By contrast, Toyota picks two or three suppliers for every component, and — rather than asking them to bid against each other — guarantees each a percentage of the business. Together, they develop a cost model that reflects the muda they can cut out of the process, protecting enough supplier profits to guarantee further joint creativity and innovation. This is possible, of course, only because the participants trust each other. The suppliers reveal more to lean-thinking customers about their operations and margins than a “poker-playing” company would ever find out.
True lean operations require a paradoxical kind of hierarchy: fierce top-down controls, but intensive bottom-up participation. The most durable lean companies tend to handle the paradox as Toyota does, putting authority over process mapping in the hands of a chief engineer whose decisions trump those of other executives — but who is charged with making sure that the process designs reflect the insights and observations of frontline employees. Thus, Tesco took stock-ordering responsibility away from store supervisors and installed a centralized computer-based system managed by the supply chain group to coordinate its intricate web of shipments throughout the chain.
“But the store managers gradually developed influence over the centralized decisions,” notes Mr. Booth, the former supply chain director. “It happened through trial and error. We visited stores day and night; we worked so that the store managers didn’t see us as an ivory tower or head office team. Instead, we were trying to make life simpler for them so they could move, in turn, to more customer-facing activity.”
Besides “value,” “pull,” and “flow,” Dr. Womack and Mr. Jones base their work on two other key precepts: “perfection” (an update of the idea of continuous improvement) and “mapping.” These precepts form the researchers’ answer to Toyota’s sensei. The lean mapping approach, in particular, represents the duo’s teaching method for translating the automaker’s production system to American and European companies: an elaborate set of do-it-yourself techniques that production teams can employ to diagram and diagnose their value stream. The authors first devised it when researching The Machine That Changed the World. Needing to compare many companies’ incompatible factories, they borrowed blueprints from a friend who ran a Renault plant and reconfigured these drawings into symbols that can be used to analyze flow and pull.
By now, their mapping icons have evolved to indicate every aspect of production operations, including the time that inventory remains in storage, transportation frequency (little truck and airplane images might be labeled “1x/day,” “2x/month,” or “3x/year”), and even computer connections. A map for a single product line could extend across a wall’s worth of butcher paper and contain hundreds of icons, notes, and subdiagrams showing quality levels at any given stage. The longer the stream, the more muda; as lean thinking takes hold, the map gradually contracts, getting smaller and simpler.
When Lean Thinking was first published in 1996, Dr. Womack and Mr. Jones were full-time researchers at, respectively, the Massachusetts Institute of Technology and the University of Sussex. Soon afterward, they started a pair of independent but connected nonprofit organizations. Dr. Womack heads the Lean Enterprise Institute in the U.S., which is based in his Brookline, Mass., home. Mr. Jones until recently ran the Lean Enterprise Academy in the U.K., which is based at Cardiff University. Today, both men have left academia. They make some of their living from consultation (though they say they do not charge consulting fees to any company they write about, for fear of compromising their research). They put on conferences, called Lean Summits, that routinely draw hundreds of executives who are keen to implement the methods they teach. And they sell thousands of copies of self-published manuals each year, written by Dr. Womack, Mr. Jones, and a group of colleagues, to help people apply their mapping methods and lean thinking techniques in real-world settings.