andon, Continuous Defect Eradication

andon is Applicable to Every System

The Toyota Production System is an interlinked system. andon and Seeking Perfection are an example of interlink.

Toyota found itself as a business in a poor country during the early 1950s due to World War II. Subsequently, between the availability and the cost of parts, they could not accept the large number of defects that American companies could accept. Taiichi Ohno, the brilliant Japanese engineer, devised a system to remove defects from manufacturing. The system was named andon. The andon system characteristics were:

  1. Every employee on the manufacturing line is a quality control inspector,
  2. Every employee has a responsibility to halt the assembly line if they discover a defect,
  3. They are then responsible for discovering the source of the defect,
  4. Finally, they contribute to rectifying the defect, and
  5. This, like Continuous Improvement, contributes to the learning organization.

If you believe that this has eliminated all of Toyota’s defects you’re wrong. Toyota’s aggressive Kata Continuous Improvement program implements a constant state of change. Though change is what moves you into the future it can also cause defects.

Toyota plants today execute andon stoppages about 800 times a year. If this number goes up they slow down the change they implement in their system. If this number goes down they increase the amount of change they make in their system.

The andon system feeds back into the Continuous Improvement system.

Another non-Automobile Example of andon

Hospitals HAI or Hospital Acquired Infections are the bain of any hospital. I published a YouTube video titled “The Best Patient Safety Program” that uses the concept of andon to halt any hospital patient process if the process deviated anyway from standard. The challenge comes mostly from nurses that detect a doctor’s nonstandard actions. Doctors are not used to being corrected by nurses. However, if you understand a deviation from standard behavior, then you should have the authority to halt the process.

A Learning Organization

I mentioned that there were two aspects of andon and the second was going back and determining the cause of the defect. This requires expertise out of your area that is learning. The more that individuals learn in an organization the smarter the organization becomes. If you want a smart organization, then require the person that discovers the defect to lead the team that goes back to determine the cause of the defect.

In Conclusion

In short, think of the andon system as a replacement for your quality control system. You replace a few people that test quality at the end of the line with everybody on the line testing quality. Everyone on the Toyota assembly line is responsible for quality. They detect defects at every step of product build. This really minimizes the impact of hidden defects.

Everybody in your system, is your system expert, about their job. Your System experts may surprise you sometime. Turn them loose. Toyota has been employing andon for decades and still averages about 800 andon shutdowns per year at each factory. Now they strategically place inventory on the assembly line sets that don’t stop the whole assembly line but a part of the assembly line and the rest of the assembly line can keep working. My earlier discussion on Seeking Perfection talked about Toyota’s Continuous Improvement program. Continuous Improvement introduces change into their assembly line. This change results in unanticipated problems. Those problems show up as andon stoppages. Toyota actually uses the number of andon calls as a metric for regulating the rate of change.

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