The Lean Philosophy: It’s About “Time”

The Lean Philosophy: It’s About “Time”

Let’s revisit two age-old adages:

  • Time is money”
  • “Take the time to do it right”

Put these two together and you get to the age-old manufacturing belief that the higher the quality, the higher the cost. You must do things faster to reduce cost, but the faster you do it the higher the chance that a mistake will be made. The slower you do it the less chance of a mistake, but the cost will increase. And this was accepted thinking from time immemorial.

But after Henry Ford, and much later Toyota, we can now add two more age-old adages that had been forgotten or ignored by most businesses:

  • “Stop wasting time
  • “Do it right the first time

Put all four adages together and you have the philosophical basis of the “Toyota Production System” or today’s “Lean Manufacturing”. You can reduce cost and improve quality at the same time. It is all based around the proper use of time.

And what exactly is time?

According to the Random House Dictionary:

“The system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another.”

And the Merriam Webster Dictionary:

“A nonspatial continuum that is measured in terms of events which succeed one another from past through present to future.”

Although similar, the two definitions suggest slightly different concepts in my mind. The first definition makes me inclined to think “process”. And, for me, the second definition implies “flow”.

Taking all this one step further and I will say that the “Lean Philosophy” is based on “time” and is therefore a function of “process flow”. It is successful when “time” is minimized for the totality of “process flows” in a given system. You don’t necessarily minimize time by going faster; you minimize time by improving/balancing/optimizing the process flow within a system.

Thus the new objective is to maximize quality while being able to minimize cost at the same time. And you do this by minimizing the “time” consumed by the “process flows” within the given system. That is the basis of what I call “Process Thinking” and “System Thinking”.

And how do you minimize time? By not wasting it, of course. And as an example of this, see how all of Ohno’s seven wastes are, in fact, a waste of time:

  • Inventory is wasted time sitting.
  • Transportation is wasted time moving.
  • Over processing is wasted time (non-value added time)
  • Overproduction is time wasted (using time to provide what is not needed).
  • Waiting is time wasted.
  • Defects are wasted time.
  • Motion is time wasted

Time is the best metric for measuring the improvements resulting from the elimination of waste.

And this brings us back to the underlying principle that I outlined in my very first post, although from a completely different direction:

Thus the underlying principle behind TPS/Lean is the systemic creation of the shortest possible lead time for the continuous flow of materials and information in order to generate the highest quality and lowest cost.

But how does all this play out in real life situations? Here are a few examples that come to mind.

The target is to minimize time over the entire value stream (system). Time can be increased for any given process event or events if the time is reduced by a greater amount over the entire process flow (value stream).

  • In concurrent engineering, more time is taken at the beginning of any project by bringing all functions into the process right from the beginning. But time is significantly reduced for the entire process by having fewer problems in the downstream implementation phase of the development process.
  • Management is also a process. If time is spent upfront teaching problem solving, training, etc., then time is saved downstream when problems are solved by competent people on the line without management input
  • If an order is shipped to the customer ahead of time but is incomplete, the customer loses time waiting or tracking down the missing portion and the supplier loses time in responding to the customer.
  • Time is lost if a defect shuts down the line (poka yoke, andon, autonomation, i.e., jidoka) but more time would be lost if the defect is only discovered later downstream and the intermediate process events are wasted and additional time is consumed to rework.
  • Taking the time to fix a problem when it occurs will save more time than if the problem is allowed to continue and time is consumed via continued flow interruptions. Detection at the source is also more time efficient than detection downstream when the root cause is not as easily detectable.

In all cases quality is improved while costs are reduced – all the result of saving time.

After all, as they say in another age-old adage: “it’s just a matter of time”.


4 thoughts on “The Lean Philosophy: It’s About “Time”

  1. Another comment regarding time. Lead-time is a concept, not a metric. MCT is a metric that can be used to quantify lead-time. Regardless of whether it is MCT or something else, a metric for lead-time is needed so that people understand how to quantify current status and measure progress. Of course, I vote for MCT.

    1. It’s probably just a matter of semantics, but I have been measuring “lead time” since the early 90’s. I will be including data on “lead time” in my next post. Depending on what “lead time” I wanted to measure, I did it in several different ways. But it had to be “real” lead time and not some MRP system generated number. We probably went about it in similar ways.

Leave a Reply

Your email address will not be published. Required fields are marked *