Lean Six Sigma Black Belt
A Black Belt runs Six Sigma's DMAIC process, Define, Measure, Analyse, Improve, Control, to cut defects and variation out of a process using data rather than opinion.
Five boxes run left to right, Define through Control, each one feeding straight into the next.
Reach for this when…
- A quality problem keeps recurring and every fix so far has been a guess.
- You need a rigorous, data-backed case before spending on a process change.
- Defect rates are known but nobody can say which step is actually causing them.
How to run it
- Define the problem, the customer's requirement, and the project scope.
- Measure the current process and collect real data on the defect.
- Analyse the data to find the actual root cause, not the obvious one.
- Improve the process and test the fix on a small scale first.
- Control the gain: build in monitoring so the process doesn't drift back.
A worked example
Situation. Avi Ben-David ran Ben-David Axles, an axle-parts supplier near Tel Aviv, Israel, where 4% of a batch failed final inspection and the floor blamed the steel supplier.
Applied. A Black Belt project measured tolerances at every machining step, and the Analyse phase showed the real cause was a worn fixture on one lathe, not the raw steel.
Result. Replacing the fixture and adding a control chart on that station cut the failure rate to under 0.5%, and the supplier was cleared.
The catch
DMAIC needs a process stable and data-rich enough to measure, so it struggles with one-off problems or genuinely new processes. Certification culture can also turn it into a status game, and a Black Belt with no shop-floor trust will get told what people think they want to hear.
If Measure and Analyse take a day and Improve gets three months, the project was decided before the data came in.
Origin: Motorola (Six Sigma, Bill Smith, 1986); Toyota Production System (Lean); the combined Lean Six Sigma methodology is generally credited to Michael George's consulting work in the early 2000s, not to General Electric, though GE's own Six Sigma rollout under Jack Welch did much to popularise the underlying discipline.