If you run a series manufacturing line (a sequence of machines that each perform one step and hand the product to the next) you already know the frustrating truth, the line is only ever as fast as its slowest link. What's less obvious is which link that is, why it keeps changing, and what to do about it once you know. This is Theory of Constraints applied to the plant floor. It's not complicated in principle, but it's easy to get wrong in practice, and getting it wrong is exp