JI-DO-KA: A JAPANESE TERM FOR
AUTONOMATION

"Stop production so that production never has to stop” (Toyota proverb)

What is ”jidoka”?

The essence of "jidoka" is all in the above quote.

The term, used in the Toyota Production System (TPS) means equipping every machine and empowering every worker to halt the production process at the first sign of an abnormal condition.

If a defective part or equipment malfunction is discovered, the machine automatically stops, and operators stop work and correct the problem, rather than continuing produce.
This enables operations to build-in quality at each manufacturing process and to separate men and machines for more efficient work.

The common causes of defect are:

• Inappropriate operating procedures
• Excessive variation in operations
• Defective raw material
• Human or Machine error

According to the this principles, an operator is empowered to take control and stop the production line if he determines that something is wrong. It can be anything:

• a quality problem or alert
• equipment issue
• health and safety concern
• lack or overload of parts

"Jidoka" and the Japanese language

The Japanese term jidoka comprises three Chinese characters and is an untranslatable play on words.
The first character, "ji" refers to the worker herself. If he feels “something is wrong” or “I am creating a defect”, he must stop the line.
"Do" refers to motion or work, and "ka" to the suffix “-ation”.

Taken together "jidoka" has been defined by Toyota as automation with a human mind and implies intelligent workers and machines identifying errors and taking quick countermeasures.

The word "jidoka" sounds exactly like the standard Japanese word for automation but is written differently, adding the radical for human being to the character for move results in the character for work (you can see the difference in the above picture).

The pronunciation doesn’t change but the meaning and the connotation do. "Jidoka" as understood in Toyota includes the human being; classical automation does not.

To reflect the two meanings of the term “jidoka”, some authors choose to translate it by “autonomation”, a neologism, or “automation with a human radical added” or even “automation with a human touch”.

Autonomation in Toyota

So “jidoka” means to authorize the machine operator to stop the flow line so that defective pieces will not move to the next station. This concept minimizes the production of defects and reduces wastes.
But “jidoka” means also to understand the causes of problems and then taking preventive measures to reduce them. This is the improvement cycle that Toyota knows so well.

"Jidoka", in fact, is one of the two pillars (principles) of the Toyota Production System along with just-in-time. Without jidoka the whole temple of lean manufacturing is subject to collapse, which, in practice, means that the companies that ignore it fail to achieve the expected benefits and competitive advantage.

The jidoka pillar is often labeled "stop and respond to every abnormality." This is obviously much more than having a machine shut down. One very important as is that Toyota refers to every process, whether human or automatic, being enabled or empowered to autonomously detect abnormal conditions and stop.

The purpose of this concept is to free equipment from the necessity of constant human attention, separate people from machines and allow workers to staff multiple operations.

Sakichi Toyoda and "jidoka"

Jidoka was first used by Sakichi Toyoda, Founder of the Toyota Group, at the beginning of the 20th century.
Toyoda started designing and building wooden spinning machines. In 1894 he began to make manual looms that were cheaper and more efficient than existing looms.
Among his inventions was a special mechanism to auto¬matically stop a loom whenever a thread broke. This invention led to the concept of "jidoka".

Since the loom stopped when a problem arose, no defective products were produced. This meant that a single operator could oversee many machines without risk of producing large amounts of defective cloth.

"Jidoka" is very important for lean thinkers because Lean manufacturing dramatically increases the importance of building things right the first time. With very low levels of inventory, there is no buffer to fall back on in case there is a quality problem.