Tag Archives: Brink of Chaos

Entropy and Assignable Causes

Left alone, a process in the Ideal State will migrate toward the State of Chaos over time. Wear and tear of parts in use will lead to breakdowns and failures. Even mothballed machines cannot escape deterioration and decay caused by the environment. Entropy affects everything.

However, the effects of entropy can be repaired. Signatures of deterioration and failure made apparent by process control charts provide clues as to what repairs need to be made when. But, a process isn’t affected just by entropy. Other assignable causes keep it from operating in a predictable fashion. Replacing worn out parts might pull a process out from the State of Chaos back to the Brink of Chaos, but it’s just a matter of time before it returns to it.

Process managers, through the proper use of process control charts, must counteract the effects of entropy and assignable causes to help their processes achieve the ideal state and stay there. This is a never ending cycle.

Note: I learned this material from reading Dr. Wheeler’s writings. My post is intended to reflect my current understanding. None of the ideas herein are original to me. Any errors are my failures alone.

References

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The Brink of Chaos

Of the four states a process can be in (see “What State Is Your Process In?“) the most sinister state is the one where it is producing 100 percent conforming product but is operating in an unpredictable way. That is, the process is not under statistical control. Such a process is, in fact, on the brink of chaos. But, hold on. There is no nonconforming product, therefore there is no problem, right? It is easy to get lulled into complacency by this happy circumstance.

BrinkProcess

But because the process is not under statistical control it is impossible to predict what it will do in the next instance. Various assignable causes are affecting the process in an unpredictable fashion. The effect of these causes could very well be the production of nonconforming product without any warning. When that happens the process has moved into a state of chaos.

The only way to address a process on the brink of chaos is to use process control charts to identify assignable causes and eliminate their effects one-by-one and bring the process under statistical control. You can then start other improvement efforts like moving the process mean to the process aim and reducing the process variation by minimizing the influence of common causes affecting the process.

Note: I learned this material from reading Dr. Wheeler’s writings. My post is intended to reflect my current understanding. None of the ideas herein are original to me. Any errors are my failures alone.

References

What State Is Your Process In?

You can take one of two approaches to controlling the quality of your product. Once manufactured, you can compare it against its specifications and sort it as either conforming or nonconforming. This, however, will guarantee the greatest degree of variability between units as anything within specifications is considered acceptable. Alternatively, you can work to run the manufacturing process as consistently as possible to produce units that vary as little as possible from one another.

There is no path to improving performance with the first approach where you sort manufactured product as conforming or nonconforming. However, there is a clear path to improving performance through the use of process control techniques introduced by Dr. Walter Shewhart. But, how do you gauge improvement? One measure is achieving a state of statistical control for the process so that its behavior is predictable. Another measure is the manufacture of 100 percent conforming product by the process.

When these two measures are taken together, there are four possible states a process can be in (see figure below): The process is

ProcessState

Note: I learned this material from reading Dr. Wheeler’s writings. My post is intended to reflect my current understanding. None of the ideas herein are original to me. Any errors are my failures alone.

References