Something Lacking in the TPS House

People point out from time to time that there is something lacking in the TPS house used to explain the Toyota Production System. Typically it is represented with the two pillars of just in time and jidoka, with a foundation of kaizen, standardized work and heijnka. Although the wording differs from version to version, developing people and their creativity is in the center of the house.
“What about _ ?” People ask, with the _ being “fill in your favorite Lean tool or principle here.”
An article in Reliable Plant magazine points out the importance of Total Productive Maintenance for a Lean manufacturing system, and positions it at the foundation of the house. It’s a good article, making relevant points and offering different approaches taken by Toyota and Denso towards equipment stability.
But asking “Where does my favorite Lean, Six Sigma, TOC or other tool fit into the TPS house?” may be the wrong question. The goal should not be to fill the TPS house with as many tools and systems as possible (we are guilty of this also) but rather to extend the metaphor of the house to better understand the overall philosophy and management system at Toyota. Trying to fit more improvement tools or more of the non-production system prerequisites (sense of urgency, leadership, accountability, supplier partnerships, etc.) into the house itself just confuses people.
Perhaps a better way would be to zoom out from the house and look around, above and beneath it. Before we focus too much on the TPS house, we should seek a broader understanding by asking:
What about the foundation beneath the house (philosophy of management)?
What about the trees and yard around it (the environment)?
What about the neighborhood (community)?
What about the street and driveway to the house (marketing and sales channels)?
What about the utilities coming to the house (supplier)?
What kind of people live in that house (employees)?
Where is the garage, and the tool shed (by whom and how is the system maintained)?
What about the weather (socio-political environment around the business)?
When was the house built, for what reason, and by whom?” (history).
The answers to these questions may not provide practical everyday improvement tools, or solutions to problems. However these things all have had an impact on how the Toyota system came together in practice over the past half century, and they will have an impact on how you implement the Toyota Production System.

7 Comments

  1. Erik

    September 25, 2007 - 11:25 am

    Jon,
    Good point about filling in the house for the sake of filling it in.
    My sensei (from Toyota) recently walked us through building our own house. He stressed the importance of NOT putting the tools in the house. In fact, I had some on there and he instructed me to take them off. Instead he instructed, ask “How will we achieve JIT?”
    If a kanban system happens to be one of the tools to achieve JIT, then fine, kanban just happens to fit in the JIT pillar.
    The point here is that the pillar is not constructed of tools. The pillar is the ideal. Most tools will fall into one of the two pillars, but we should feel no compulsion to find a place in the house for all the tools up front.

  2. Jon

    September 25, 2007 - 11:36 am

    Exactly, Erik!
    Thanks for the great comment.

  3. Don

    September 30, 2007 - 5:46 am

    Actually Jon your base is incorrect it should be Process Stability – you must have a very strong base by which your business can build upon with some level of predictability over time. Standardized work, Heijunka, and Kaizen will help you get this stability. But also, you need to be delivering a product that is desired in the market place.

  4. Jon

    September 30, 2007 - 6:33 am

    Hi Don,
    The TPS house is meant to represent an ideal system to improve towards, not all prerequisites, outcomes or steps needed to achieve it.
    I would argue that Process Stability is a prerequisite for heijunka, standardized work, just in time and built in quality. Therefore, much like the elimination of waste, it does not belong in the “classic” TPS house.
    Heijunka and standardized work both address Process Stability, and the muri (variability) reduction aspect of kaizen addresses this also.
    The house as pictured above is the “classic” house at Toyota has depicted it. I am sure there are many “correct” versions depending on where you are on the Lean journey and what you need to accomplish.

  5. Alexander Zubov

    November 29, 2007 - 4:49 pm

    Jon,
    The most vital thing that is lacking in TPS house is respect for people. I would put it in foundation of the house. Without it every effort to put Kaizen into your culture will fail. Do you agree with me?

  6. Jon Miller

    November 29, 2007 - 8:41 pm

    I agree with you, but I would put the respect for people beneath the foundation. Don’t even start building a house without respect for people as the firm ground.

  7. Glen Cantwell

    January 24, 2008 - 8:50 am

    Personally I believe that the ideal ‘house’ should be free of any of these countermeasures – focusing on the process to expose the problems then reducing them through countermeasures is the first step. The next step should be to keep asking – why do we still have these countermeasure?
    I agree that people are vital, after all they live in the center of the house.