Just in Time Method

We explain what the method is just in time or Toyota method and what its principles are. In addition, we tell you how it was invented.

In an automotive factory the just in time method is used.In an automotive factory the just in time method is used.
With the method just in time Each element arrives when it is needed and in the right quantity.

What is the method just in time?

The method just in time (abbreviated JIT) or Toyota method is a method of organizing industrial production that Lowers production costs by eliminating the need for storage and inventory of raw materials, parts and even final products. To achieve this, it is proposed that these elements arrive at their destination at the precise time they are needed and in the exact quantity in which they are needed.

The name of this method comes from this fundamental idea: the phrase “just in time” means in English “just in time”, that is, The elements arrive shortly before being needed, without delays or advances, so as not to interrupt the production circuitbut neither require additional storage expenses.

The method just in time It is a minimalist method, which tends to reduce not only storage costs (stocks), but also the waste of resources, manufacturing and delivery times, for which it requires, however, zero tolerance for errors and inputs free of defects. This production methodology has been successful mainly in the automotive industry, especially in companies capable of managing numerous suppliers for a much smaller number of factories equipped with no more than two dozen assembly lines.

See also: Kaizen Method

Origin of the method just in time

The method just in time It is of Japanese origin. It arose in the Toyota automobile plant between 1938 and 1939, and was exported to the West much later.. It is attributed to the Japanese entrepreneur and industrialist Kiichiro Toyoda (1894-1952), son of Sakichi Toyoda, founder of Toyota Loom Works, an automotive company that later became Toyota Motor Corporation.

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According to Jiro Iwaoka, head of Toyota’s engine division at the time, Kiichiro himself expressed the need to “guarantee that there is no shortage or excess, that is, to guarantee that there is no more work than possible nor more time available than necessary to carry out planned production. Without lack or excess: that the pieces do not “wait”, but rather flow through the process”. This, according to the entrepreneur, was productive efficiency.

Principles of the method just in time

An assembly line organizes all the inputs around it.An assembly line organizes all the inputs around it.
The method just in time requires multipurpose tools and the versatility of workers.

The fundamentals of the method just in time They can be summarized as follows:

  • Minimization of stocks. The characteristic principle of this production method is that it does not require large storage quotas: neither raw materials, nor inputs or parts, since all these elements must arrive at their destination just before being used (“just in time”). , without having to store them for a long time.
  • Minimization of production and delivery times. Manufacturing times are also significantly shortened in this model, through the simplification or elimination of material and machinery movements, the reduction of waiting times, the reduction of processing batches and the increase in production efficiency. machinery.
  • Flexibility of productive resources. This means the use of multipurpose tools and the preparation of versatile workers, capable of operating different machinery, arranged in a “U” shape around each workplace. Likewise, machinery interruption systems are used once their work is completed, and labor rotation plans are used in each plant.
  • Cellular distribution of productive plants. Factories began to be organized on the basis of “cells”, that is, groups of machines of different types capable of producing similar parts, and arranged in such a way that different products can be manufactured simultaneously.
  • System pull and not push. A productive start-up system or pull (in English “pull” or “throw”) is one in which each productive stage “asks” from the previous ones for the necessary material to continue their work, so that the workers can go back to the previous instance and move the necessary materials to continue the circuit. This is the opposite perspective to push systems or “push”, in which each productive instance finishes its task and then takes the materials to the next stage.
  • 5S methodology. To start the method just in time It is necessary to implement “5S” in the workplace, that is, five key concepts whose Japanese names begin with S: Seiri (“Sort out”), Seiton (“Order”), Seiso (“Cleaning”), Seiketsu (“Standardize”) and Shitsuke (“Discipline”).
  • Reduction in errors and technical stops. To ensure system flow just in time, there can be no errors that interrupt the chain or delay the flow of materials necessary to produce, nor can there be breakdowns and downtime due to machines or tool changes. The adaptation of the machines must be quick and effective, according to the SMED system (English single-minute exchange of die).
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Advantages and disadvantages of the method just in time

Like all production methods, the just in time It has advantages and disadvantages, such as:

Advantages of the method just in time Disadvantages of the method just in time
Production costs are reduced by reducing the stocks and the margin of waste is minimized. It requires great coordination between suppliers, clients and production instances, at the risk of causing delays and shortages. stocks.
Prevents the loss of productive inputs due to the passage of time (deterioration). When making small purchases from suppliers, material prices tend to be higher.
It simplifies the supply chain, which gives the system great adaptability. It must be implemented throughout the company, without the possibility of partial adaptations.
Facilitates reverse logistics operations, such as returns. It requires very reliable and permanent suppliers, as the cost of changing suppliers increases.

Examples of application of the method just in time

The system just in time It is successfully used in the automotive plants of the Japanese company Toyota, and this company constitutes the best and main example of the application of this production methodology. Other possible examples are:

  • fast food companies who request new stocks of materials in short periods (daily or weekly), and consume them throughout the day, without giving them a chance to deteriorate.
  • The American motorcycle company Harley Davidsonfamous for its wasteful margins and inefficiency, adopted the method just in time to significantly reduce your delivery times and inventory levels.
  • Computer companies such as the American multinational Dell They eliminated the need to store their supplies, undertaking a successful dynamic of continuous requests from local suppliers.
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The kanban method

The kanban method, whose name in Japanese means “sign” or “poster,” is an information management system that seeks to harmoniously control the production system, using for this cards that adhere to the material containers acting as witnesses of the production process. Thus, when the material is used, the card comes off and indicates that it will need to be replaced immediately. In this way the kanban method It is considered a variant of the method just in timebased on the system “pull” or boot.

More in: Kanban

References

  • “Kanban” on Wikipedia.
  • “Just in time Method: what it is and what it is for” at the Industrial Postgraduate School (Spain).
  • “Just in time method: what it is, origins and how it is applied” in TOYOTA.
  • “Just-in-time manufacturing (business)” in The Encyclopaedia Britannica.