One of the most powerful Lean tools is called value stream mapping, which is a visual management method to document the flow and creation of value in a process. The definition of a value stream is all steps, value-added and non-value-added, that contribute to taking the process from raw materials (or raw data, etc.) to the customer – which can be another process. As with the other tools I’ve discussed, value stream mapping can be used on the production floor, office processes, hospital surgical wards, and, once again, even at home.
The first step in value stream mapping is to choose the process to be mapped, which will then be improved. I recommend starting with a small, easily-defined process before tackling something more complex. Sometimes, especially early on in a Lean transformation, it can be difficult to identify specific processes. I’ve seen way too many organizations take their first steps into value stream mapping by trying to map their entire organization, generally resulting in mass confusion, disappointment, and walls covered with sticky notes.
Once again, it is best to perform the value stream mapping exercise at the process so it can be observed in real time. Traditionally a large sheet of paper is used, drawing by hand with a pen or pencil. If more than one person is involved, it may be easier to use a whiteboard or a wall with sticky notes. There is software available, but as I described earlier, I believe you learn more by writing by hand.
Now it’s time to create the current state value stream map. Observe the process and in flowchart form detail each step. Traditional value stream mapping uses specific icons and symbols, which you can see on examples in the Resources section. Focus on material flow first, the look at information flow. Note the average amount of time each step takes and how each step relates to the others. Be sure to observe multiple runs of the process so you can also note variations in the process and any issues that arise. Also note the rate of customer demand so that takt time can be calculated. What is the total time the process takes?
Once everyone is satisfied that the value stream map accurately reflects the process, it’s time to review, discuss, and envision ways to improve it. Where is waste being generated, particularly in terms of time or idle materials and equipment? Which steps are value-added and which are non-value-added? Once again, think about “value” from the perspective of the customer, which means that some non-value-added activities may still be required. How does the process flow rate match to the takt time driven by customer demand? How can the process flow better to reduce waiting or transportation? Where are the bottlenecks and how can they be resolved? Remember the seven forms of waste and attempt to reduce them.
From that discussion, create a new future state value stream map incorporating the ideas for improvement. While doing so also create an action plan to change from the current state to the future state. What equipment needs to be moved? How does the process need to be rearranged? What visual controls will you use to monitor the new process? What is the timing and priority of these action items, and who is responsible? Document these required actions on an A3 report.
Implementation of these changes is monitored visually via the A3 report and the daily accountability process that we’ll discuss later.