Jidoka is one of two pillars of the Toyota Production System, the other being JIT (Just-In-Time). Jidoka translates to autonomation - automation with a human touch.
The goal of Jidoka is to design equipment to automatically stop when a problem is detected and to call attention to that problem. This frees operators to add more value by applying their skills and judgement to problem solving. The purest form of Jidoka also encompasses evaluating each problem for its root cause and preventing recurrences by implementing long-term fixes.
The origins of Jidoka can be definitively traced back to 1896 and the invention of an improved power loom by Sakichi Toyoda. Toyoda’s power loom had an innovative feature - it automatically shut down if the weft thread broke or ran out.
Taiichi Ohno, the driving force behind the Toyota Production System, started his career working at Toyoda Automatic Loom Works. As such, he was an expert in the power loom, and he later acknowledged that the design of the power loom was his inspiration for Jidoka.
Jidoka is intended to “combine automated processes with human intelligence and problem solving” (Toyota Production System Guide, Toyota PLC). In order to achieve this, it includes four elements:
Ideally, the first two elements are designed into the equipment (automation). The second two elements are performed by people (human touch). An automated system that detects problems and stops the line on its own is the true manifestation of Jidoka, as then human intervention is only needed to fix the issue, not to detect it.
Andon lean is one tool within the broader spectrum of Jidoka. The Toyota Production System Guide defines two forms of Jidoka:
The lean manufacturing Andon is essentially human Jidoka. In this interpretation, plant floor personnel are treated as experts in their domain and are permitted (perhaps even obligated) to stop the production line if they perceive a potential quality issue or some other irregularity.
The first use of Andons in manufacturing was at Toyota, where operators were encouraged to pull the Andon cord any time they observed a problem on the production line. This stopped the line, and supervisors and operators worked together to resolve the issue in way that would prevent it from happening again. This ensured smaller problems were resolved before growing into systemic issues.
One of the earliest authoritative descriptions that uses the term Andon in relation to manufacturing can be found in the book Toyota Production System: Beyond Large-Scale Production, written by Taiichi Ohno.
The Toyota Production System (TPS) centers around creating value and eliminating waste. By giving operators a way to immediately signal when they saw an issue on the line, Andons helped eliminate waste, especially because the focus was on long-term fixes that eliminated problems.
The focus on truly resolving issues could not be clearer in Shigeo Shingo’s description of Andons in his book A Study of the Toyota Production System: