If I were only allowed to pick one tool out of the entire Lean Six Sigma tool bag, it would probably be value stream mapping. A value stream map depicts the flow of resources and information as it goes across the entire value stream. It defines and shows us how value is derived and delivered from start to finish. We need to remember that waste disrupts value flow, and waste could be of all kinds. A current state value stream map may demonstrate the effort required, the time required, and defects and mistakes that occur in our present operation. We would also like to have a future state value stream map, to show the entire value stream in an ideal situation. We should recognize that value stream mapping is a technique to identify value and waste. And it gives us clues about how we can address these for continuous improvement. Using a simple example of value stream mapping using a popular technique, we can identify some basic information being captured. The flow of information is represented with single skinny arrows, with some kind of production scheduling pushing things to execution. An output may be a signal to push things through the process. We use a directional arrow to show the movement of the physical material, or the information coming from the supplier’s source.
Moving through the process and then off to some kind of transmit mechanism to our customer, who, in turn, is probably communicating, electronically or otherwise, the requirements to us to drive our production planning and control process. So it gives us a sense for the flow of information and material across our value stream. There are four steps in the process of analyzing the value stream. Step 1 is defining the product family. Step 2 is creating a current state map. Step 3 is creating a future state map. And step 4 is planning the implementation of improvements. To analyze a value stream, we have to start with first defining a particular product or family. And generally, you shouldn’t overshoot this too much or bite off more than we can chew. It’s usually a good idea to pick something very discreet. A particular piece of information we’re going to process, like an insurance claim. Or a particular part we’re going to produce, like a stamping that’s used in a mechanical assembly. We define this product pretty narrowly, and then follow it through the process. You kind of staple yourself to it by becoming the thing and marching through the process.
You capture what happens to it as you create a current state map. Once you’ve done that, you can do the analytics and move into analysis and identifying what could be done in the future state for a better future state and better results. The real benefit comes in when we get to the very end of the process. And we do the analytics, comparing the current state to the future state. If we evaluate the current state, we can identify five different steps. In the future state, we’ve noted a design work cell Kanban burst, and we’ve done a project to combine these three operations into one. We moved away from pushing things through the value stream, instead now pulling them through. The benefit can be quantified in the amount of effort and the amount of time. In the current state, the value add time is about 45 minutes per unit going through the value stream, and about 15 weeks of total lead time to get things through. In their future state, we drop that down to 31 minutes of value add time, which is about a 33% improvement in productivity. And we’ve reduced the time from 15 weeks to just 10 weeks of total lead time. What an improvement using value stream mapping can make.