Jidoka (Autonomation)
Build quality into the process by giving machines and workers the authority to stop production the moment an abnormality occurs
Jidoka, or autonomation (automation with a human touch), is the second pillar of the Toyota Production System alongside Just-In-Time. It means transferring human intelligence to a machine so that the machine can detect an abnormal situation and stop itself automatically. Unlike simple automation where machines run unattended and can produce hundreds of defective parts before anyone notices, autonomation builds in the ability to distinguish between normal and abnormal conditions. The concept extends beyond machines to the entire production line: if any abnormality appears, workers themselves should push the stop button to halt production. Stopping the line forces awareness on everyone, makes the problem visible, and drives permanent fixes rather than covering up issues.
- A machine automated with a human touch is one attached to an automatic stopping device that detects abnormalities
- If an abnormal situation arises, the worker is required to stop the line; there is no reason to fear a line stop
- A production line that never stops either has no problems or is hiding them; both are dangerous
- Stopping the machine when there is trouble forces awareness on everyone and makes improvement possible
- An operator is not needed while the machine is working normally; human attention is needed only when the machine stops
- Abnormalities will never disappear if a worker always covers for the machine when problems occur
- Autonomation eliminates overproduction and prevents the production of defective products simultaneously
- Distinctions between normal and abnormal operations must be clear, and countermeasures must always prevent recurrence
- Install Automatic Stop Devices on MachinesEquip all machines, whether new or old, with devices that automatically stop operation when an abnormality is detected. This includes safety devices, fixed-position stopping mechanisms, full-work systems, and baka-yoke (foolproofing) devices. The machine must be able to distinguish between normal and abnormal conditions without human monitoring.Pro tipBaka-yoke devices can take many forms: if there is a working mistake the material will not fit the tool, if there is an irregularity in the material the machine will not start, or irregularities in the earlier process are checked in the later process to catch defects.
- Empower Workers to Stop the Production LineEstablish a rule that workers themselves should push the stop button to halt production whenever any abnormality appears, even on manually operated lines. Install andon boards (line-stop indication boards) above the production line so that when a worker turns on a yellow light for help or a red light for a line stop, the location and nature of the trouble is visible at a glance.Pro tipWorkers must not be afraid to stop the line. Management must create a culture where stopping is seen as taking responsibility for quality, not as causing disruption.WarningIf workers are punished or pressured for stopping the line, they will hide problems rather than surface them, and autonomation fails.
- Investigate Root Causes and Prevent RecurrenceWhen a stop occurs, use the opportunity to understand the problem thoroughly. Do not simply repair the issue and resume production. Find the root cause, implement countermeasures to prevent recurrence, and update standard work procedures. If materials or machines are repaired without the supervisor being made aware, improvement will never be achieved.Pro tipUse the Five Whys technique to drill from the symptom to the root cause. A surface-level fix like replacing a blown fuse will see the problem recur within months.
- Transition to Multi-Machine OperationOnce machines can detect abnormalities and stop themselves, workers no longer need to stand watch over individual machines. Reassign workers so that one operator attends several machines, intervening only when a machine stops. This dramatically reduces the number of operators needed while improving both quality and production efficiency.Pro tipToyoda Sakichi's auto-activated loom allowed one young woman to oversee 40 to 50 machines. Start by having operators manage two machines, then expand as confidence and reliability grow.
The original jidoka device was built into Toyoda Sakichi's weaving loom. The loom stopped instantly if any vertical or lateral thread broke or ran out. A device capable of making a judgment about normal versus abnormal conditions was built directly into the machine.
In all Toyota plants, andon boards hang above the production line showing a green light for normal operations, a yellow light when a worker needs help with an adjustment, and a red light when a line stop is needed to rectify a problem. Any worker can activate these lights.
The concept originated with Toyoda Sakichi, founder of the Toyota Motor Company, who invented an auto-activated weaving loom that stopped instantly if any warp or weft thread broke. Because the machine could judge normal from abnormal conditions, no defective cloth was produced, and one young woman could oversee 40 to 50 automatic looms. When Ohno moved from textiles to automobile production, he asked why Toyota workers could only operate one machine each when textile workers managed dozens. The answer was that Toyota's machines were not set up to stop when machining was completed or when problems occurred. From this question, autonomation with a human touch was developed and became the second pillar of the production system.