Taiichi Ohno

Who they are

Ohno's work at Toyota produced the production system that most modern manufacturing method descends from. The vault holds him for two reasons, one narrow and one broad.

The narrow one is the 5 Whys. It is a diagnostic procedure: when a defect appears, ask why it happened, then ask why of the answer, and repeat until the mechanical cause surfaces rather than stopping at the symptom. Nir Eyal repurposes the method in Hooked to find the emotion underneath a user's behaviour instead of a fault on a production line. That transfer is clever and it is not validated anywhere in that book, and the difference matters: asking why five times about a machine gets you to a broken part, while asking it about a person can just as easily manufacture a tidy emotional story that is not true.

The broad one is credit. Ohno is the principal architect of the Toyota Production System, and his Toyota Production System: Beyond Large-Scale Production was published in Japanese in 1978 and in English by Productivity Press in 1988. The primary is not read in this vault, so nothing is attributed to it here beyond authorship and the standard account of its content.

Crediting only Ohno is its own error, and four other names belong with his. Eiji Toyoda, with him at Toyota through the development period. Shigeo Shingo, an external consultant to Toyota from 1955, who originated single-minute exchange of die, the setup-reduction method without which just-in-time does not function at all. John Krafcik, who coined the English word lean in "Triumph of the Lean Production System" in Sloan Management Review in the autumn of 1988. And James Womack, Daniel Jones and Daniel Roos, who popularised the term in The Machine That Changed the World in 1990.

This site keeps that lineage written down because it is routinely dropped. The vault records a 2026 business memoir that names lean at four separate points and credits none of those five names anywhere, and presents cycle time and touch time, both long-standing vocabulary from this tradition, as things the author learned or devised. That is recorded as a fact about the text, with no motive characterised.

Key papers

Ohno, T. (1978). Toyota Production System: Beyond Large-Scale Production. Published in Japanese in 1978 and in English by Productivity Press in 1988. Not read in this vault, and nothing is attributed to it beyond authorship and the standard account of its content.

The names that belong with his, and the two that supply the English vocabulary:

Krafcik, J. F. (1988). "Triumph of the Lean Production System." Sloan Management Review, autumn 1988. The paper that coined the word lean.

Womack, J. P., Jones, D. T., & Roos, D. (1990). The Machine That Changed the World. The book that popularised it.

Shigeo Shingo, consultant to Toyota from 1955, originated single-minute exchange of die, without which just-in-time does not function. Eiji Toyoda worked with Ohno at Toyota through the development of the system. The vault records no separate citation for either and none is supplied here.

Key ideas

The 5 Whys. Keep asking why of the previous answer until the mechanical cause surfaces rather than stopping at the symptom.

It was built to find mechanical faults. Applied to feelings, the same procedure can produce a tidy emotional story that is not true, and no source in this vault validates the transfer.

Just-in-time production and the seven wastes, both generally credited to him, developed at Toyota between roughly 1948 and 1975 with Eiji Toyoda.

Lean is Krafcik's word, from 1988, and Womack, Jones and Roos made it current in 1990. Ohno did not name the thing he built.

Shingo's setup reduction is load-bearing. Just-in-time does not work without it, and he is the name most often dropped after Ohno's.

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