One of the most powerful Lean tools is called value stream mapping, a visual management method used 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. As with the other tools I’ve discussed, value stream mapping can be used to understand and document the production floor, in-office processes, hospital surgical wards, and, once again, even at home.
The first step in value stream mapping is to choose the process you want to improve, which will then be mapped. I recommend starting with a small, easily-defined process before tackling something more complex. For example, instead of trying to map an entire manufacturing operation, start with a specific work cell or operation. In an office environment, start with the accounts payable process instead of the entire financial management process. 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. This generally results 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, you use a large sheet of paper and draw the map 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. (You can use software too, but as I described earlier, I believe you learn more by writing by hand.)
The first step is to create the current state value stream map. Observe the process and detail each step in flowchart form. Traditional value stream mapping uses specific icons and symbols, which you can see on examples in the Resources section. Focus on material flow first, then look at information flow. Write down 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 you can calculate takt time as well as the total time the process takes.
Once everyone is satisfied that the value stream map accurately reflects the process, it is time to review, discuss, and envision ways to improve it. Ask yourself where waste is being generated, particularly in terms of time or idle materials and equipment. Determine which steps are value-added and which are non-valueadded. (Think about “value” from the perspective of the customer.) Remember that some steps may not be value-added from the perspective of the customer, but may still be required, such as paperwork required by regulations or additional testing the company is undertaking as part of a continuous project. You want the process flow rate to match to takt time driven by customer demand and make the process flow better to reduce waiting or transportation. Look for any bottlenecks and how can they be resolved. Remember the seven forms of waste and attempt to eliminate 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. Answer questions such as: 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 visually on an A3 report and monitor any changes you make via the daily accountability process that we will discuss later.