Theory of constraints is similar to the concept of the adage, ‘a chain is only as strong as its weakest link’.  In a series of steps in a process, the slowest step controls the pace of the whole flow of the process. The process cannot go faster than the slowest step. This concept was made popular by the author, Eliyahu M. Goldratt in his book, The Goal.

Use: Considering that a Lean Initiative concentrates on reduction of waste and continuous flow, a team needs to understand the theory of constraints concept. Once the most constraining step in a process has been identified by the team, the idea of theory of constraints is to exploit this constraint to find ways of speeding up that particular step. Once that step has been optimized, the team will find ways to refine the next slowest step, exploit the step, optimize the step, and the process repeats until it’s no longer economical to refine any further.

Six Sigma Terminology