Improve Phase
Purpose and deliverables
Improve selects, tests, and implements solutions that address verified root causes. Deliverables: prioritized solutions, a pilot, and an implementation plan with owners and dates.
Core concepts
- Solution selection: impact/effort matrix, Pugh matrix, cost-benefit; solutions must map to root causes.
- Lean improvement tools: 5S, kaizen, kanban, poka-yoke (error-proofing), SMED (setup reduction), standard work, cellular layout, TPM.
- Design of Experiments (DOE): factorial designs to test multiple factors and interactions; screening designs when many factors exist.
- Pilot and simulation: test small before full rollout.
- Change management: communication, training, addressing resistance.
- FMEA to anticipate failure of the new process.
Traps in questions
- Choosing a solution that does not address the verified root cause (solution jumping).
- Confusing poka-yoke (prevents error) with inspection (detects error).
- Ignoring interactions between factors - one-factor-at-a-time misses them.
- Skipping the pilot and rolling out untested changes.
- Forgetting to update standard work and documentation - improvement decays without it.
Rule of thumb
Cause → solution, one-to-one. If a proposed fix cannot be traced to a verified root cause, it is a guess. And prefer error-proofing over training or inspection, which are weaker controls.
Worked example
Root cause: parts loaded backwards. Training reduces but does not eliminate errors. A poka-yoke - a fixture that only accepts the part one way - prevents the defect entirely and is the stronger solution.