Section 29 of 50
25. Design for Process Capability and Repeatability
Stable section ID: S05-CON-012-SECTION-29 · 25 content blocks
Products shall be designed around realistic process capability rather than nominal machine accuracy or ideal prototype results.
Process capability evaluation shall consider:
- Natural process variation.
- material variation.
- setup variation.
- tool wear.
- machine condition.
- operator variation.
- environmental effects.
- measurement uncertainty.
- batch-to-batch variation.
- maintenance condition.
Where a feature requires tighter control than the intended process can reliably provide, the design shall be reconsidered through:
- Tolerance adjustment.
- Interface redesign.
- alternative process selection.
- improved fixturing.
- additional process control.
- selective assembly.
- qualified secondary operations.
Selective assembly shall not be used to conceal an incapable process unless it is explicitly designed, traceable, and compatible with replacement requirements.
Repeatability shall be evaluated independently from accuracy. A stable biased process may require correction, while an accurate average with excessive variation may require redesign or capability improvement.
Designs should provide tolerance margin between expected production variation and functional failure boundaries.
Critical process outputs shall have measurable indicators. A process whose output cannot be verified directly may require qualification, parameter control, representative testing, or witness coupons.
Prototype success shall not establish production capability. Capability shall be demonstrated over representative time, materials, operators, equipment conditions, and production volumes.