Glossary · Manufacturing systems
Quality loss
Also known as: Quality rate loss, Defect loss
German: Qualitätsverlust
In OEE analysis, quality loss is the production time lost to units that do not meet quality requirements the first time, including scrap and units that need rework, and in some definitions start-up rejects.
- Manufacturing systems
In one sentence
Quality loss is production time lost to defective units, such as scrap and rework, in the OEE calculation.
Example
Of 10,000 molded parts, 200 are scrapped and 100 are reworked, so the quality rate is 97 percent.
How it applies
- Operation: Quality loss is captured by counting good and bad units per order or shift. The OEE quality factor is good units divided by total units.
- Definitions: Whether reworked units count as good or as loss, and whether start-up rejects are included, must be defined; common practice counts only first-time good units as good.
- Improvement: Root causes are often process instability, material variation or incorrect settings after changeovers. Inline inspection and quick feedback reduce the loss.
- Documentation: Document the defect catalog and counting rules, and link quality loss analysis to corrective actions in the quality system.
Quality loss vs. scrap rate
Scrap rate counts discarded units only. Quality loss in OEE usually also includes units that need Rework, because the time used to make them didn't produce good output first time.