan hōshiki ) is a conception to avoid any kind of waste that has developed over time at Toyota and which is constantly being developed. 'Founder' is Toyoda Sakichi , who invented the automatically stopping loom in 1902 and thus laid the basis for the Jidōka principle. His son Toyoda Kiichirō became the first chairman of Toyota Motor Corporation in 1937 and developed the "just-in-time" approach. Reasons for the emergence of the TPS were, on the one hand, the scarcity of raw materials in Japan and, on the other hand, the US policy of isolation from Japan, which, among other things, wanted to prevent Japanese competition in the automotive industry. Even after the end of World War II , Japan did not receive any economic aid from the US, so Japanese companies had to start producing automobiles with their own (modest) resources and means. As resources were scarce, what was available had to be used very sparingly, avoiding waste and using organizational means to try to optimize processes and procedures and at the same time to increase quality.

After the Second World War, the engineer and production manager Taiichi Ohno systematically developed the TPS and added many elements and methods. He wrote down his thoughts and principles in a book that appeared in Japan in 1978 and was published in English ten years later. In the preface to the English edition, T. Ohno writes: “The starting concept of the Toyota production system was, as I have emphasized several times, a thorough elimination of waste”. The starting point of the concept is then the elimination of any waste, be it in the production process or in the area of service and administration (see indirect area ). In addition, Toyota very early on evaluated the quality strategies of the American William Edwards Deming , whose ideas fell on deaf ears in his home country, and incorporated them into the production system.

The basic structure of the Toyota production system

The Toyota Motor Corporation officially described and published its production system in a "booklet" in 1992. This brochure was revised and reissued in 1998. In the preface it says:

“The TPS is a framework for conserving resources by eliminating waste. People who participate in the system learn to identify expenditures of material, effort and time that do not generate value for customers ”and further“ we have avoided a 'how-to' approach. The booklet is not a manual. Rather it is an overview of the concepts, that underlie our production system. It is a reminder that lasting gains in productivity and quality are possible whenever and wherever management and employees are united in a commitment to positive change. "

So the TPS is not a recipe book that you just have to use, how something is done and you are successful. Rather, it offers a framework and an overview of concepts that management and employees live and need to be constantly developed.

Toyota Production System

The Toyota Production System can be thought of as a house. The roof forms the top with the aim of the TPS, to achieve maximum productivity with high quality and on-time delivery. This roof is supported by two pillars, “Jidoka” and “Just-in-time”, the principles of the TPS, which are put into practice using various methods. These two pillars rest on a foundation that describes the basic procedures for implementation

  • target
    • High productivity with the highest product quality and on-time delivery
  • Jidoka principle - The Jidōka principle states that quality must arise in the process and contains the following essential elements:
    • Production stop in the event of deviations (e.g. Andon )
    • Standardized processes (see work instructions )
    • Error prevention and avoidance (e.g. Poka Yoke )
  • JIT principle - The just-in-time principle means that only what is actually needed to fulfill customer orders is produced and contains the following essential elements:
  • foundation

Explanations of some aspects of the Toyota production system

Elimination of waste

The work is made up of added value and waste. Processing times on the machine are added value. Waiting for the machine operator to finish machining or moving parts is a waste. Most factories have high stocks of materials before, during and after the manufacturing process. This allows you to compensate for missing parts on the supplier side, machine failures or poor manufacturing quality without this having any impact on the end customer. In fact, it is intentional because it is assumed that problems will arise. This condition is not perceived as wasted because it is the normal condition in most factories. So you have to avoid the problems that waste is supposed to compensate for. This assumes that the material stocks in particular are drastically reduced in the production process - which, however, has to be done in a controlled manner, because a solution must be found for all subsequent problems that prevents production downtimes. The aim is to replace waste with added value. There are seven types of waste in the Toyota production system. Waste is called " Muda " in Japanese . One way of making waste visible are the so-called Andon boards or Andon signals. The process for identifying and eliminating waste is also referred to in the literature as muda elimination.

