The most common definition of jidoka is ‘autonomation.’ It is Japanese in origin, as are many specialized words in Lean. Jidoka traces its roots back to the early 1900’s at Toyota in Japan, then a textile manufacturing company. Sakichi Toyoda, an inventor and the founder of Toyota, developed a device that could detect broken threads in a loom and stop the machine from producing defective material. This concept, in which intelligence was added to machines, enabled companies to greatly increase the number of machines a single operator could run—with very little extra effort on the worker’s part. With jidoka, production becomes much easier for operators and much more profitable for companies.
The jidoka definition mentioned above (autonomation) is essentially automation with a human touch. But it has also come to mean more than that. It is about stopping whenever an abnormal condition is detected, fixing the defect, and then countermeasuring to prevent further occurrences. Many jidoka devices are combined with an andon light, or signaling device, to alert the operator of the abnormal condition. The purpose of jidoka is to separate people from machines, so an operator can do other tasks while the machine is running.
Companies often emulate Toyota and depict their production system as a “Lean house”. Jidoka is frequently depicted as one of its pillars. The other common pillar, JIT or just-in time manufacturing, and jidoka work together to create manufacturing excellence.
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Many automated machines today have jidoka built in. They stop when something goes wrong—a bit breaks, for example. Most of us even have a good example of this in our homes. Washing machines shut themselves off if they get out of balance of if the lid is opened.
Human processes have much less of this ‘built-in’. They often have a hard time detecting the abnormality, and frequently attempt to fix it themselves, rather than draw attention to the problem.
Imagine if you had to stay near your washing machine to listen for the signs of imbalance. You’d be extremely limited in what you could do and your time would be wasted.
Jidoka reduces the need to be near a machine continuously.
The basic steps of jidoka:
The machine detects the abnormal condition.
The machine stops itself.
Implement a stopgap.
Identify the root cause.
Quickly implement a permanent fix.
The steps of jidoka require not only that you detect abnormal conditions and stop production, but also that you implement both a stopgap to get production moving again, and implement a permanent solution to prevent future occurrences. Taiichi Ohno is credited with the following quote: “No problem discovered when stopping the line should wait longer than tomorrow morning to be fixed.” Simply put, every problem you identify is an opportunity to improve. Don’t squander those opportunities through inactivity.