The Essence of Muda

Publié le 13 décembre 2017

By Xavier Perrin (

Different mnemonics are used to help people remembering the 8 muda. Recently, I discovered a video using the acronym DOWN TIME for Defects, Overproduction, Waiting, Not utilizing talent, Transportation, Inventory excess, Motion, and Excess processing. TIMWOOD is another tip for recalling the 7 wastes of Toyota:  Transportation, Inventory, Motion, Waiting, Overproduction, Overprocessing, and Defects.
I personally do not recommend to use and teach that kind of tip for remembering the 7 or 8 muda as it induces people to view them as a list of meaningless words. Another issue with that kind of list is that it misses a very important point: overproduction is the worst muda and it should be cited in first (See: Why Is Overproduction the Worst Muda?).
Moreover, lean should definitely not be reduced to « eliminating waste » unlike it is often defined. Striving for eliminating waste is meaningless as long as the goal isn’t to « make value flow », which means that you have first « specified value » and then « identified the value stream ». These steps are the first three principles of the five lean principles which were proposed by James Womack* and Dan Jones, the remaining two being « pull from customer demand » and « strive for perfection ».
If you want to make your teams assimilate the essence of muda, I suggest to use a more powerful way to teach the 7 wastes of Toyota: bring them on the gemba (on the shopfloor), or ask them to remember the last time they went on the shopfloor, and make them visualize the material flow, the parts being processed. They will probably see a few parts being transformed by workers or machines. Not so much parts, in any case not more that the number of workstations. That transformation, if it has been required by the customer, is value added. Otherwise it is over-processing. Then they will see a lot of parts waiting to be processed between the work-stations. This is the waste of inventory, which has been caused here by the worst waste: overproduction. If they look closely at the work-stations, they will probably see that some parts are stored is specific locations as they do not comply with the specifications : this is the muda of defects. Some parts are transported from work-stations to work-stations or into the storeroom: this is the muda of transportation. Now, make them have a look to the operators: some of them are waiting because they cannot work, whatever the cause: they are observing the waste of waiting. Others are walking across the work-stations for grabbing something, this is the waste of motion. Finally, if they spend more time on the shop-floor, they will probably see engineers or supervisors discussing about manufacturing problems while standing close to operators, but without even consulting them about that problem: they are obviously facing the 8th muda, the waste of untapped intelligence of people.
Such an experience is a far better way to understand the essence of muda than remembering DOWN TIME or TIMWOOD.
Best lean thoughts.
(*) Lean Thinking: Banish Waste and Create Wealth in Your Corporation – James Womack and Dan Jones – The Free Press – 2003

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