The inventor of the Toyota Production System, Taiichi Ohno, limited himself to seven types of waste, which were supplemented by Liker, Keyte and Locher with an eighth type, underestimating or not using the skills of employees . The failure to prevent risks , machinery failures due to lack of maintenance (lack or loss Total Productive Maintenance ), lack of information (especially in ERPs ) and product designs that do not meet the customer's wishes can the waste be considered as species.

  1. Overproduction
  2. Material stocks
  3. Transports and routes
  4. cumbersome processing
  5. awkward movements
  6. Waiting times
  7. Rework

Overproduction is when more semi-finished and / or finished products were produced in a shift than were specified by the program planning for this shift. This is usually the case when the individual areas of production optimize themselves. For example, in one area there are machines that are prone to failure and that repeatedly lead to production downtimes. In order to conceal the loss of production, as much as possible is produced in the shifts in which the machine is working well, so that the subsequent area can be supplied from the buffer storage built up by the overproduction in the event of a failure in the next shift. A second reason for overproduction is too many workers on board . Bad vacation or free shift planning can mean that the foreman has more employees available in a shift than he needs for the planned program. In order to avoid problems with the works council, he does not send his colleagues home, but uses them on machines or workstations that he actually does not need during this shift. A third reason for overproduction is poor quality . If the department does not have its process under control and the scrap rates are between 2 and 20 percent, for example, an attempt will be made to produce more than is planned in the program in order to supply the following area with OK goods.

Material stocks

Material stocks should be kept as low as possible in the Toyota production system or eliminated entirely. Too much material results in costs for tied up capital, for required storage space and unnecessary transport handling. This type of waste refers to the following three types of materials:

  • Raw material in the incoming goods warehouse and in the production process
  • Semi-finished products in the production process and in semi-finished parts stores
  • Finished products in the finished parts warehouse

Synchronization of the processes

In the conventional production system, a central PPS system determines optimal batch sizes on the basis of set-up times for independently operating production areas that are organized according to the workshop principle. Each area pushes its parts into a buffer for the subsequent process ( pushing system ). With processing times of less than an hour, the production lead time is often several weeks. The Toyota production system only produces what has just been used. With quick tool changes, the production of small batches becomes economical. The lead time is almost identical to the pure processing time (cycle time). The material is constantly in flux. The processing time is reduced by over 90% compared to the pushing system. This is essentially achieved by switching from batch size production using the workshop principle to single-piece production using the one-piece flow principle . The information about what is to be produced in what quantity is passed on from the downstream area to the upstream area using a so-called Kanban card ( pulling system / pull principle ). This means that the PPS system loses its central control function. It only has a documentation function for parts or customer master data. The control function is taken over by the Kanban cards, which transport the control data decentrally. The material in the process can be gradually reduced by up to 90 percent. At the same time, the problems that arise, which are now emerging, are being resolved.

Standardization of the processes

In a well-organized factory it is clearly regulated which material is in which quantity in which area and how and with what work is carried out at the various workplaces. These rules of the game are documented and only a suggestion for improvement leads to a change in the rules of the game. Because only those who know where they stand can determine whether they are improving. Standards must be visualized for everyone in the factory. However, the publication of standards only makes sense if you can see at a glance whether they are being adhered to. Both the employees and the responsible managers must be able to recognize immediately whether the process standard is being adhered to or not. Toyota uses the principle of visualization here. Standard deviations have to catch the eye. For example, storage locations for maintenance tools are marked with their outline. If the tool is not in place, its outline makes it immediately clear which tool should be here. In order to ensure permanent compliance with the standards, they must be audited. At the audit , the managers of all hierarchical levels participate. For this, a detailed audit plan must be drawn up, from which it can be seen who is carrying out which audit and when. The auditing process is not perceived by the employees as a control, as they themselves define the reference values ​​with their standard worksheets, which is why the management's interest in adhering to the process standards is perceived as positive. Toyota builds on standards which, however, have to be constantly improved by the employees (kaizen). This enables Toyota to offer a change from monotonous, standardized processes.

