There are some wonderful books on this subject.  I have no desire to compete with them, but I would like to break open this extremely important and underutilized tool.  In essence, let’s look under the hood and see what this thing’s all about.

Here are my goals:

1. Explain each segment of the Value Stream Map (VSM)  

   A. High Level Flow Chart

   B. Data Boxes

   C. Communication Flow

   D. Material Flow

   E. Value Add vs. Non-Value Add

   F. Importance to decision making

2. Explain the way to use this tool as an ongoing guide in allocating your Lean resources

What you see above is a high level flow chart.  It’s high level because it only depicts the major operations that take place in the making of a household fire extinguisher.  

The flow starts on the left with “Upset” and flows to the right.  We know this by following the directional arrows between steps.  It’s also the convention of Value Stream Map (VSM) construction

These directional arrows tell us one more thing.  Because they are straight and dashed, we know by VSM convention that material is being “Pushed” to, not “Pulled” by, the next operation.

At the “Upset” station, a steel billet, the size of a shuffleboard disk, is mashed into a shape resembling a bowl.  

Note: the “Upset” box contains a “3” at the bottom.  That “3” represents the number of workers required to perform the operation.  This convention is repeated throughout the flowchart.

Hundreds of the billets arrive in huge steel bins and are stored in front of the upset machine.  This  theme of large amounts of inventory in front of operations is repeated between almost all of the operations.  That trend will be discussed more below.

Once upset, the bowls are placed in other bins until full.  They’re then pushed to the “Form” operation where they are pressed into deep cylinders.  

Bins of the resultant cylinders are pushed to the “Weld” operation.

At the “Weld” operation, two halves of the cylinder are welded together, creating a single canister.  

Bins of canisters are pushed to “Pressure Test” where the canister is submerged in water, filled with air and tested to see if it holds pressure.  

Canisters that pass are inverted in racks to drip dry, then are pushed to “Drying.”

In “Drying,” the racks of canisters are placed in large ovens to bake off any residual moisture, before painting.

After being pushed to paint, canisters are hung on a conveyor and electrostatic paint is applied.  The conveyor then carries the canisters through a drying oven.

Dried canisters are removed, placed in racks, and pushed to “Auto-Fill.”

At auto-fill, canisters are removed and manually put into a machine that fills them.  The machine weighs the canister as it fills.  As soon as the proper weight is reached, the fill process stops.

Filled canisters are removed and placed on a conveyor.

The ”Conveyor Operation” consists of three contiguous operations: spray nozzle insertion, inner gas pressurization and test. 

Canisters that pass test are placed in a packing sleeve for shelf display.  Packing sleeves are inserted into shipping boxes.  Full boxes are sent to the “Warehouse.”

Pretty simple.  Nine steps.  

One last thing.  The symbols between each of the process steps give us additional important information.  Those triangles with an ‘I’ in them stand for “inventory.”  Below the triangle are the units of time it will take to consume that inventory by the downstream (receiving) operation.  Those units should be consistent throughout the VSM.

In my next post I’ll address the “Data Boxes.”