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Book summary · Operations management · Intermediate

A Revolution in Manufacturing: summary and review

The SMED System

By Shigeo Shingo. First published 1983.

The short answer

This is Shingo's manual for cutting machine changeovers to under ten minutes. Split every changeover into work that needs the machine stopped and work that can be done while it runs, move as much as you can into the second group, then shrink what is left with better clamps, fixtures and extra hands. Faster changeovers make small batches affordable, which cuts inventory and lead time. It is a dense engineering text, best for engineers and supervisors on presses, moulds and machining, and best read knowing its Toyota history is disputed.

Read it if

  • Changeovers on your presses, moulding or machining lines force big batches.
  • You can change fixtures and clamps, so you need techniques, not only a procedure.
  • You want the original reasoning behind internal and external setup before teaching it.

Skip it if

  • Your changeovers are mostly cleaning or recipe changes; one critique reports a pharmaceutical plant that could not use the stamping techniques.
  • You need something operators can read quickly. Shingo wrote a 96-page operator edition.
  • You want a neutral Toyota history. This is Shingo's account of his own work.

When it pays off: Read it once you have timed a changeover on a machine where it limits batch size or scheduled hours. Before that it is more book than you need.

The core ideas, in plain language

  1. 1

    Internal and external work

    Internal steps need the machine stopped, such as swapping a die. External steps can run while it produces, such as fetching tools. Most shops mix the two, so the machine waits while someone walks. Separating them is the cheapest first gain.

  2. 2

    Convert, then shrink

    Ask of every stopped-machine step whether it must happen then; preheating a die or pre-setting a fixture off the machine moves work out. What remains gets quick clamps, intermediate jigs, two-person parallel work and fixed stops instead of trial adjustment.

  3. 3

    Order of attack

    The sequence is baseline study, separation, conversion, then streamlining. Cheap procedural moves come first and tooling spend last, so you do not buy clamps for steps you could have moved outside the stop.

  4. 4

    Small batches are the prize

    Short changeovers make small lots economical, which sources link to less inventory, less floor space and mixed production.

  5. 5

    What single minute means

    The name means under ten minutes, not sixty seconds. A 40-minute change cut to 9 qualifies; one cut to 15 may still pay.

How to use it on Monday morning

  1. 1

    Pick one changeover

    Choose the machine where long changeovers force big batches; the EPEI calculator shows how often each part can come round. Ask the setter to help film it, and say the method is the target, not them.

  2. 2

    Film the whole loss

    Film one changeover from the last good part to the first good part, including slow-down and restart, where researchers found losses a stop-to-start timing misses.

  3. 3

    Mark every step

    Watch the film with the setter and list each step and time on the SMED worksheet, marked internal or external. Fetching, walking, hunting for tools and reading paperwork are external; circle them.

  4. 4

    Stage the next one

    Before the machine stops, put everything the next changeover needs on a cart: tools, parts, material, documents, gauges. Run it from a checklist and time it. Do only this in week one.

  5. 5

    List what is left

    List remaining stopped-machine steps for engineering, such as clamps and adjustments. Write the new sequence as the standard before spending on tooling.

What to be careful about

  • The Toyota story is contested

    Isao Kato, 35 years at Toyota and Shingo's escort there, said in a 2006 Art of Lean interview that Toyota had cut die change times before Shingo arrived and that Shingo joined one 1969 workshop (1 hour 40 minutes down to about 40). He calls the four-hours-to-three-minutes story a misrepresentation, while crediting Shingo with the internal and external distinction. One insider, but a detailed account.

  • The evidence is anecdotal

    A 2007 critique by Sugai, McIntosh and Novaski (Gestão & Produção) says the data got no statistical treatment and the book does not separate general principles from gains owed to specific techniques. They also challenge its universal applicability.

  • It stops at the stop

    The same paper says SMED ignores run-down before the stop and run-up after it. On an automated line they observed, expected setup was 15 minutes, the pause was 30 and total lost time was 65.5. They also argue for equipment redesign.

  • Long and centred on dies

    A 1985 translation of an early-1980s text, over 350 pages, centred on dies and presses. Adapting it to other processes is left to you.

A Revolution in Manufacturing compared with Quick Changeover for Operators

Shingo developed this 96-page book from the longer one for frontline associates, with discussion questions. Use it to train a crew. Pick the full book to engineer fixtures or justify tooling spend.

Tools and templates on LeanSuite that go with it

Book details

Bibliographic details of A Revolution in Manufacturing
TitleA Revolution in Manufacturing: The SMED System
AuthorShigeo Shingo
First published1983. Published in Japanese as Shinguru dandori e no gententeki shiko (the year 1983 comes from Isao Kato's 2006 interview, not from a catalogue); English translation by Andrew P. Dillon, Productivity Press, 1985.
Edition shownEnglish translation by Andrew P. Dillon, first edition, Productivity Press, 1985
ISBN-13978-0915299034

Details checked against public records on 7 October 2026. Other editions have other ISBNs. We carry no affiliate links.

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