Every MIM shipment includes some form of certification document. The difference between a Certificate of Conformance (CoC) and a Certificate of Analysis (CoA) is significant — and accepting the wrong one can mean accepting parts without verified quality.
The difference:| Aspect | Certificate of Conformance (CoC) | Certificate of Analysis (CoA) |
|---|---|---|
| What it states | "These parts meet the specification" | Specific measured values for each requirement |
| Actual test data included | No — only a statement of conformance | Yes — chemistry, density, dimensions, mechanical properties |
| Legal standing | Relies on the supplier's word | Verifiable — data can be checked against the specification |
| Cost to supplier | Low — just a form | Higher — requires actual testing per batch |
| Commercial MIM | Common — accepted for standard parts | Also common — depends on customer requirements |
| Automotive MIM | Not acceptable | Required — actual test data per PPAP |
| Medical MIM | Not acceptable for implantable devices | Required — full material certification per lot |
- CoC: Acceptable for non-critical commercial applications, standard material grades, low-volume orders where the cost of per-batch testing is not justified
- CoA: Required for automotive (IATF 16949), medical (ISO 13485), aerospace (AS9100), and any application where material properties and dimensional conformance must be verified
- Material designation and specification (e.g., MIM-316L per MPIF Standard 35)
- Batch or lot number with full traceability
- Chemical composition with individual element values
- Sintered density (g/cm³ and % of theoretical)
- Mechanical properties (UTS, yield, elongation, hardness)
- Dimensional inspection summary (dimensions measured and results)
- Authorized signature and date
A Certificate of Conformance (CoC) only states that parts meet the specification — no actual test data. A Certificate of Analysis (CoA) includes measured values for chemistry, density, mechanical properties, and dimensions. Automotive and medical MIM programs require CoA with actual data. For non-critical commercial parts, a CoC may be acceptable.