Andons In Lean Manufacturing

Andons developed as a natural offshoot of Jidoka (automation with a human touch) and quickly became an integral part of lean manufacturing with an emphasis on operator engagement, root cause analysis, and eliminating waste by aggressively attacking problems with permanent fixes.

Andon and Jidoka

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.

What Are the Origins of Jidoka?

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.

What Are the Principles of 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:

  1. Detect a problem on the line (automated).
  2. Stop the line (automated).
  3. Identify the root cause of the problem (manual).
  4. Implement a countermeasure and resume production (manual).

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.

What Is the Relationship Between Andon and Jidoka?

Andon lean is one tool within the broader spectrum of Jidoka. The Toyota Production System Guide defines two forms of Jidoka:

  • Design equipment to automatically stop when a problem occurs (mechanical Jidoka)
  • Equip operators with the means to stop production when they observe a problem (human 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 lean manufacturing Andon is essentially human Jidoka. Plant floor personnel are permitted (perhaps even obligated) to stop the production line if they perceive a potential quality issue or some other irregularity.

Andon and Lean

What Is an Andon in Lean Manufacturing?

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.

Andon, the line-stop indicator board hung above the production line, is a visual control…. When operations are normal, the green light is on. When a worker wants to adjust something on the line and calls for help, he turns on a yellow light. If a line stop is needed to rectify a problem, the red light is turned on. To thoroughly eliminate abnormalities, workers should not be afraid to stop the line.

How Does Andon Fit Into the Toyota Production System?

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:

Andons must call attention to any issues immediately, and they only fulfill their purpose if the root cause of the issue is detected and resolved. Any temporary solutions have to be avoided, as the point of stopping the line is to prevent recurrence of a problem. Temporary solutions create waste because eventually, the problem will crop up again, squandering the time and effort put into the first solution. There must be a relentless focus on fixing the root cause of problems for an Andon to fulfill its goal in terms of lean manufacturing.

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