TPS Benchmarking

Subtle Shifts in the 7 Wastes of Lean

By Jon Miller Updated on April 3rd, 2021

As followers of the Toyota Way we try to stay we try to stay true to the practices, principles, and values that come out of that great company. There is always a lot more to learn about what we call Lean (TPS). Toyota is always taking kaizen to a higher level.
One of the core practices at Toyota (as well as any Lean company) is the relentless reduction of waste and non value added activities.

About 50 years ago, Taiichi Ohno of Toyota formalized this by identifying 7 types of waste in production.
We learned them, and we teach them as Overproduction, Transportation, Motion, Waiting, Processing, Inventory, and Defects. We have found that these categories are appropriate for describing all non-value activities, if you think deeply about them.
Some organizations have added an 8th, 9th, or 10th waste. We’ve never been tempted to tailor the Lean message for ourselves, and preferred to stick to the Toyota Way. I have to admit that we became rigid, and we were in for a shock when we learned that Toyota in North America (and in English language in general) expresses the 7 wastes as:

Conveyance (instead of Transportation)
Correction (instead of Defects)

At first we thought “The meanings are the same, words are a little different, probably just a poor translation.” But would Toyota make such an error? Let’s think more deeply about the differences in the two words.

First, ‘transportation’ conjures up images of forklifts, trucks, carts, and large quantities of materials being moved between production and storage facilities. ‘Conveyance’ is typically used to describe the movement of materials between adjacent machines on conveyors or materials presentation to assembly lines via carts, chutes, etc. When you visit a Toyota factory, you won’t see forklifts in the plant. Bicycles, AGV (automatic guided vehicles), tuggers, definitely doing something that looks a lot like transportation, but in routes according to a set sequence, timing, and specific content and quantity of material. It is a much more refined process that still adds no value, but perhaps deserves to be called “conveyance.”

As far as ‘defects’ vs. ‘correction’ the difference is obvious and huge. The word ‘defects’ conjures up images of bad parts, scrap, poor quality escapes, and rework. ‘Correction’ suggests that an error was caught before being passed on downstream and corrected. At a basic level it’s the difference between end-of-line inspection and in-process inspection, detection vs. prevention.
The Japanese words Toyota uses for the 7 wastes haven’t changed, as far as we know. Perhaps this is thinking too deeply on the meaning of two words. But it would be cool if the word choices in English were intentional, signaling that Toyota had ‘graduated’ from ‘defects’ to ‘correction’ and ‘transportation’ to ‘conveyance’ after 50 years of kaizen.

  1. Jack Parsons

    February 23, 2006 - 7:34 am

    Are wastes and non-value added activities the same? By the way, where did the often quoted statistic of typical Lead Time being 95% non-value added originate. This statistic appears in everyone’s presentation material, but the origin of this “fact” is never cited. By origin, I mean original author and “study”, “book”, “article”, “quoted teaching”…..etc.

  2. Jon Miller

    February 23, 2006 - 9:47 am

    I don’t know exactly where the statistic of lead-time being typically 95% NVA or waste comes from. It’s a statistic commonly associated with Value Stream Mapping and the “value added ratio” of value added time divided by lead-time. You may want to check on the LEI forums or NWLean if you have access to those, as someone there might know the exact origin.
    Certainly our own work has shown that value-added time as part of lead-time is much less than 5%, often fractions of a percentage.
    To answer your other question, waste is defined as anything that adds cost but no value to the customer. Non value added we define as adding cost, and not adding value but preventing a greater waste.
    For instance, inspection is considered to be NVA and not waste, since it prevents defects from escaping. If an inspection step was useless, it might be an example of a waste of processing, or there may be excess motion within an inspection process, so NVA can contain waste.
    Packaging materials are NVA and not waste since they prevent damage of products in transit. Paperwork is NVA and not to be waste since non-compliance with laws or loss of a quality audit trail would result in greater losses.
    Typically kaizen and Lean tools will get rid of a lot of waste right away, but NVA is much harder to minimize by attacking it directly. For instance you can reduce motion waste by bringing processes closer, but reducing packaging by putting the factory close to the point of consumption is not easy.
    They key thing to remember is that there’s not much point trying to speed up the value added, since it’s a very small part of what you do, and it costs more to do it. The same is true for NVA – very hard to make a big impact. Waste is much bigger and easier to reduce for bigger impact.

  3. Brian Johns

    July 14, 2011 - 6:00 am

    Ok time to set the record straight on this. The change from Ohno’s original 7 wastes to the TIM WOOD version occurred in Cooper-Standard Automotive in a small plant in Plymouth in the UK.
    In the late 90’s we were beginning to learn about lean from our customers and our market place and had created a Lean Enterprise Department to implement Lean in our factory.
    However as part of our learning process we were continually challenged by our MD on what we knew about lean tools, practices and principles. But as a group we could never remember all of Ohno’s seven wastes. We decided to fix that problem and create a Mnuemonic to help us so after a bit of brainstorming we came up with the name TIM WOOD. for the modified wastes of Transport, Inventory Motion, Waiting, Overproduction, Overprocessing and Defects.
    It worked, within a few short weeks everyone on the site knew the seven wastes and our version of what they meant. However it didn’t stop there. The concept of TIM WOOD rapidly spread beyond our business and our control through Ford, HOSCA and the particularly through John Bicheno’s book The New Lean Toolbox. To become imbeded in many lean businesses.
    So Toyota haven’t changed, their wastes are still the same and they remained the model we always used for the seven wastes. We just changed the list slightly so we could remember them. Our intenetion was never to change the meaning or the concept.
    The first time I realised this had happened was when I left Cooper-Standard and joined Siemens and realised TIM WOOD was here before me.
    The team that can be credited with TIM WOOD are Iris Tranter, Ken Gillard, Peter Bosworth and Myself and the change happened in the time it took us to have a coffee break.

  4. Brian Johns

    July 14, 2011 - 6:49 am

    As a follow up to my last post, The original reference we used to use for the seven wastes came from Masaaki Imai’s book KAIZEN first published in English in 1986 and he quotes Ohno’s seven wastes as:
    1. Overproduction
    2. Waste time spent at the machine
    3. Waste involved in the transportation of units
    4. Waste in processing
    5. Waste in taking Inventory
    6. Waste of Motion
    7. Waste in the form of defective units.
    The problem we encountered in back 1998 was that even at that time there were multiple translations of the seven wastes each one subtely different. I have earlier documents to Imai which translate the seven wastes from Japanese differently some with correction, some with conveyance we just decided to make it easy and standardise on TIM WOOD. we didn’t do much thinking about it.

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