Avoidance of errors, error prevention

With minimal material stocks in the process, it is essential that only good parts are passed on to the downstream area. This assumes that the product quality is constantly monitored and not just randomly. To do this, all employees in production and logistics must be trained accordingly and made aware of this problem. The method for this is called Total Quality Management (TQM). Every employee can make mistakes. The more points he has to check, the greater the likelihood that he will miss something. Therefore, the number of its test points must be reduced to a minimum, which is not a contradiction to the previous section. Automatic testing (Jidoka), the self-control of the machine, is achieved by simple sensors or guides, but the aids mentioned must not become an additional process risk. This enables the machine to recognize for itself whether the tolerances are being adhered to. If this is not the case, it stops automatically. In Japan these methods are called Poka Yoke , which means “avoiding accidental mistakes”. If an employee detects an error that cannot be rectified quickly, he pulls the Andon rope to stop the production line. This also includes the maintenance and improvement of the production facilities . The production employees are trained in maintenance and can correct faults themselves to a certain extent. Only if they fail to repair within a defined period of time does the central maintenance team take action ( autonomous maintenance ). The aim is to find the actual cause of a malfunction and then to eliminate it sustainably. The so-called “5-W method” is used, in which, by asking “why” five times, in almost all cases the actual cause of the fault can be found. The will to solve problems or malfunctions in a sustainable manner, i.e. in such a way that they never occur again, is underlined above all by the possibility that the workers can stop the assembly line using a rip cord and thus stop production. With the decentralization of maintenance, the workers are made responsible for the functionality of their machines. Since they do not automatically have a break in the event of machine malfunctions, their motivation to avoid such situations is very high. Specifically, this means that test points that are accessible without dismantling machine parts and that were often checked irregularly or not at all by the central maintenance department are now checked daily ( preventive maintenance ). This method is also known as Total Productive Maintenance (TPM). The optimal lot size determined by the PPS system is primarily dependent on the set-up time. The question arises as to whether the determined lot size is actually optimal if a competitor can convert the same system in a fifth of the time and produce a lot size that is 80% smaller than its competitor. The optimal lot size is one. In order to achieve this, you do not need a PPS system, but a setup strategy that enables small batch sizes to be produced economically. Does it really make sense to invest millions in the construction of high-bay warehouses, which in turn cause running costs, instead of training employees with a fraction of this sum and modifying the systems in a way that is easy to convert ( set-up time reduction ). The method for doing this is called SMED . SMED stands for “Single Minute Exchange of Die”, ie tool changes every minute.

Qualification and training of employees

Anyone who demands an increase in product quality must first ensure an improvement in process quality. Only when employees register that management is interested in their daily problems in the process and actively support them in solving these problems do they realize that continuous process improvement is actually wanted. Orientation towards results is demotivation. If the trainer permanently sets the bar to the high jumper at 2.30 m and does not tell him how to overcome this height, the jumper loses the fun of his sport - he resigns. Process-oriented management is supportive management. In the Toyota factories, the workers are the most important factor in the process. It was understood that investing in the qualification of employees is the decisive competitive advantage in the battle for quality and costs. Continuous process improvement means continuous qualification of employees. Toyota trains z. B. band employees in specially designated training centers before they are used in real operation. For example, painters are trained with special water training systems. This is where you practice painting a car. The water used is collected and the target quantities compared. In addition, Toyota certifies so-called master trainers, who train and advise Toyota's trainers. Training at Toyota is heavily reasoned, focused, and repetitive.

