First article inspection in CNC machining checks whether a representative part from the intended production process meets its specified requirements. The useful deliverable is a traceable inspection record tied to the correct drawing, material, and manufacturing route. IAQG describes FAI as a consistent process for verifying product requirements.
For buyers, the first decision is what evidence you need before the next production step. Agree on the inspection scope, report format, and approval point during quoting. That makes the request clearer for the supplier and more useful for your team.
When should you request first article inspection?
Consider an FAI when you are introducing a production part, qualifying a new supplier, or making a change that could affect conformity. It is especially useful when a mistake would be expensive to discover after the batch is finished.
Ask yourself: What must we know before we authorize more parts?
For an early prototype, you may mainly need to check assembly fit and a few functional features. For a production component, you may need broader dimensional evidence, material records, and confirmation of specified finishing.
Choose the inspection deliverable around that decision. A focused prototype report can be appropriate, but it should not be described as a complete FAI if it omits required characteristics.
First-off inspection vs FAI: agree on the deliverable
A first-off inspection, also called a first-piece check, commonly helps the shop confirm a setup before continuing an operation. A buyer-facing FAI package documents conformity more broadly. Suppliers may use these terms differently, so request the contents rather than relying on the name.
Deliverable | Main purpose | What the buyer should clarify |
|---|---|---|
First-piece check | Verify the setup at a particular operation | Features checked, records retained, and remaining operations |
Dimensional inspection report | Record results for defined dimensions | Coverage, actual values, units, and measurement methods |
First article inspection report, or FAIR | Document the first article against applicable product requirements | Scope, supporting records, required format, and completion status |
Certificate of Conformance | Provide the supplier's declaration of conformity | Referenced requirements and accompanying evidence |
These documents can complement one another. A certificate alone does not show the measured results. A dimensional report may not account for material or finishing requirements.
Protolabs' CNC inspection options illustrate the distinction: standard inspection, dimensional reporting, and FAI have different coverage. Compare what is included in your supplier's quote.
Does your CNC order need AS9102?
AS9102 is an aerospace FAI standard, not an automatic requirement for every CNC order. It was developed for aviation, space, and defense, although other sectors can adopt it. IAQG explains its intended use.
If your contract requires AS9102, specify the applicable revision and customer requirements. A general inspection checklist does not replace the standard. SAE's AS9102C scope also states that its requirements complement customer and applicable regulatory requirements.
For a general industrial order, an agreed inspection package may meet the buying need without an AS9102-format report. Keep the description accurate: reviewing selected critical dimensions is not the same as completing a formal full FAI.
A full FAI addresses all required design characteristics. It does not mean inspecting every part in the order. Do not label a limited critical-feature check a partial AS9102 FAI without confirming the applicable requirements.
What to specify in the RFQ and purchase order
Include the inspection request in your request for quotation (RFQ). This lets the supplier account for inspection work, documentation, and any production hold before pricing the order.
Define the inspection scope and sample
Give the supplier:
- The controlling drawing, CAD model, specifications, and revision.
- The characteristics to report and any required standard or customer template.
- The number of samples and how each inspected part must be identified.
- Required material, heat-treatment, coating, or other process records.
- Whether actual measured values, gauge results, photographs, or physical samples are needed.
A ballooned drawing assigns numbers to characteristics so the report can map each result to a requirement. Where model-based definition controls the part, agree on an equivalent way to identify and account for requirements.
Use a consistent drawing package. Our technical drawing checklist explains how to communicate revisions, dimensions, threads, and finishes.
Agree on the inspection stage and production hold
State whether acceptance applies before finishing, after finishing, or at several stages. Some requirements need in-process evidence; others must be verified on the finished part.
Then define the release point. Requesting a report does not automatically instruct the supplier to stop production.
For example, you could agree that the supplier completes the first article through finishing, submits the report, and waits for written approval before machining the remaining quantity. Confirm whether that sequence is practical and how stock, outside processing, and delivery dates will be handled.
Name the person who can approve release and the process for handling deviations. Make sure these terms appear in the accepted order, not only in an informal discussion.
What should a first article inspection report contain?
Use the following as a practical buyer review checklist. The applicable standard and purchase order control the actual requirements.
