Jidoka definition in Lean perspective
Jidoka is known as “automation with a human touch” in Toyota Production System or Lean Manufacturing. The word jidoka traces its roots to the automatic loom invented by Sakichi Toyoda, Founder of the Toyota Group. The automatic loom is a machine that spins thread for cloth and weaves textiles automatically.
In 1896, Sakichi Toyoda invented Japan’s first powered loom called the “Toyoda Power Loom.” And, he put in a few creative controls into his powerlooms, such as automatic stopping device, which automatically stopped the loom when a thread breakage was detected, the warp supply device, and the automatic shuttle changer. Then, in 1924, Sakichi invented the world’s first automatic loom, called the “Type-G Toyoda Automatic Loom (with non-stop shuttle-change motion)” which could change shuttles without stopping operation. From then on, all these control features have been turned into key concept of Jidoka which is one of the key pillars in the original House of Toyota Production System (TPS) besides Just-in-Time (JIT) pillar.
Today, the Jidoka principle is practiced by all workers. When there is an abnormal situation arises the machine stops and the worker will stop the production line. Autonomation prevents the production of defective products, eliminates overproduction and focuses attention on understanding the problem and ensuring that it never recurs. It is a quality control process that applies the following four principles:
- Detect the abnormality or problem.
- Stop the operation.
- Fix or correct the immediate condition.
- Investigate the root cause and install a countermeasure.
Objective of Jidoka Principle
The main objective of Jidoka is that it makes possible the identification and solving of mistakes that occur in a process. Autonomation relieves the worker of the need to continuously judge whether the operation of the machine is normal; their efforts are now only engaged when there is a problem alerted by the machine.
The first example of this at Toyota was the auto-activated loom of Sakichi Toyoda that automatically and immediately stopped the loom if the vertical or lateral threads broke or ran out.
Today, the same Jidoka principle is applied to the production line. For example, in the production operations, a worker who is practicing Jidoka will self-inspect their own work, or source-inspect the work produced immediately before their work station is encouraged to stop the line when a defect is found. This detection is the first step in Jidoka.
Once the line is stopped, a supervisor or leader will immediately go and help solve the problems raised by the worker or machine. To complete Jidoka, not only is the defect corrected in the product where discovered, but the process is evaluated and changed to remove the possibility of making the same mistake again. One solution to the problems can be to insert a “mistake-proofing” device somewhere in the production line. Such a device is known as Poka-Yoke.
To understand more on the Jidoka definition and examples, watch the above Lean video taken from Toyota museum.