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The Andon is a system of visual control allowing everyone to know immediately the operating state of the production (anomaly, advance/delay…).


The term andon, 行灯 in Japanese, is composed of the characters 行 ” go “, and 灯 ” lantern1, could result in “light where to go“. More generally, it is translated as ” lantern “.

From the toyotism and set up for the first time in 1957 in a Toyota2Factory, the Andon system enters into a visual management Logic and respect of the principle of Jidoka. It has the main challenges of increasing the responsiveness of teams to dealing with problems and facilitating team management.

The two types of Andon system

It is recognized 2 types of Andon3system. We find:

  • The Andon of anomaly: composed only of light green/orange and red, it allows to know whether the production takes place correctly or if a problem appears.
  • The Andon in advance-delay: composed of a panel having usually the production of the day to do and the state of progress, it allows to know whether we will be able to keep the deadlines or not.
Emergency level

Andon Anomaly

Andon in advance-delay

Priority 1

The line is off, you have to intervene

Production is overdue and we will not be able to keep the deadline

Priority 2

The line is not off but a problem requires rapid intervention

The line is overdue, and it is necessary to increase the resources to keep the deadline

Priority 3

Production takes place properly

Production takes place properly

Operating principle

The Andon system has a simple operation:

  • A light or alarm will come on when a problem is detected, either automatically by the machine or manually by the operator.
  • A planned team immediately intervenes at the location of the problem.
  • The team solves a problem:
    • Either the problem is solvable in the moment, less than 4 minutes4, the team works on it and solves the problem.
    • Either the problem is not solvable in the moment and therefore: either the Part is set aside and the production continues, or the line must be stopped and the team can call on other people in support.
    • The team validates that the problem is resolved and updates the Andon.
    • A backup is done on the activity taking into account the time of intervention and the type of problem.



The Andon system is not a tool that is decreed and implemented in the immediate future. An Andon system is already a willingness of management to establish a culture of quality and strong autonomy, which also results in changes of funds in the organization.

such as setting up other tools, the Andon system is implemented by following a PDCA of project management.

The information given by the Andon system must be understood by all.

The process of escalation linked to the Andon system must be clear and known to all.

In a test phase, you can use simple and manual systems to avoid development costs before you even have to validate the operation

Another application of the Andon: the Yo-i-Don system

Most commonly, the Andon system is used to indicate a line stop due to the appearance of a quality problem. At Toyota, we find another application of this system, the Yo-i-Don5system.

Translated as “Attention“, “Ready“, “go“, the Yo-i-Don is a visual system that will allow you to synchronize the workstations.

In this system, each workstation in the same value chain has a button. At the end of each operation, the operator validates his task by pressing a button. His andon then goes green, indicating that he can perform a new operation.

At the initial, all the workstation in the same line are green. At the end of the preset cycle time, if the operator has not pressed the button indicating the end of its operation, its workstation changes to red indicating a delay in the appearance of a workstation in red, the whole line stops until all the workstations go back to green. This ensures that all the workstations are synchronized and the line is balanced.


1-C. Roche (2013)-Small Lean guide for managers

2-R. The testifies (2013)-Supply Chain Management

3-O. Fontanille, E. Chassende-Baro, C. De Cheffontaines, O. Frémy (2010)-Lean Practice

4-J. P. Durand, P. Stewart, J. J. Castillo (2005)-The Future of chain work: an international comparison in the automotive industry

Y. Monden (2012)-Toyota production system: an integrated approach to Just In Time

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