Often a forgotten pillar of the Toyota Production System, and in Lean manufacturing itself, Jidoka is actually one of the most important principles of Lean.
Sometimes known as autonomation, Jidoka means automation with human intelligence. The word itself was created by Toyota, starting with the term Jido meaning automation in Japanese and applying it to a machine built to make judgments, not just function on its own. It originated in the early 1900s when the founder of Toyota group, Sakichi Toyota, invented a textile loom that automatically stopped when a thread broke. This was an advancement on previous looms that required a worker to identify any faults or end up with mounds of defective material. It reduced the number of workers from one per machine to one worker for many machines. Further on Sakichi built looms which could identify when the spool was empty and replace it, without the need for a worker to stop the machine and replace it manually. Workers were only needed to step in to start the machines and monitor any that stopped operating.
This ability to identify a fault and stop working until it is repaired is an improvement in processes that lends itself to improvements in quality by eliminating defective root causes. It also lends itself to improved productivity, because one worker can have 5 machines working at once, even if one of those machines stop it is still 4 more machines operating per worker than previously.
The 4 steps that build the principle of Jidoka are:
- Machine identifies an abnormality
- Machine stops operating
- Worker fixers the immediate problem
- Worker investigates and correct the root cause
For More Than Just Machines
Jidoka applies to every aspect of the Lean process, not just the machines themselves. It is about building in quality improvements into the process, rather than inspecting at the end and starting again. It involves inspecting a product every step of the production journey and stopping that journey when an abnormality arises, to fix it and keep quality at a high standard. Although many companies fear this can slow down the production process, it actually reduces the amount of time spent quality checking at the end, and having to re-do if abnormalities are found. As each abnormality is identified along the way, and the root causes fixed, there is less call for line stops and productivity improves.
The Importance of Human Element in Jidoka
When used in conjunction with an Andon board, floor workers who identify a fault can pull a cord or press a button to stop the production cycle. The board will light up with a number associated with that machine and a supervisor will assist in identifying and possibly repairing the problem. If needed support can then be called in to repair the abnormality before the line is restarted.
Many machines produced today are built with autonomation incorporated, which is part of the solution in using Jidoka to improve productivity. The human element is workers taking action to identify the root cause and making the necessary improvements. These improvements are then documented, process documentation updated, and the changes communicated throughout the company to share the education with other processes.