What the Theory of Constraints is
The Theory of Constraints (TOC), created by Eliyahu Goldratt in the book The Goal, starts from the idea that every production system has a bottleneck — a resource that limits the system's total capacity. Improving any step other than the bottleneck doesn't increase overall output; only improving the bottleneck step increases what the whole system produces.
The 5 focusing steps
Identify the constraint
Find the resource (machine, person, policy) limiting the system's capacity.
Exploit the constraint
Make sure the bottleneck is never idle due to missing material, setup, or unnecessary breaks.
Subordinate everything to the constraint
Pace every other process to the bottleneck's rhythm, avoiding overproduction upstream of it.
Elevate the constraint
Invest in additional capacity at the bottleneck if the previous steps aren't enough.
Repeat the cycle
When the bottleneck moves (because it was resolved), the cycle restarts with the new constraint.
An hour lost at the bottleneck is an hour lost for the entire system. An hour lost anywhere else is just an illusion.
How TOC and Lean complement each other
While Lean seeks to eliminate waste across the entire flow, TOC helps prioritize where to invest first: the most profitable improvement effort is almost always at the bottleneck step. Many teams use Value Stream Mapping precisely to visually locate that constraint before applying Lean tools.
Want to locate your process's bottleneck?
Read the complete Value Stream Mapping guide.
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.