​The thought process of Lean was thoroughly described in the book, “The Machine That Changed the World” (1990), by James Womack, Daniel Roos, and Daniel Jones.

In a subsequent volume, “Lean Thinking” (1996), Womack and Jones distilled these Lean principles even further to five:
1. Specify the value desired by the customer.
2. Identify the value stream for each product providing that value, and challenge all of the wasted steps (generally nine out of 10) currently necessary to provide it.
3. Make the product flow continuously through the remaining value-added steps.
4. Introduce pull between all steps where continuous flow is possible.
5. Manage toward perfection so that the number of steps and the amount of time and information needed to serve the customer continually falls.

In 2007, Womack and Jones simplified the five steps to these—Purpose, Process, People:

Purpose: The primary purpose of any organization and first step in any Lean thought process is to correctly specify the value that the customer seeks in order to cost-effectively solve the customer’s problems so the organization can prosper.

Process: Once purpose is clarified, focus on the process (value stream) used to achieve this objective. This is generally the combined result of three processes: product and process development, fulfillment from order to delivery, and support of the product and the customer through the product’s useful life. These primary processes are made possible by many secondary support processes inside the organization and upstream.

The ideal process is one in which every step (action) is:

  • Valuable: Meaning that the customer is willing to pay for the step because it creates value and would object if the step was deleted.
  • Capable: Producing a good result every time.
  • Available: Being able to operate whenever needed.
  • Adequate: Having the capacity to keep production in continuous flow.
  • Flexible: Permitting a range of products within a product family to move through a process without batching and delays.

People: After identifying the primary and support processes needed to create value for the customer, make someone responsible for each value stream. This value-stream manager must engage and align the efforts of everyone touching each value stream to move it steadily toward the customer while elevating performance from its current state to an ever-better future state.

Doing this requires: a master plan for the enterprise, often called strategy deployment; frequent improvement cycles for each process, often performed with A3 analysis (add link: http://www.thequalityportal.com/notes/A3Shook.pdf) embodying value-stream maps; and standard work with standard management for every step in each process.

Source: Lean Enterprise Institute: www.lean.org