Toyota production system (TPS) is of Toyota in one period of over 50 years developed production procedure. It connects the productivity of the mass production with the quality of the Werkstattfertigung. For Japan there were after the end 2. World war an economical assistance of the USA and so the Japanese companies with modest means did not have to enter into the world market. Money for new machines was missing, therefore one concentrated on the improvement of the organizational operational sequence.

Considerably the TPS was developed by engineers Taiichi Ohno and Shigeo Shingo. A goal is production in the customer clock with if possible small Verschwendung of resources of any kind in the production process. The information, which is to be produced in which quantity, passed on by the stored range by means of Kanbankarten to the pre-aged range. Thus only one produces, which was used straight.

The result are minimum inventories in the process. Such a process can function only reliably, if the qualification of the coworkers, who are sufficient for availability of the machines and the intermediate products very high standards produced during the process. Already very early Toyota converted the quality strategies of the American Edward Deming, whose ideas are discovered in its homeland deaf ears, with large success.

The elements of the Toyota production system

• A goal: Production in the customer clock
• Strategy: Elimination of the Verschwendung in the production process
• Methods:
  • Synchronization of the processes
  • Standardisation of the processes
  • Avoidance of errors
  • Improvement of the production plants
  • Qualification and training of the coworkers
• Basis: Continuous far improvement of the processes

Production in the customer clock

If the final assembly of the supplier manufactures faster than the customer, then existence of finished units develop themselves with the supplier. If the final assembly of the supplier produces more slowly than the customer, then sometime its finished unit camp is empty and it is not supplyable any longer.

Only if the final assembly of the supplier in the same clock produces as the customer, a structure at finished unit existence, or a delivery outline can be avoided. Which applies to the synchronization of the supplier with the external customer, applies also to the synchronization of internal customers and internal suppliers.

If the final assembly in the same clock produces as the external customer and on the basis of the final assembly all pre-aged ranges only after-produces, which was used straight, one speaks Just in Time, or Just in Sequence of a pulling system, which produces synchronously to the customer clock, thus.

Since customer orderings vary often strongly, one tries to smooth production in the Toyota production system. For production it is to be produced on the simplest each day of the same part the same quantity. The adjustment of production to those of the external customer does not mean that one submits to on and starting from the daily order fluctuations.

It is sufficient perfectly, if one drives for example one week long a constant production program. One specifies once per week, which numbers of items are to be manufactured in the subsequent week by each part per day. This week program levels the order fluctuations of the customers and provides for a calm and continuous production under the week.

Elimination of the Verschwendung in the production process

Work sits down together from creation of value and Verschwendung. Operating time on the machine is creation of value. Waiting the machine operator for the end of the phase of operation, or transporting parts is Verschwendung. It is quite possible that 4 coworkers, whose task is it to install parts in a layer put 24 km back, because the manufacturing layout is not optimal.

In most factories it gives high inventories, in and after the manufacturing process. Thus one can compensate absence hurry on the Zulieferseite, machine failures or bad without this has effects on the final customers. It is even so intended, because one assumes it comes to problems. This condition is not felt as Verschwendung, because it is in most factories the normal condition.

One must avoid thus the problems, which are compensated by Verschwendung. This presupposes that in particular the inventories in the manufacturing process are drastically reduced. This must take place controlled, because for all problems arising then a solution must be found, the losses of production prevented.

A goal with has it replacing Verschwendung by creation of value. With respect to the Toyota production system one differentiates 7 kinds of kindkind. The Verschwendung is called in the Japanese Muda. A possibility of making Verschwendung visible are the so-called and on boards or and on signals. The procedure for the recognition and removal of the Verschwendung is called in the literature also Muda Elimination.

Synchronization of the processes

In the conventional production system a central PPS system on the basis of preparation times determines optimal lot sizes for independently acting production areas, which are organized according to the workshop principle. Each range pushes its parts into a buffer for the following process (pushing system). At operating time of less than one hour, the production turn-around time often is at several weeks.

In the Toyota production system only one produces, which was used straight. With fast tool changes the production of small lot sizes becomes economical. The turn-around time is nearly identical with the pure operating time. The material is permanent in the river. The turn-around time reduces in relation to the pushing system over over 90%. This is essentially reached by the conversion of the lot size manufacturing in the workshop principle to the unique piece manufacturing in the flow principle (One Piece flow).

The information, which is to be produced in which quantity, of the stored range by means of a so-called Kanbankarte to the pre-aged range passed on (pulling system). Thus the PPS system loses its central control function. It has only documentation function for data on regular customers or dividing. The Kanbankarten, which transports the control data decentralized, takes over the control function.

The material during the process can be reduced gradually over up to 90%. Parallel to it the arising problems, which step now to day, are solved.

Standardisation of the processes

In a well organized factory is clearly regulated, which material in which quantity stands on which surface and how and with which on the different jobs is worked. These rules are documented and only one improvement suggestion lead to a change of the rules. Because only who white where it stands, can determine whether he improves.

Standards must be visibly visualized for everyone in the factory. The publication of standards is however meaningful only if one can recognize on a view whether they are kept. Both the coworkers as well as the responsible persons of high-level personnel must be able to recognize immediately whether the process standard is kept or not.

In order to guarantee the durable adherence to the standards, these must be audited. In auditing the high-level personnel of all hierarchy levels takes part. But a detailed auditing plan is to be provided, is shown by which, who when accomplishes which audit. The auditing procedure is not felt of the coworkers as control, since they define the appoximate values with their standard papers themselves, why the interest of the management in the adherence to the process standards is felt rather as positive.

Avoidance of errors

With minimum inventories during the process it is indispensable that only property goods are passed on to the stored range. This presupposes that the product quality is not only supervised constantly by samples. In addition all coworkers must be sensitized by production and logistics accordingly trained and for this problem. The method for this is called total quality management (TQM).

Each coworker can make errors. The more points it to examine, is the larger the probability must that it surveys something. Therefore the number of its checkpoints must be reduced to a minimum, no contradiction is preceded which to the section.

Automatic examining, the self-check of the machine, reached by simple sensors or guidance, but the aids mentioned may not become an additional process risk. Thus the machine is put into the position to even recognize whether the tolerances are kept. If this is not the case, she continues automatically. In Japan one calls these methods Poka Yoke, which means as much, like "“avoidance of coincidental errors"”.

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