Summary

Facilitates modeling your process by providing a mechanism for defining all activities in the process, the relationships between inputs and outputs in the process, and key decision points. Because you can use the value stream map (VSM) to focus on cycle times and waste identification, it is a key tool in all Lean projects.

Answers the questions:
  • How does value flow through the process?
  • What steps in the process add value and what steps do not add value?
  • Where are the bottlenecks in the process?
  • What is the average cycle time through the process?
  • What areas of the process exhibit the greatest need for improvement?
  • For a specific project, where does the process start and where does it end?
  • What does the actual process (not the assumed process) look like at the beginning of the project?
  • What are the inputs and outputs of each step in the process?
  • For a specific project, which inputs have little impact on the output of interest?
  • Does the process have steps that you can simplify or eliminate?
  • What does the actual process look like at the end of the project?
When to Use Purpose
Pre-project Identify potential projects by isolating areas of the process that need improvement. Which areas have high waste, large cycle times, bottlenecks, or low throughput yield?
Start of project Scope the project. Define the beginning and the end of the process segment that will be the focus of the project.
Mid-project Identify steps in the actual process, along with their inputs, outputs, activities, constraints, %VA, %NVA, %BVA, cycle times, and yields.
Mid-project Group brainstorming tool for setting aside inputs that have little influence on the output of interest.
Mid-project Group brainstorming tool for simplifying and/or eliminating process steps.
End of project Document changes in procedures in the improved process, update %VA, %NVA, %BVA, cycle times, and yields.

Data

No data requirements exist because you only use this tool to collect and organize data.

How-To

  1. As a team, determine where the process starts and where it ends, then walk through the process one step at a time.
  2. Identify data associated with each step of the process:
    • Activities (names of the steps in the process map)
    • Inputs (X-variables that can influence the output of interest, either directly or indirectly). The inputs are usually labeled as either C (controllable), N (noise), or SOP (standard operating procedure)
    • Outputs (Y-variables)
    • Process data (information that further defines the characteristics of a process such as the yield or DPMO at each step)
    • Lean data (information pertaining to resource utilization, cycle times, and so on, for each step in the process; typically used to help identify and eliminate waste in the process)
  3. Record the collected information, using the process mapping in Qeystone.

Guidelines

  • VSM (like process mapping) is a team effort. Your team should include people that have various jobs related to the process to help point out activities, inputs, outputs, or process data that may be missed otherwise.
  • Always walk through the process to ensure your VSM is accurate.
  • When using the VSM to identify potential inputs, focus on one small step at a time.
  • It is critical to gather good data for each step (for example, cycle times and yields).
  • Do not spend too much time trying to determine whether a step is BVA or NVA – both are considered waste.
  • The complete VSM generates the Variable Store Report (a list of process inputs with associated characteristics).
  • The complete VSM generates the critical path reports (to identify bottlenecks, for example).
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