PMAPs and Value Stream Maps – Which is Better?

Those of you who have worked with me in the past know the answer to this question. "The better tool depends on the problem you are trying to solve."

General PMAP Thoughts:

For me, the PMAP is the basis of all problem solving. It is quite simply, a diagram that you create to show the inputs and outputs to any process. And yes, everything is a process, so everything can have a PMAP --  from a librarian cataloging books, to a golfer analyzing their swing, to building a car.

Are you trying to reduce the costs in a call center? The output is a correctly answered question (quality), done in a reasonable time (cost). The inputs could include (and I am not a call center expert), computers, phone connections, software to help guide answers, the operator, their training, etc.

Are you improving the first time quality of an assembly process? The output is quality measured by FTQ. The Inputs could include, equipment, operators, procedures, materials, etc.

PMAPS can take several forms. The classic linear flow model and the 'swim-lane' model are two commonly used formats for a PMAP.

Classic PMAP

All PMAPs show the sequence of tasks which represent the series of steps in your project’s process. A process map includes steps that are needed to transform any activity’s inputs into outputs. The classic PMAP shows the process steps in a linear fashion, from beginning of your process to the end.

For example; Process 1 (place part in fixture) --> Process 2 (lower holding clamp) --> Process 3 (form part). Each of these individual steps will have inputs (fixture, part, operator, method, electricity) and outputs (part in fixture, part held secure, part formed to specification).

From the PMAP one can analyze how failure of the outputs directly relate to failure of one or more of the inputs. Using a combination of process experts, DOEs and Failure Mode Effects analysis, we can quickly begin to focus on "where to work" to improve our process.

See an example of a linear PMAP here (credit DMAIC Tools) → http://www.dmaictools.com/wp-content/uploads/2009/11/flowcharting0002.PNG

Swim Lane

Swim Lane Process Maps are practically the same as the classic PMAP, but it orders the process into "lanes." The Swim Lane shows the flow of your project through functional groups instead of just time based. My first step is "specify product" done by sales or a program team, the second process step is 'design product' done by Engineering, the third step is "Build Product" done by Operations, etc.

They use the same format for showing the Steps, Inputs, and Outputs as regular PMAPs. They differ only because they arrange the map so the rows indicate “who” does the process step, e.g., Engineering, Finance, Purchasing, etc. 

See example here → https://www.dropbox.com/s/xsup109y6uf6rfo/swim%20lane%20pmap.png

What is amzing to me is the number of poor examples of process maps and swim lane PMAPs is seen when one does a Google search. The all show simple diagrams of process steps, but almost none of them show the inputs and outputs. No wonder some firms place higher value to Value Stream mapping over PMAPs. It appears that not many people understand the power of the PMAP.

Value Stream Maps

It is my contention that a Value Stream Map is a sub-set of the Process Map. As the swim lane PMAP allows us to focus on the cross functional hand-offs throughout the process, the VSM allows us to focus on flow. By showing the process in a rough approximation of the actual plant (or office) layout, our inputs become flow oriented information (time to perform an operation, time sitting between operations, information/data flow patterns, materials flow patterns, and others. The outputs of the VSM are time related data, value added time and non-value added time. Of course one can also identify other areas of waste and search for ways to improve the process flow, reduce WIP, and other items.

See an example of a VSM here (credit velaction.com ) → http://www.velaction.com/lean-information/wp-content/uploads/2009/10/value-stream-map-sample.jpg

Summary

If you are a Six Sigma Black Belt, don't let the question "Are you familiar with Kaizen events and Value Stream mapping?" throw you off your game.  A Kaizen event is just a term for continuous improvement, but usually focused on process flow and waste improvement --often through the use of the specialized PMAP called the Value Stream Map. Of course you should still study this tool and work to create VSMs. They are different and demand some specialized learning. 

However, the most important thing for a Black Belt to understand is that everything is a process and everything has inputs and outputs. Also that failures in the inputs directly lead to failures of the outputs and these are the clues we need to solve the problem.

Coming up soon -- my favorite topic. Comparing data sets that may not be normal.

Are you enjoying this blog? Does it seem to have worth? Then pass this link to your Black Belt friends. Also please post comments below. I am always looking to improve.

Thanks,

John