Forget Lean…It’s About Process Stability and Flow

Rick Bohan

OK, I don’t actually want you to altogether forget about lean.  I do want you to get rid of the notion (if you ever had it) that lean is a tool bag of tricks and techniques for wringing a few bucks out of your manufacturing processes or for getting another percentage point of efficiency from your employees.  There are ways of achieving those ends if that’s what you want but lean ain’t it.  Rather, lean is all about creating a smooth, consistent, predictable flow of information and materials through your organization.  I found a couple of good articles that reinforce my thinking that I want you to check out.

Lonnie Wilson wrote one of the two best books I’ve seen on implementing lean, How To Implement Lean Manufacturing.  (Several years ago, I wrote a review of the book in which I gave it high praise but indicated that I thought it didn’t quite help the manager who wanted to answer to the question, “What do I do right now to get started?”  He got hold of my contact info and gave me a call, asking me about my critique because giving managers a good answer to that question was something that he very much had in mind when he wrote the book.  We had a great phone conversation and I’ve been of fan of his work ever since.)  He’s the author of both articles.

The first article, Outward Signs of Unstable Process Flow,  comprises a list of warning signs and indicators of poor process control that will eventually lead to failure if the symptoms and their root causes aren’t addressed.

I’ve seen most of these at one time or another within my clients.  (I haven’t had many clients, maybe none, who knew what the Cp or Cpk of their processes were and I’m not sure that it makes much difference.  Lonnie, on the other hand, is a big proponent of statistical methods, so there you go.)

My favorite bullet points are these two:

  • They not only have rework but also have lots of “inspect-sort-rework-resort-and-finally-ship” cycles in the production process.

  • Worse yet, many processes are actually designed that way.

One of my favorite “lean speeches” starts with “Every process is perfectly designed to get the results it gets.  That means, if a process gets bad results, it was designed to get bad results.”  Lonnie’s points don’t say quite the same thing but…almost.  I think his point concurs with my own view that too many manufacturing (and other) processes haven’t been carefully thought through and designed so as to be in control at (nearly) all times.

The second article, Wanna Sabotage Your Lean Effort?  Try This,  fits nicely with the first one. Lonnie states unequivocally that most lean initiative failures result from a failure to create stable process flow.  In his view, stable means predictable.  I would wholeheartedly agree.  I tell my clients that I’m more interested in consistency and predictability than I am in speed…if that “speed” is variable.

Here’s the central point of the second article:

[Most managers] try to implement the so-called lean tools, such as heijunka, kanban and SMED, without first attaining stable flow at takt.

This approach is doomed to fail.

And I would agree.  Don’t get me wrong, the tools Lonnie mentions can help an organization improve flow.  But most flow problems aren’t the result of “not enough heijunka”.  They are a result of poor design and poor management.


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