Machined parts inspection and certifications
Choose the evidence your machined parts need: dimensional inspection, material records, certificates of conformance, first article inspection and organization-level certifications.
Separate part evidence from organization credentials
A material certificate, inspection report, certificate of conformance and ISO certificate answer different questions. Put the required evidence in the purchase specification so the supplier can quote and plan it.
| Evidence | It can show | It does not prove by itself |
|---|---|---|
| Dimensional inspection report | Measured features, instruments, results and acceptance against a drawing or model | That every unmeasured feature, later finish or future batch will conform. |
| Material test report (MTR) | Heat/lot identity and the material chemistry or mechanical results supplied for that lot | That the finished part has the same properties after machining, heat treatment or coating unless the scope says so. |
| Certificate of conformance (CoC) | A supplier’s declaration that the shipment conforms to identified requirements | The measurement details or laboratory results that are not included in the certificate package. |
| First article inspection (FAI) | A documented check of a representative first production article against requirements | Automatic approval for every design, process change or future lot. |
| ISO 9001 certificate | An organization’s certified quality-management system scope | A certificate for the part, material, aerospace program or customer specification. |
Write the acceptance package before the RFQ
“Inspection included” is too broad to price or verify. Name the drawing revision, critical features, sample size, instruments, reports and material or process records required.
| Brief item | Example decision | Why it matters |
|---|---|---|
| Drawing and revision | Drawing 1042 Rev C, units and general tolerance identified | Prevents a report being checked against an obsolete or ambiguous requirement. |
| Critical features | Datums A/B/C, hole position, flatness and sealing face | Directs measurement effort to what controls assembly or function. |
| Method | CMM, calibrated hand tools, optical system or special gauge as appropriate | The instrument and setup must suit the tolerance and feature. |
| Sampling | First article, every part, a defined sample or supplier quality plan | The acceptance burden changes the route and price. |
| Records | Report, raw data when required, MTR/CoC, finish or heat-treatment records | Makes the delivery package reviewable and traceable. |
Know when a document is enough and when a test is needed
Documents carry evidence only within their stated scope. If the part has a special material condition, safety function, regulated use or new process, ask what objective evidence is required.
An MTR normally follows the material lot or heat. It should be matched to the material used for the parts, with the applicable specification and condition visible. Do not treat a generic grade name or a supplier catalogue page as lot traceability.
A CoC can be useful as a shipment-level declaration, but it is not a substitute for the dimensional or material records the contract requires. If the CoC references a drawing, purchase order or specification, those references should be identifiable in the package.
FAI is a production-readiness record. AS9102 is a documentation standard for aerospace FAI; an FAI document does not make a supplier or part aerospace approved by itself. A customer may require a different first article format or additional approval.
Read ISO 9001 at the organization level
ISO 9001 is a quality management system standard. Certification is performed by an independent certification body and applies to the organization and stated scope; ISO itself does not certify companies.
| Check | Look for | Do not infer |
|---|---|---|
| Certificate holder | Legal organization name and issuing certification body | That a similarly named shop or subcontractor is covered. |
| Scope | Sites, activities and products/services included | That every process, material, location or special process is included. |
| Validity | Issue/expiry, current status and certificate identifier | That an old PDF proves current certification. |
| Customer requirement | The contract’s required standard and evidence | That ISO 9001 substitutes for ISO 13485, AS9100 or a customer-specific quality clause. |
A quality-system certificate can support supplier qualification. It does not replace the part inspection, traceability or acceptance records in the order package.
Use first article inspection when the risk justifies it
FAI is most useful when the design, process, supplier, site or production break creates a meaningful conformity risk. Define what triggers it and what approval means before production starts.
Design the mating pair
Clearance is the hole diameter minus the shaft diameter. Both parts contribute to the final fit.
Allow for the worst case
Minimum clearance = smallest hole − largest shaft. A nominal gap alone does not guarantee free movement.
Schematic illustrations; not to scale. Confirm the design for the chosen material, process and final use.
- Freeze the configuration. Identify the drawing, CAD, material, process, finish and any approved deviations used for the first article.
- Include the whole requirement set. A dimensional report can miss material, finish, heat treatment, cleanliness, marking or packaging clauses.
- Plan change control. A supplier, machine, site, material or process change may require a delta or repeat FAI under the customer’s quality plan.
- Define approval authority. State who reviews and accepts the report. Delivery of a report is not the same as customer approval.
Review the delivery package as a chain of evidence
A good package lets an engineer move from the order requirement to the exact part, lot, measurement and disposition without guessing.
| Step | Question | Evidence |
|---|---|---|
| 1. Configuration | Is this the released drawing and model? | Revision, PO and approved change record. |
| 2. Material | Is the supplied material tied to this order and condition? | MTR, heat/lot and process records where required. |
| 3. Manufacture | Was the specified process and finish followed? | CoC, finish/heat-treatment record and supplier declarations. |
| 4. Measurement | Were the critical features measured correctly? | Inspection report, method, instrument and results. |
| 5. Disposition | Are deviations identified and approved? | Nonconformance, concession or customer approval reference. |
Ask for the evidence without promising more than the program needs
Inspection and certification are valuable when they reduce a defined risk. Match the package to the product and customer requirement so a prototype does not carry an unnecessary production burden—or omit a requirement that matters.
For process, finish and quantity planning, use the On-demand manufacturing guide. For a machining-specific design review, see the CNC machining design guide.
Frequently asked questions
What is the difference between a CoC and an MTR?
A CoC is a supplier declaration that the shipment conforms to identified requirements. An MTR is a material-lot record containing the chemistry or mechanical results supplied for that heat or lot. Neither automatically replaces a dimensional inspection report.
Does an ISO 9001 certificate certify my parts?
No. ISO 9001 concerns an organization’s quality management system and stated scope. Part conformity still needs the drawing, process, material, inspection and acceptance evidence required by the order.
Does an FAI mean the part is aerospace approved?
No. AS9102 defines documentation requirements for aerospace first article inspection. The customer, contract and applicable quality system determine approval, and a first article does not automatically approve every future lot or change.
Should every CNC order include CMM inspection?
Not necessarily. Choose the measurement method and sampling plan from the feature tolerance, geometry, risk and customer requirement. A calibrated hand tool, optical system, gauge or CMM may each be appropriate for different features.
What should I request for a regulated prototype?
Request the records required by the program: released configuration, material traceability, dimensional results, process or finish records, deviations and any first article or customer-specific forms. Confirm the requirements with the responsible quality or regulatory team.
Sources and further reading
- ISO: ISO 9001 quality management systemsDefines an organization-level quality management system; ISO itself does not certify companies.
- ISO: certification and accreditationExplains the difference between a standard, certification body and accreditation.
- SAE: AS9102C — aerospace first article inspectionJune 2023 revision covering performance and documentation of FAI. Use the contractually required edition and customer requirements; an FAI is not a general aerospace approval.
- NASA JPL supplier portal QC20e: delivery of FAI recordsCurrent public JPL supplier clause showing customer-specific first article records, objective evidence and repeat triggers.
Define the evidence before the supplier defines the price.
Upload your CAD and drawing with the material, quantity, finishing and critical dimensions. Confirm the manufacturing route before production.