The Lean River System – Part 1: What is It?

The Lean River System – Part 1: What is It?

Let’s go back, once again, to the basic foundation of the Lean/TPS system:

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.

Over the years I have noticed that the idea of “flow” in a processing environment (any system that contains discrete process steps to produce products or services) is harder to grasp for some people than for others.

To my surprise, I have found that engineers often have the hardest time with the concept of “flow”. Why? I am only guessing, but my theory is that engineers, by training, tend to focus on the individual process steps (especially if equipment is involved) rather than the entire process flow. In one case that I remember well, a process engineer was designing a piece of equipment that would produce enough parts in five minutes to meet an entire days’ worth of production. That equipment was never built.

Also to my surprise, I have found business majors and sales and marketing professionals were the best in understanding flow. Why? No equipment to worry about, maybe? They only have intangible processes to deal with on a daily basis? I really don’t know, but I still marvel at the stark differences I have found in people’s ability to grasp the importance of flow (and time).

Although I am myself an engineer, I was fortunate to learn all about flow early in my career. While still in college, I worked as a Co-op student with the chemical giant DuPont at a polyester synthetic fiber plant. Since DuPont was the creator of synthetic fibers back in the 1930’s, they were years (if not decades) ahead of their competition in this area of technical expertise. And they synthesized their polyester using a “continuous polymerization” process that fed directly to the fiber extruders. They were very proud of this achievement but I was too young and dumb to understand why.

But I soon found out when I graduated and went to work for their largest competitor (name withheld to protect the…. whatever). This company synthesized their polymer using a “batch” process. The worst part of my day, every day, was when we invariably had to switch from one batch of polymer to another. Startup waste was always huge as we tried to find the correct process parameters to make this batch produce the same quality product as the previous batch. What a waste of material, labor and, most importantly, time.

And that was how I first learned the importance of “continuous flow”.

But there were at least two engineers who grasped the systemic impact of “flow” and literally changed the manufacturing world. That would be Henry Ford and Taiichi Ohno. Of course Ford was the first, but Ohno took the concept to another level. Ohno’s vision is probably best illustrated in an interview he gave near the end of his lifetime. This interview can be found in the book Profitability with No Boundaries: Optimizing TOC and Lean-Six Sigma by Robert E. Fox, Reza M. Pirasteh. In the interview (pages 96 – 106) Ohno states:

“I had this idea of a fast, even-flowing river in which there were no dams that slowed the flow or rapids that sped it up. …It was to be a river system where ideally the only materials flowing were those needed for cars that customers were now buying. There would be no unneeded parts, yet we would always have the parts that were needed.”

Ohno started working on this river system right after World War II. He kept at it for almost 40 years. The concept of a flowing river was difficult to get other people to accept. He states:

“The biggest obstacle was not in finding ways to change over the machines quickly. It was in convincing our managers and workers that they should operate in this fashion. Once someone finished setting up a machine, they wanted to produce as many parts as possible – that was the efficient way. I had many struggles to persuade people that it may be efficient for that machine, but it was very inefficient for my river system. In the end it would create a lot of waste – wasted material, time, and effort in making parts that might never be used. Our people always looked at efficiency from their narrow viewpoint. I was looking at it from the viewpoint of the company. It was a long struggle.”

Sound familiar? Making the river flow was not the biggest problem, the biggest problem was getting people to understand “why” the river must flow. I think that is one reason why I see so little mention of flow in today’s discussions in books, articles, blogs, etc. about Lean. People still don’t get it! He later mentions one of the sources of this confusion:

“The cost accountants in Japan think just like they do in the Western world. They believe in all those things you mentioned [local efficiencies, big batches] and many more that are at odds with my river system. These beliefs were the biggest obstacle I had to overcome. …It wasn’t the cost accountants that were the problem, but all of those ideas about the efficiency of an operation. They were contrary to my desire to create an efficient system. I spent many years trying to persuade people to think differently, but without much success.”

But of course he was successful in the long run. I will be getting into cost/financial/management accounting later in this blog, but it is important to know that this is not a new issue to be dealt with. It has been around a long time. The key to understanding this issue is Ohno’s statement: “It wasn’t the cost accountants that were the problem, but all of those ideas about the efficiency of an operation. They were contrary to my desire to create an efficient system”.

It is the system as a whole that must be studied – the system is much more than the sum of its parts (operations). Ohno stresses this often overlooked conundrum when he states:

“You [Americans and Europeans] have superefficient assembly plants, but a very inefficient, wasteful system. … I think this makes the airlines and trucking industries profitable by causing your suppliers to regularly ship materials at premium prices.”

Take that!

And here is Ohno once again:

“The key to the Toyota Way and what makes Toyota stand out is not any of the individual elements…But what is important is having all the elements together as a system. It must be practiced every day in a very consistent manner, not in spurts.”

I think he means it!

Ohno also discussed the principle outlined at the beginning of this post that it is achieving “continuous flow” that creates highest quality, lowest cost and shortest lead time, not the other way around:

“There are two reasons we try to improve quality. If our product is better more people will buy it. Also, bad quality causes big disruptions in my river system. If a car must be returned to the dealer for repair, it disrupts the flow of my river system. The river system is supposed to flow only forward, not loop backward. … Improving quality wasn’t our primary focus. We tried to remove everything that disrupted achieving a fast-flowing river system. Machines that break down and workers that are absent also disrupts the flow. We had to reduce all types of disruptions to make our river flow quickly and smoothly.” [Emphasis mine]

Improving quality wasn’t his primary focus, his focus was on achieving flow in his river system. And to achieve flow, he had to remove any disruptions to that flow. And, of course, these disruptions constitute muri and mura which are the components of muda (waste). (See the “What is Waste” series earlier in this blog).

Which brings us back to:

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.

(Note that I have emphasized “systemic”).

And this is accomplished by eliminating waste. But I must again emphasize that the goal is not the elimination of waste. The goal is the achievement of continuous flow with the shortest lead time. Elimination of waste is just the means to an end – continuous flow. Elimination of waste without improving flow and lead time is a waste in itself. Much of today’s Lean efforts fail to make this distinction.

But how does Ohno’s vision of a river system fit in with all the buzzwords, slogans and other paraphernalia that is a significant part of the world of Lean that we are dealing with today? Can this river system thing help us in our daily journey to generate a real Lean transformation? Will it help others to grasp what it is we are trying so hard to do? All I know for sure is that it works for me. I hope the following posts will help you make up your own mind.

In my next post I will begin our journey down the Lean river system by contrasting it with the TPS House. What, you may say? How can you compare a river with a house? Actually the two meld pretty well together.

Stay tuned!


2 thoughts on “The Lean River System – Part 1: What is It?

  1. “And this is accomplished by eliminating waste. But I must again emphasize that the goal is not the elimination of waste. The goal is the achievement of continuous flow with the shortest lead time.”
    Wish I had said that!

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