Value stream mapping involves four steps. Defining the product family, creating a current state map, creating a future state map, and planning implementation. In this chapter, we’re going to focus on the last two steps.
Creating a future state map and planning implementation. The information used to create the current state map is combined with any insight gained from the physical evaluation of all activities. Along with the knowledge about lean improvement methodologies, these form the basis for imagining and designing an improved future state map for the system. To create a future state map, team members use various lean improvement tools, such as pull, takt time, kanban, setup reduction, and total productive maintenance. The future state map is where the team identifies creative solutions for all of the identified issues. The future state map shows specific changes that are required to the current state to achieve the envisioned future state of the value stream. The areas where kaizen events would improve the process are noted, and potential areas for improvement are circled on the map.
There are a few additional icons that are more commonly used in the future state map. The pull arrows are a major change from the current state map, where the flow is indicated by material flow arrows and push arrows. Kaizen bursts are represented by gold bursts. The signal kanban is typically used to represent the withdrawal from a supermarket. The kanban post is a location where the kanban cards are kept. And the production kanban is a signal to produce more.
Let’s say a Six Sigma team is mapping the future state of the value stream for an automobile manufacturing process. The results of the analysis of the value stream map showed several opportunities for improvement. Such as combining processes to create a better flow and eliminating batching of inventory between processes.
So let’s examine some of the elements of the future state map and what they mean in relation to this example. Two kaizen bursts were targeted, a design kanban and a design work cell kanban. The work cell was created for the fabrication, molding, and machining operations. Two bottleneck processes were also identified, machining and painting. The cycle time related to these processes is eight weeks, and a goal is set to reduce this cycle time. In the future state map, the flow of products between suppliers, the manufacturing process, and the customers will be based on the pull of customer demand. An inventory supermarket was used at the material receiving, starting, and ending points to reduce the total inventory and limit overproduction. In addition, a pull method was used between the sub processes for this purpose. A kanban post, represented by the goalpost symbol, was identified between the painting and inspection sub processes for the pickup of the in-process materials. Finally, signal kanbans, represented by the inverted triangles, were used next to the inventory supermarkets to signal a trigger, or a minimum point whenever the inventory levels in the supermarket between the two processes drop. The cycle time was estimated to reduce by 33%. And the lead time was estimated to reduce by 31%. The future state map is also expected to reduce the inventory substantially. More sophisticated forecasting, faster reporting, improved communication, and reduced inventory and monthly blanket orders cut the lead time and cycle time even further. The requirement for visual inspection was eliminated by using automated inspection, and the symbol was removed from the future state map.
The fourth and final step in the value stream mapping process is the plan implementation. This includes developing a step-by-step plan. When developing the plan, you use the value stream map to highlight the goals and objectives for the team. The team should include those working with the relevant processes to ensure buy-in. The plan also highlights the types of interventions needed. For example, these might be just do-it fixes that could be implemented in a day, kaizen blitzes that take two to five days, or even longer term projects. You’d then present the plan to management, secure the necessary resources, and finally, execute the improvement plan to reach the future state.