Mapping your value stream

by R.T. "Chris" Christensen

When I present seminars on lean manufacturing at the University of Wisconsin, the most frequently asked question I get on implementing these concepts is, “Where do I start?” The answer is simple. Start with a value map of your process to determine activities that add value to your deliverable. The map tells you how long it takes to do your process tasks and the time spent between tasks. You also pinpoint activities that are cost sinkholes.

After identifying where your time and money really go, then and only then do you apply tools from the lean manufacturing toolbox. That way, you apply your efforts to the cost or time elements you want to eliminate or minimize. 

If you want, stop reading this article here. You now have the answer to the FAQ. For those who are still with me, let us dig a little deeper.

It never fails that I get someone in class who says they got into “this lean thing” and it doesn’t work. They spent the past year working on some lean aspect — 5-S or 3-P or Six Sigma or single-minute exchange of dies (SMED) — and they didn’t save a thing. It was futility. 

Again, we see a self-fulfilling prophecy; another great idea went by the wayside. These concepts come and go. And, if we wait long enough or fail to approach the new idea correctly, it will fail, too.

To prevent failure, do a proper job defining the project up front. Lean manufacturing has that tool in place. That is where you must start. What we found in looking at organizations that started with Six Sigma or 5-S, etc., is they didn’t define the problem up front. They heard of the results these programs could generate and just applied them. What they failed to see was that in their operations, these tools might have little or no effect on their business.

The problem? They used a tool that isn’t needed or can’t be effective in the targeted environment. You get nothing from implementing a quick die change program when you have more than enough capacity to be able to build all the product you need, get it when you need it and have enough capacity time left to use wasteful setup procedures before manufacturing the product.

What you did was just generate more idle capacity. (There is an additional cost in the wasted time of the setup person, but you got no improvement in time to market.)

This is like implementing a quick setup program on an obsolete part, or implementing a Six Sigma quality program in an area where you do not have a quality issue.

What you need to do is analyze the core areas of your particular business that need the most help and then select the tool that gives you the best solution.

This is where you start with the implementation of a lean manufacturing concept in your organization. Start with the value map. Simply put, value mapping constructs a timeline for the process you want to study. The longer the line (usually expressed in days), the longer the process takes. 

Whenever an activity occurs, a vertical time bar is installed at the time of the activity. The longer the vertical line, the more it costs to do that activity. Now, and this is important, if the vertical line is below the horizontal timeline, the event is a cost and adds nothing to the sale price of the item. If the vertical line is above the horizontal line, it is a value-added activity and enhances the value of the item.

What you now have is a time bar that shows where and when your time and effort goes and if what you are doing is, in fact, adding to the value of your operation. 

Now, when you look at the areas of cost and time wasted, you can select the proper tool from your lean toolbox to get the desired results. If you see that you have a quality cost issue, then maybe a Six Sigma program is for you. If there is excess time and money spent on setup time, maybe a SMED program is a place to start. 

The point is, the value map identifies where you spend and/or waste cost and time. This then helps define the tool you want to use to reduce cost, or improve time to market, or reduce inventory and point out where you can get the most bang for your buck. 

R.T. "Chris" Christensen is the director of the University of Wisconsin School of Business' operations management program. If you have an inventory management question, contact Coach Christensen by phone at 608-441-7326 or e-mail cchristensen@execed.bus.wisc.edu. 

This article appeared in the June/July 2002 issue of MRO Today magazine. Copyright 2002

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