This article is part of the CNC Tolerances & Quality Control Guide: GD&T, CMM, Cpk, PPAP on CNX Precision.
A first article inspection proves that a new part meets its drawing. It is the most complete check in CNC machining. In short, first article inspection verifies every feature before production starts. Buyers use it to approve tooling, process, and quality. This guide explains the process, the report, and the standard behind it.
Many industries demand this inspection. Aerospace, medical, and defense use it as a gate. If the first part is right, the batch can follow. If the first part fails, the process needs work. Therefore, FAI saves time, material, and risk.
What Is First Article Inspection?
First article inspection, or FAI, checks the first good part from a new setup. It compares every dimension on the drawing with the measured value. The goal is simple: prove the process can make the part correctly. In addition, FAI records the material, the tooling, and the machine. This record becomes the reference for the whole order.
An FAI is not a random sample. It is a complete verification. For example, we check holes, threads, surfaces, and GD&T features. We use CMMs, calipers, micrometers, and gauges. In addition, we record the inspector, the date, and the instruments. As a result, every number in the report is traceable.
Some projects allow a partial FAI. The customer may list only critical characteristics for review. In addition, a delta FAI covers only changed features. These options save time on repeat work. However, a full FAI remains the safest choice for a new design.
Why First Article Inspection Matters
FAI protects both buyer and supplier. For the buyer, it confirms that the part matches the design. For the supplier, it confirms that the process is ready. In addition, FAI catches errors early. A wrong tool or a bad program shows up in the first part, not in the last one.
FAI also protects your schedule. If a problem appears during the run, you lose time and money. Therefore, we always run FAI before mass production. Moreover, the report serves as proof for your own customers. It shows that quality was verified, not assumed.
For regulated industries, FAI is mandatory. Aerospace suppliers follow AS9102. Medical and automotive projects use similar gates. In short, if your part is critical, your supplier should offer first article inspection as standard.
The cost of finding an error late is high. A bad batch means scrap, rework, and missed deadlines. In contrast, an FAI catches the error on one part. Therefore, the inspection pays for itself quickly. In addition, it protects the supplier’s reputation and your trust.
The AS9102 First Article Inspection Process
Aerospace uses the AS9102 standard for FAI. The process follows clear steps. Each step builds on the last one.
- Prepare the package. The supplier gathers the drawing, the bill of materials, and the requirements.
- Verify the material. The raw material certificate is checked against the drawing notes.
- Review the planning. The process plan lists operations, machines, and tools.
- Inspect all characteristics. Every dimension is measured with the right instrument.
- Record the results. Measured values, tolerance, and pass or fail status are documented.
- Complete the forms. AS9102 forms summarize part accountability, product accountability, and characteristics.
- Approve and file. The responsible engineer signs off, and the record is stored.
The standard also covers design accountability. The supplier must identify the drawing revision. In addition, it must list every characteristic that is verified. As a result, the first article inspection report is complete and repeatable.
The AS9102 forms also list supplier approval. Design engineering, quality, and manufacturing each sign their part. In addition, the forms capture any deviations from the drawing. Therefore, everyone knows what was approved and what was waived.
What a Complete FAI Report Contains
A professional first article inspection report is easy to read. It includes the drawing number and revision. It lists every characteristic with nominal value and tolerance. It shows the measured value and the result. In addition, it records the method and instrument for each check.
| Report section | What it shows | Why it matters |
|---|---|---|
| Part details | Drawing number, revision, material | Identifies the exact part verified |
| Characteristic list | Dimensions, tolerances, results | Proves every feature was measured |
| Measurement methods | CMM, gauge, caliper used | Shows how each number was obtained |
| Material certificate | Alloy, heat, traceability | Confirms the specified material |
| Sign-offs | Inspector, engineer, date | Documents accountability |
When a characteristic fails, the report shows the action taken. For example, the supplier may adjust the process and re-inspect. In addition, the report may include photographs of critical features. These details build trust and simplify your review.
Review the report with your own team. Confirm that every critical feature appears. In addition, check the instrument names against the requirements. A quick review at the start prevents problems at the end. Therefore, treat the report as a working document, not a formality.
When Do You Need First Article Inspection?
Request FAI for any new part. In addition, request it when the design changes. A new tool, a new material, or a new supplier also triggers a new inspection. In short, any change to the process deserves a fresh first article.
Repeat orders follow a simpler path. If the process is unchanged, the supplier can verify the last FAI. However, we still inspect key dimensions on every run. Therefore, our customers receive both first article depth and batch control.
Document the trigger points in your purchase order. For example, state that a new FAI is required for each revision. In addition, keep the reports with your part history. As a result, future orders start with proven records.
First Article Inspection FAQ
How long does an FAI take?
The time depends on part complexity. A simple bracket may take hours. A complex aerospace part may take days. In general, plan for one to three days on top of machining. In addition, we can provide a lead time estimate with your quote.
Do you provide first article inspection for prototypes?
Yes. Every new part receives a complete FAI at CNX Precision. In addition, prototypes get the same measurement depth as production parts. Therefore, you can validate your design before committing to volume.
What is the difference between FAI and a regular inspection?
A regular inspection samples key dimensions from a batch. An FAI checks every characteristic on the drawing. In addition, FAI verifies process planning and material. In short, first article inspection is the complete gate, while batch checks are the ongoing guard.
Conclusion
First article inspection is the foundation of machined part quality. It verifies the part, the process, and the records before production. As a result, it reduces risk for both sides. At CNX Precision, every new part receives a complete FAI with measured data. Send us your drawings today and request a full FAI with your quote.
For related information, see our guide to cnc machining service and 5-axis cnc machining and cnc milling vs turning and cnc machining tolerances.