(1) Value Stream Mapping is used to illustrate the flow and relationship between work processes. A key component of VSM is differentiating value adding activities from non-value adding activities. Reducing or eliminating non-value adding activities is of paramount importance and a principle goal of Lean Manufacturing. Upon careful and detailed examination of your processes through VSM, it soon becomes obvious where improvement opportunities lie.
(2) A pencil and paper tool used in two stages. First, follow a product's production path from beginning to end and draw a visual representation of every process in the material and information flows. Second, draw a future state map of how value should flow. The most important map is the future state map.
Value stream mapping is a lean manufacturing technique used to analyze and design the flow of materials and information required to bring a product or service to a consumer. At Toyota, where the technique originated, it is known as "material and information flow mapping". It can be applied to nearly any value chain. Implementation usually follows the following steps:
1. Identify the target product, product family, or service.
2. Draw while on the shop floor a current state value stream map, which shows the current steps, delays, and information flows required to deliver the target product or service. This may be a production flow (raw materials to consumer) or a design flow (concept to launch). There are 'standard' symbols for representing supply chain entities.
3. Assess the current state value stream map in terms of creating flow by eliminating waste.
4. Draw a future state value stream map.
5. Work toward the future state condition.
Value stream mapping has supporting methods that are often used in Lean environments to analyze and design flows at the system level (across multiple processes). Although value stream mapping is often associated with manufacturing, it is also used in logistics, supply chain, service related industries, healthcare, software development, and product development.
In a build-to-the-standard form Shigeo Shingo suggests that the value-adding steps be drawn across the centre of the map and the non-value-adding steps be represented in vertical lines at right angles to the value stream. Thus the activities become easily separated into the value stream which is the focus of one type of attention and the 'waste' steps another type. He calls the value stream the process and the non-value streams the operations. The thinking here is that the non-value-adding steps are often preparatory or tidying up to the value-adding step and are closely associated with the person or machine/workstation that executes that value-adding step. Therefore each vertical line is the 'story' of a person or workstation whilst the horizontal line represents the 'story' of the product being created. Value stream mapping is a recognised method used as part of Six Sigma methodologies. A key metric associated with value stream mapping is lead time.
One main purpose is to deepen one's understanding of a value stream by drawing a map of it. In current-state mapping this is done while observing the actual value stream in situation. Thus, value stream maps are often drawn by hand in pencil; to keep the mapping process real-time, simple and iterative by allowing for simple correction.