Glossary · Manufacturing systems
Scrap rate
Also known as: Scrap ratio, Reject rate
German: Ausschussquote
In manufacturing, the scrap rate is the proportion of produced units or material that fails quality requirements and cannot be reworked, and is therefore discarded or recycled.
- Manufacturing systems
- Standards
In one sentence
The scrap rate is the share of produced units or material that fails requirements, can't be reworked and is discarded.
Example
Of 5,000 castings, 150 are scrapped because of porosity, which gives a scrap rate of 3 percent.
How it applies
- Operation: Scrap is recorded with defect codes per order and shift; the scrap rate is a standard KPI. ISO 22400-2 defines a scrap ratio among its KPIs for manufacturing operations management.
- Cost and sustainability: Scrap wastes material, energy and capacity. Reducing it improves cost and environmental performance.
- Improvement: Scrap analysis by defect, machine and shift points to root causes such as Tool wear, material issues or settings.
- Documentation: Define the counting basis (units, weight, value) and whether start-up scrap is included. Scrap handling instructions should cover segregation, marking and disposal, so scrapped units can't re-enter the flow by mistake.
Scrap rate vs. first-pass yield
The scrap rate counts what is lost. First-pass yield (FPY) counts what is right the first time, so it also reflects rework.