Continuous improvement process

As in politics, the fixation on the big hit also leads to a standstill in process planning. In many companies, the emphasis on innovation in planning prevents workers from actively participating in the design of their workplaces. The risky and expensive automation of complex activities takes away any space for inexpensive organizational improvement of processes. In addition, a bureaucratic suggestion system often prevents the number of suggestions for improvement from increasing significantly. In German industry, 100 employees make around 60 suggestions per year. In the Toyota factories, however, a single employee makes an average of 62 suggestions for improvement per year. If you give one (every) employee the opportunity to improve the conditions at their own workplace, a considerable creative potential is released. At his workplace he is the expert - not the engineer who planned this workplace months or years ago. The employee struggles with daily problems and often asks himself why this way and not another? Only by helping to shape the workplace does it become “his” workplace. The 5-S method is used for this purpose, for example . The aim is to use induction programs, group discussions and Kaizen workshops to motivate employees to make suggestions for improving their workplaces or processes. Kaizen is what the Japanese call this continuous improvement process . Toyota has a detailed bonus system for this, in which the quick reward of suggestions for improvement has top priority. The Toyota bonus system differs significantly from the company suggestion scheme in Germany.

Comparison with other systems and reception in the west

In order for the Toyota production system to work, a considerable degree of discipline on the part of employees and a high level of leadership quality and determination to lead on the part of superiors are required. In the Toyota production system, the focus is on people and not on robots. Production has to be efficient, but the workers who make the products deserve respect and have the right to a meaningful task. Unlike in many other factories, the workers are not just the ones who screw in the screws ; they are asked to complain about anything they do not like about their workflow and to make suggestions on how the processes can be improved. This means that the worker has to think about what he is doing in his work.

This is a major difference to Henry Ford's production philosophy . The workload there was so minimal that the worker no longer had to think. There was only one motto here and that was “Move the sheet!” Toyota, on the other hand, gave its workers the opportunity to stop the assembly line if there was a problem and to solve the problem on the spot. This gives the worker on the assembly line a considerable amount of responsibility, which was not there before.

The Toyota Production System (TPS) is a global benchmark for highly efficient production in a wide variety of industries. "Toyota is synonymous with consistency," said Porsche ex-boss Dr. Wendelin Wiedeking . He is an avowed admirer and imitator of the Toyota production system. In the eyes of many, Toyota stands for cost and quality leadership and constant improvement.

Although the TPS has been described in detail in Western literature since the 1980s, it is estimated that no more than 10% of companies in Germany are organized according to this principle today. In the automobile industry, however, almost all automobile manufacturers and many suppliers have now developed and introduced their own production systems - mostly based on the Toyota model. The first German manufacturer was Adam Opel AG in 1992 , followed by Mercedes-Benz , MAN , Audi and Volkswagen . Large suppliers, such as Robert Bosch GmbH , have also successfully introduced their own production systems in their companies.

The Toyota production system not only works in large multinational companies, but can also be successfully implemented in medium-sized companies in a somewhat simplified form.

Evaluation of the method

The TPS method was examined several times, with the results differing significantly from each other. Some authors see the TPS as a method, others question this status.

"I believe that the approaches travel easily to other countries ... Japanese production and quality management works in non-Japanese settings."

"I think the approach can easily be transferred to other countries ... Japanese production philosophy can easily be transferred to non-Japanese environments."

- Richard J. Schonberger

"The author firmly believes the Toyota production system can play a great role in the task for improving the constitutions of American and European companies ..."

"The author firmly believes that the Toyota Production System can play an essential role in improving the health of American and European companies ..."

- Yasuhio moons

" Hall , in his widely read JIT text, never even questioned whether JIT is a system, and proceeded to give detailed information on implementing it through such steps as flow balancing, quality improvements, and setup reduction."

"Hall, in his widely used JIT text, did not even examine whether the JIT was a system and went on to describe detailed implementation methods such as flow balancing, quality improvements and set-up time reductions."

- Wallace J. Hopp , Mark L. Spearman

Robert H. Hayes could not find any particularly pronounced use of modern production technologies, quality circles or uniform remuneration systems. In my own words:

"... no exotic, strikingly different Japanese way of doing things."

"... no exotic, obviously different Japanese way of approaching the matter."

