#61 1966 · Toyota Motor Corporation (assembly line) · Manufacturingincentive-flip
Toyota built the andon cord as every line worker's daily obligation, not a permission — with a team leader sworn to arrive within seconds and thank them for pulling it
the problem
Defects rode silently down the line unflagged by the worker who spotted them
background
Under Ford-style mass production, the assembly line was sacred: keeping it moving was the metric everyone was measured on, and a worker who stopped it — even to flag a defect — risked discipline or firing. At GM's old Fremont plant, for instance, stopping the line for any reason, including quality problems, was grounds for termination. Defects were caught downstream, if at all, after thousands of identical units had already passed the flawed step.
Toyota inherited the idea of self-stopping machinery from founder Sakichi Toyoda's 1896 automatic loom, which halted itself the instant a thread broke rather than weaving flawed cloth — the root of 'jidoka,' automation with a human touch. Rebuilding postwar with none of Detroit's capital, Taiichi Ohno extended the same logic to people: Toyota installed stop-button andons on the Crown line in 1955, and by 1966, when andon was installed at the Kamigo engine plant, Toyota's own corporate history describes the system as complete.
the move
Pulling the cord does not stop the line outright — it lights a signal and plays music, and a team leader, kept at roughly one per eight workers, is trained to arrive within seconds. If the team leader fixes the issue before the car reaches the end of its cycle-time station, the line never actually stops. Critically, the team leader's job is to thank the worker for pulling it, never to question or blame them — pulling the cord was built into training and management response as unconditional positive reinforcement, so it read as duty fulfilled, not failure confessed.
the payoff
The system succeeds by being pulled constantly, not rarely: at Toyota's Georgetown, Kentucky plant workers activate the andon roughly 2,000 times a week, which Toyota treats as healthy — problems surfacing, not hiding. When GM handed over its dysfunctional, strike-prone Fremont plant to Toyota to run as NUMMI in 1984 and had the same authority and response structure installed alongside the cord, absenteeism fell from about 45% to 3% and the plant matched Japanese-built quality within about two years — the clearest evidence the mechanism, not the cord, did the work.
what came after
Outside NUMMI, US automakers that copied the physical cord without the underlying obligation and response culture got little from it: one comparison cited by lean-manufacturing analysts found a Ford plant's cord pulled only a handful of times against Toyota's roughly 2,000 weekly pulls at a comparable plant. The contrast is now a standard teaching case in lean-manufacturing literature for why copying an artifact without its incentive structure produces nothing.
references
- [1]What Is an Andon Cord? How Toyota's Andon System Really WorksLean Blog (Mark Graban), 2012leanblog.org
- [2]Andon — TPS EncyclopediaArt of Lean, 2023artoflean.com