History & Lean fundamentals

Lean: The relentless pursuit of the perfect process through waste elimination

James Womack, a professor at MIT, built upon the methodology of Toyota Production System and outlined a 5 step process for applying the principles of the Toyota Production System.

This 5 step process is outlined in the book Lean Thinking.

1. Value can only be defined by the ultimate customer and only in terms of a specific product or service which meets the specific needs of the customer at a specific price at a specific time.
2. Value Stream outlines the set of action required to satisfy the customer need. A Value Stream Map serves as a tool for implementing lean by identifying all of the steps (both value added & non-value added) that bring a product or service to the customer. After identifying the non-value added steps, a future state map is used to define needed improvements to the existing process. The team then works to change the current state map to the future state.
3. Flow is the continuous movement of products or services from end to end through a process.
4. Pull is a system where nothing is done by the upstream process until the downstream customer signals the need. The system allows each process to withdraw what it needs, when it needs it, in the exact amount needed.
5. Perfection is a realistic goal once the first four principles of lean are in place.