First-Article Inspection: Process, Documentation, and What to Expect
First-article inspection (FAI) is the dimensional, material, and process verification performed on the first part produced from a new setup, new tooling, or new production sequence. UTEC Industrial provides precision CNC machining services for large and oversized industrial components in the Pacific Northwest, with in-house heat treatment and induction hardening integrated into the machining workflow. This article explains what FAI entails, how it is structured, what documentation it produces, and when it should be required.
What is first-article inspection and why does it matter?
First-article inspection (FAI) is a formal verification that the manufacturing process, tooling, and setup are capable of producing a part that meets all requirements on the engineering drawing — before committing to a full production run. Without FAI, a shop could machine 50 parts, ship them, and only then discover that a setup error caused all 50 bores to be 0.005 inches undersize. With FAI, the first part is measured against every drawing requirement before the run continues, catching setup errors when only one part has been affected. The scope of FAI ranges from informal (a machinist checks the critical dimensions after the first part is complete) to formal and documented (all dimensions measured, all materials verified, all processes recorded, all results documented on a standard form — the AS9102 First Article Inspection Report or PPAP dimensional result report in automotive practice). For one-off and low-volume custom parts, informal FAI is common. For repeat-production parts with contractual dimensional requirements, formal documented FAI provides both the shop and the customer with documented evidence that the production setup is verified and traceable to specific tooling and process parameters (ASME Y14.5-2018).
What dimensions and features are inspected during FAI?
Formal FAI inspects all drawing requirements: every dimension, every tolerance, every geometric control (GD&T feature control frames), and every note that imposes a requirement on the finished part. This includes: all critical dimensions (bore diameter, OD, length, width, height) to the full drawing tolerance; geometric controls (concentricity, perpendicularity, flatness, runout) using the measurement method appropriate to the control (CMM for most GD&T, surface plate and indicator for runout, optical comparator for profiles); surface finish (profilometer measurement at specified locations); thread gauging (go/no-go gauges for threaded features); and any special notes (material grade, hardness requirement, coating, identification marking). For a 37-dimension crane wheel drawing, FAI documents all 37 measurements plus material certification and hardness verification on the first wheel of each new production run. This is more thorough than in-process inspection (which checks critical dimensions during machining) and shipping inspection (which checks critical dimensions on the finished part) — FAI is a complete verification of the entire drawing, not just the critical features (ASME Y14.5-2018).
What material and process documentation is part of FAI?
In addition to dimensional data, formal FAI includes: raw material certification (material type, grade, heat number, chemical analysis confirming the specified alloy) — UTEC provides complete raw material chemistry documentation for every order, which satisfies this requirement. Heat treatment records (if heat treatment is specified): time-temperature charts, furnace certification, and hardness verification results. Surface finish measurements at specified locations: typically profilometer traces printed and attached to the FAI record. Identification verification: that the part marking (part number, revision, date, heat/lot code) matches the drawing requirements. Process conformance verification: that all required operations were performed in the specified sequence — for a crane wheel requiring induction hardening, the FAI confirms that hardening was performed and the hardness meets the drawing specification before dimensional inspection. For customers who require first-article approval before production release, UTEC submits the complete FAI package (dimensional results, material cert, heat treatment record) and holds the production run pending customer approval.
How is FAI different from in-process inspection and final inspection?
The three inspection types serve different purposes and occur at different points in production. In-process inspection: checks performed by the operator during machining — measuring a bore diameter after each roughing pass, checking a facing cut with a dial indicator, or gauging a taper angle after the finish pass. In-process inspection prevents the machining of an obviously out-of-specification part from continuing. It is informal, rapid, and continuous. FAI: performed after the first complete part is finished — all operations complete, including heat treatment if applicable. FAI is formal, comprehensive, and documented. It verifies that the final part, produced by the complete manufacturing process, meets every drawing requirement. Final inspection: performed on every part (or a statistical sample) before shipment. Less comprehensive than FAI — checks critical dimensions and any special requirements, but not necessarily every dimension on the drawing. The distinction matters for customers: in-process inspection catches problems in real time; FAI proves the process is set up correctly; final inspection confirms the shipped parts meet critical requirements. UTEC performs in-process inspection on all critical features during machining and final inspection before shipment, with formal FAI available for customers who require documented first-article approval.
When should customers require FAI from their machine shop?
FAI is most valuable in four scenarios. New tooling or new setup: any time a shop runs a part for the first time with a new tool, new fixture, or new machining program — regardless of whether similar parts have been made before. If the program or setup has changed, the first part should be FAI'd before proceeding. Critical tolerance features: parts where a dimension is at the edge of the shop's capability (IT7 or tighter, or very close to a form or position tolerance that requires careful setup verification). High-value or long-lead-time parts: if a dimensional failure on part 10 of a 10-piece run means scrapping all 10 and re-machining, FAI on part 1 is cheap insurance. Contractual or regulatory requirements: defense, aerospace, nuclear, and medical parts often have contractual FAI requirements — PPAP in automotive, AS9102 in aerospace, or customer-specified first-article approval. For crane wheels that are repeat-run parts (same drawing, same material, same setup run repeatedly), UTEC performs FAI on the first wheel of each new production lot, confirming that the setup has been correctly established before committing the full billet stock to the run.
What should the customer provide to enable efficient FAI?
The customer should provide: a complete, current-revision engineering drawing with all tolerances, notes, and referenced specifications identified. If GD&T feature control frames reference datums, the datum structure must be clear enough for the inspector to understand which features are the datums and how to locate the part for measurement. Material specifications (either called out on the drawing or provided separately): grade, condition (annealed, normalized, hardened, etc.), and any certification requirements (ASTM, ASME, AMS). Process requirements: if induction hardening, annealing, or other processes are required, they must be specified on the drawing or in a referenced process document. Inspection equipment requirements: if the drawing requires CMM inspection, surface roughness measurement, or hardness testing at specific locations, this must be stated. Approval requirements: whether the customer needs to approve the FAI data before production continues, and how quickly they will review and respond. UTEC recommends customers provide full current drawings at quote stage — drawings with tolerances reveal the true machining complexity of the part and avoid scope changes after the job is quoted.
What is the format of a formal FAI report?
A formal FAI report documents each drawing requirement as a line item with the nominal value, tolerance, measured value, and pass/fail indication. The basic format: drawing bubble number or callout identification, nominal dimension, lower limit, upper limit, measured actual, and pass/fail. All critical dimensions are bubbled on a redlined drawing copy to ensure every requirement is identified and measured. Supporting records (material certifications, heat treatment records, surface finish traces) are attached as appendices and cross-referenced to the FAI. The report is signed by the inspector and authorized by the shop's quality representative, with date and the specific workpiece identifier (part number, serial number, lot number). For customers requiring formal AS9102 or PPAP FAI, UTEC submits reports on the appropriate form and retains copies for the production record. For customers with less formal requirements, UTEC provides the dimensional data in tabular form with the material certification and hardness test results as a complete, consolidated shipping documentation package.
- Dimensional Inspection Methods for CNC Parts — the tools used in FAI
- Quality Documentation for Machined Parts — broader documentation context
- Machining Tolerances: What to Specify — how tolerances drive FAI scope
References
- ASME Y14.5-2018: Dimensioning and Tolerancing. ASME.
- Machinery's Handbook, 31st ed. Industrial Press, 2020.
- SAE AS9102B: Aerospace First Article Inspection Requirement. SAE International.
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