Report element | What to check |
|---|---|
Part and sample identity | Part number, revision, inspected sample, and lot reference agree with the order |
Requirements | The report references the correct drawing, model, specifications, and approved changes |
Characteristic results | Results map to identifiable requirements, with units and acceptance limits where applicable |
Material evidence | Records support the specified grade and condition and are linked to the supplied material |
Process evidence | Required finishing, heat-treatment, or other records correspond to the inspected part |
Inspection evidence | Methods and equipment are suitable for the characteristics being verified |
Deviations | Missing, failed, or unresolved requirements are visible and have an authorized disposition |
Review and release | Completion status and approval match the agreed production-release process |
This broader view matters because dimensional conformity is only part of product conformity. Boeing's FAI planning requirements include evidence for design characteristics as well as material, process, and finish requirements.
Check how the measurements were made
A report needs credible measurements as well as complete rows. Ask how the supplier will inspect features that affect fit or function.
For a hole-location requirement, a diameter reading alone is not enough. The inspection method must address the location requirement and its specified references. A coordinate measuring machine, or CMM, can help with suitable geometric checks, but a CMM printout does not automatically constitute a complete FAIR.
For numerical characteristics, request actual results when useful for review. For thread gauges, visual requirements, or other attributes, an appropriate recorded acceptance result may be more meaningful than an invented number.
Check calibration status and measurement suitability for critical requirements. NIST explains that traceability involves a documented calibration chain and measurement uncertainty. Traceability alone does not establish that a measurement is suitable for its intended purpose.
In practical terms, ask the supplier to explain the method if a result is close to an acceptance limit. Resolve uncertainty about the measurement before deciding that the part is acceptable.
A mounting-plate example: inspect the condition that matters
Imagine an aluminum mounting plate with locating holes and an anodized finish. This is an illustrative buying example, not a customer case.
The buyer needs the holes to locate the assembly correctly after finishing. Checking the plate only before anodizing may leave that final condition unresolved.
Before ordering, agree on three points:
- Which hole requirements apply to the finished part?
- Which material and coating records must accompany the report?
- Must the buyer review a finished sample or assembly fit before releasing the balance?
The useful outcome is an agreed acceptance state. A report showing acceptable pre-finish dimensions should not be treated as evidence that every finished-part requirement has been met.
How to review the FAI before releasing production
Review the package in a consistent order:
- Confirm identity. Check that the report belongs to the ordered revision and identified sample.
- Check coverage. Look for omitted characteristics, missing records, and checks deferred to a later operation.
- Review exceptions. Examine failed results, unclear entries, and proposed deviations rather than relying only on a summary marked acceptable.
- Record the decision. Approve the agreed next step, request corrections, or keep the hold in place.
Keep the approved package with the order records. If a deviation is accepted, make its scope clear: an approval for one identified lot should not silently change future drawing requirements.
What affects FAI cost and lead time?
Ask for inspection and documentation costs to be identified in the quote. The workload depends on the part and the requested package.
Common drivers include the number of characteristics, difficult access, inspection programming or fixtures, required certificates, and customer-specific formatting. Shipping a sample or waiting for outside-process records can also affect the schedule.
A production hold introduces a separate timing question: how quickly will your team review the package? Agree on a realistic review window and who will respond if something needs clarification.
Compare suppliers on the same inspection scope. A lower quote may simply include fewer reported characteristics or documents. Our CNC supplier-selection guide covers how to compare the wider order scope.
When should an FAI be repeated?
Review the need for another FAI when a drawing revision, manufacturing change, or other event could invalidate the earlier evidence. The response may be a partial FAI, a full FAI, or another agreed verification activity.
For formal requirements, follow the applicable standard and customer contract. Boeing's planning guidance calls for evaluating changes that invalidate previous results and documenting the decision.
Avoid a blanket rule that every change always requires a full report. Agree on change notification and the review process before the first order.
Frequently asked questions
Is first article inspection required for every CNC order?
No; the need depends on the contract and the buying risk. A simple development prototype may need focused inspection, while a production or customer-controlled part may require a formal FAI package.
Is a CMM report the same as an FAI report?
No; a CMM report can be one part of the inspection evidence. An FAI package may also need material, process, and other conformity records.
Does an accepted first article guarantee the rest of the batch?
No; acceptance of the first article does not prove ongoing batch consistency. Agree on production checks, sampling, and any additional capability evidence needed for the order.
Can the first article be shipped before the full order?
Yes, if you agree on that sequence with the supplier. Define the sample, shipping arrangements, review time, and whether the remaining production must wait for written approval.
Agree on the release evidence before ordering
A useful CNC first article inspection request answers four questions: What will be checked? What evidence will be supplied? In what condition will the part be accepted? Who releases the next step?
PiPrecision is a Shenzhen CNC machining manufacturer supporting global customers with milling, turning, and finishing from prototype to production. Send your drawing and inspection requirements through our quote page so we can review the requested scope before quoting.