- Robert H. Hayes

“The modern Japanese factory is not, as many Americans believe, a prototype of the factory of the future. If it were, it might be, curiously, far less of a threat. We in the United States, with our technical ability and resources, ought then to be able to duplicate it. Instead, it is something much more difficult for us to copy; it is the factory of today running as it should. "

“The modern Japanese factory is not - as many Americans believe - the prototype of the factory of the future. Oddly enough, if that were true, it might pose a much smaller threat. We in the United States, with our technical skills and resources, should then be able to do it. Instead, it's something that is much more difficult to copy: It's today's factory that runs as it should! "

- Robert H. Hayes

Many of these interpretations are attributed to the fact that the respective authors did not have complete information about the system at the time their studies were carried out in the 1980s. Ohno even admitted that confusing terminology was deliberately used to make it difficult to understand (Myers (1990) cited in Hopp, 1999). It has meanwhile been shown that the TPS can also be adapted to the mentality of workers and corporate cultures in countries outside of Japan or, conversely, the workers and cultures to the TPS.

It turns out, however, that the corporate culture ( the way we do things around here ) and the sometimes considerable changes play an essential role in the introduction. This also explains why it took Toyota 50 years to get where it is today, and only about 20 percent of companies in Japan use the TPS. Obviously, it is difficult to achieve such a fundamental change in Japan as well.

literature

Magazines

  • Toyota's secret. In: Wirtschaftswoche. 20/2004.
  • Supply chain: the perfect logistics system. In: Harvard Business Manager. 1/2005.
  • Management a la Toyota. In: Harvard Business Manager. 8/2004.
  • Learning to lead at Toyota. In: Harvard Business Review. May 2004.
  • Triple A supply chain. In: Harvard Business Review. October 2004.
  • The lean service machine. In: Harvard Business Review. October 2003.
  • Decoding the DNA of the Toyota Production System. In: Harvard Business Review. September / October 1999.
  • Volker Elis: From America to Japan - and back. The historical roots and transformations of Toyotism. In: Zeithistorische Forschungen / Studies in Contemporary History. 6, 2009, pp. 255-275.

Web links

Individual evidence

  1. ^ Taiichi Ohno: Toyota Production System - Beyond Large-Scale Production. Productivity Press, Cambridge Massachusetts 1988.
  2. ^ Toyota Motor Corporation: The Toyota Production System - Leaner manufacturing for a greener planet. TMC, Public Affairs Division, Tokyo 1998.
  3. ↑ ibid, p. 2.
  4. ^ W. Herlyn: PPS in automobile construction. Munich 2012, p. 49 ff.
  5. ↑ JK Liker: The Toyota Way. Mc Graw Hill, 2005, p. 29.
  6. ^ JP Womack, DT Jones: Lean Thinking. Mc Graw Hill, 2003, p. 15 i. V. m, p. 354.
  7. ↑ AP: Automotive Lean Production Study ( Memento from January 25, 2008 in the Internet Archive ) (July 24, 2006)
  8. ^ W. Herlyn: PPS in automobile construction. P. 46 ff.
  9. ↑ A simplified Toyota Production System for medium-sized companies (PDF; 239 kB)
  10. ^ Richard J. Schonberger : Japanese Manufacturing Techniques: Nine Hidden Lessons in Simplicity. Free Press, New York 1982.
  11. ^ Moons : Toyota Production System: Practical Approach to Production Management. 1983.
  12. ^ A b Robert W. Hall : Driving the Productivity Machine: Production Planning and Control in Japan. American Production and Inventory Control Society, Falls Church, VA 1981.
  13. ^ Wallace J. Hopp , Mark L. Spearman : Factory Physics: foundations of manufacturing management. 2nd Edition. McGraw-Hill Higher Education, 2000, ISBN 0-256-24795-1 (www.mhhe.com)
  14. ^ A b c Robert H. Hayes: Why Japanese Factories Work. In: Harvard Business Review. July-August 1981, pp. 57-66.