Value Stream Mapping
is a Lean
technique used to analyse the flow of materials and information currently 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" .
- Identify the target product, product family, or service.
- Draw 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.
- Assess the current state value stream map in terms of creating flow by eliminating waste.
- Draw a future state value stream map.
- Implement the future state.
Where is it used?
Value Stream Mapping is commonly used in Lean
environments to identify opportunities for improvement in lead time.
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.
Hand drawn versus tools
Value stream maps are usually drawn by hand in pencil to keep the mapping process simple and allow for simple correction. The idea is that a map can be drawn without delay while observing the target process in situation.
However, software tools are emerging as an alternative. A variety are available either as stand alone products or stencils/add-ons to products such as Microsoft Visio and Corel Corporation iGrafx FlowCharter.
Associated analysis methods
Hines and Rich (1997) defined seven Value Stream Mapping tools they are:
1 Process Activity Mapping
2 Supply chain responsiveness matrix
3 Product Variety Funnel
4 Quality filter mapping
5 Forrester effect mapping
6 Decision point analysis
7 Overall Structure Maps