- It is a shock absorber for uncertainty.
- It shows you where flow ends…thus you must do pull.
- It shows you where you sense variability in your process.
- It insulates you from vendors who don’t deliver on time.
- It provides a tool for managing your entire process by observing buffer quanitities.
- It gives you a quantitative way to see changes in customer demand.
- It forces you to “declare” your process steps to others, making the process more transparent and visible.
- It allows you to measure your progress to the degree you can decrease buffer inventory sizes as a proportion of your total inventory.
WIP, in itself is not a waste. Too much of it is a waste. And paying attention to it is central.