Value stream mapping

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".[1] It can be applied to nearly any value chain.

Contents

Implementation

  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.[2]

Applications

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,[3] software development, and product development.

In a build-to-the-standard form Shigeo Shingo[4] 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 [5].

Metrics

A key metric associated with value stream mapping is lead time.

Hand drawn or software tools

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.

However, software tools can also be used. A variety are available either as stand alone products or stencils/add-ons to products such as Microsoft Visio, Dia and iGrafx.

Associated analysis methods

Hines and Rich (1997) defined seven value stream mapping tools[6] 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

See also

References

  1. ^ Learning to See: value-stream mapping to create value and eliminate muda by Mike Rother and John Shook ISBN 0966784308
  2. ^ Rother, Mike (2009), Toyota Kata, McGraw-Hill, ISBN 0071635238 
  3. ^ Graban, Mark. "Lean Hospitals," Productivity Press, 2008
  4. ^ A Revolution in Manufacturing: The SMED System, Shongo, Shigeo, Productivity Press, 1985, p5
  5. ^ "Value Stream Mapping" Article Source: http://www.isixsigma.com/index.php?option=com_k2&view=itemlist&layout=category&task=category&id=90&Itemid=222#
  6. ^ Lean Evolution: Lessons from the Workplace By Nick Rich, Ann Esain, Nicola Bateman

External links