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Rapid Recovery of a Failing EV Assembly Line
Background:
A Tier 1 EV supplier faced major quality challenges on an assembly line for an innovative EV component, with a Not Right First Time (NRFT) rate exceeding 50%. The high defect rate triggered excessive scrap, costly rework, and line stoppages at the OEM. Despite six months of support from another consulting firm, implementing over 100 changes across 60 stations, no meaningful improvements were achieved.Critical Issues:
- NRFT rate above 50%, significantly impacting quality and delivery
- High scrap and rework costs draining resources
- Frequent OEM line stoppages due to incoming quality issues
- Over 100 changes introduced with no improvement, creating system instability
- Lack of root cause clarity despite structured improvement attempts
Approach:
We started with a focused, data-driven strategy to identify and eliminate the failure mechanisms driving the high NRFT rate. We pinpointed the most problematic stations and rapidly deployed convergent diagnostics on each critical station. Within days, we uncovered causal explanations and implemented corrective actions on all of them, driving measurable improvements in a matter of weeks.Key Actions:
- Conducted Pareto analysis to isolate top contributors to NRFT
- Conducted in-depth convergent process characterizations for the highest-impact station.
- Deployed parallel diagnostic efforts across the top five NRFT stations.
- Developed and implemented targeted corrective actions within the first week
- Extended convergent diagnostics to remaining stations
- Maintained focused execution cadence to reinforce corrective measures and ensure process stability
Results:
- Significant performance improvement at the most critical stations within days.
- Complete causal explanations identified, revealing why earlier brainstorm-based changes were ineffective.
- Resolved issues spanned across automatic assembly, end-of-line (E.O.L.) testing, and burn-in failures.
- Eliminated recurring disruptions that had previously impacted OEM production.
- Replaced assumption-based fixes with precise, data-driven corrective actions.
By the Numbers
1 Week
To diagnose and correct the Top 5 stations
24%
Reduction in NRFT rate on the most critical station from 26% to 2% in less than one week
40%+
NRFT dropped for overall line from over 50% to below 10% within weeks
>3%
Final sustained NRFT performance improved
100+
Ineffective changes reversed or replaced with targeted, causal explanation-driven solutions