In one line: Deliver what the customer values with the least waste. Map the flow of value, remove everything that doesn’t add to it, and let customer demand pull work through the system.
Core idea
Lean grew out of the Toyota Production System and was named and popularized in the West by James Womack and Daniel Jones [1]. Its focus is waste (Japanese muda): any activity that consumes resources without creating value the customer would pay for. Lean is the natural complement to Six Sigma: Lean attacks waste and delay; Six Sigma attacks variation and defects.
How it works
Five lean principles (after Womack and Jones):
- Specify value from the customer’s point of view.
- Identify the value stream: all the steps that bring a product to the customer (see Value Stream Mapping).
- Make value flow without interruptions, queues or batching.
- Let the customer pull work, producing only when there is demand downstream.
- Pursue perfection through continuous improvement.
The classic forms of waste:
- overproduction
- waiting
- unnecessary transport
- over-processing
- inventory
- unnecessary motion
- defects
- unused talent
In practice
The program’s classroom exercise makes Lean vivid. Two lines of volunteers “manufacture” sticky notes, each station writing one word on each note before passing it along:
- One line works in batches of five, pushing work downstream.
- The other works one piece at a time, starting only when the downstream station’s space is empty (a pull signal).
Observers see the batch line build piles of work-in-progress, take much longer to deliver the first unit, and hide defects until late. The single-piece line delivers its first unit far sooner and exposes problems immediately. The same patterns appear in engineering work: design reviews batched at the end, drawings waiting in approval queues, and test results delivered all at once.
Questions to ask yourself
- Where does work wait longest in my team’s process?
- Which of the eight wastes is most common in our engineering flow?
- Are we pushing work downstream, or is downstream demand pulling it?
Connections
- Main tool: Value Stream Mapping. Partner method: Six Sigma. Roots: Total Quality Management.
- Flow and bottlenecks: Theory of Constraints. Visual management in development: Obeya.
- Capabilities exercised: Resourcefulness, Realizing the Vision, Responsibility and Urgency to Deliver.
Sources
- The five lean principles [1]
- Course module on TQM, Lean and value, including the batch-versus-flow exercise.