Understanding First Article Inspection (FAI) in CNC Machining

All About First Article Inspection (FAI)

First Article Inspection (FAI) in CNC Machining

In precision manufacturing, quality and consistency in machined parts are essential. First Article Inspection (FAI) is one of the most significant quality control processes applied in CNC machining. It serves as a crucial process to ensure that a manufactured part complies with all approved engineering and design specifications prior to the start of full-scale production. At PMP Metals, where we specialize in high-precision CNC machining and metal fabrication, FAI is the cornerstone of our quality control process.

The article below will discuss everything you need to know about FAI, including its application, process, benefits, and how it is applied in today’s CNC machining.

What is First Article Inspection (FAI)?

First Article Inspection (FAI) is a formal, written process that ensures the manufacturing of a part or assembly meets the customer-defined or engineering-defined design specifications, drawings, and requirements. FAI is typically performed on the first part produced in a production run or after significant changes in the manufacturing process.
The procedure involves careful measurement, inspection, and comparison of physical characteristics such as:

Dimensions
Geometric tolerances
Surface finish
Material properties
Thread types and hole sizes
Functional testing results (if carried out)

The results are documented in a detailed First Article Inspection Report (FAIR) which lists the measured values against the standard tolerances.

Why is FAI Critical in CNC Machining?

CNC machining involves the production of parts with accurate tolerances and precise specifications. An error in a single parameter will cause part failure, recall at a high cost, and downtime. FAI is therefore critical in CNC machining because:

Process Accuracy Verification: FAI validates that the fixturing, tooling, setup, and CNC program are producing parts to the customer’s specifications. It helps verify the correctness of every stage of the production process.
Reduced Scrap and Rework: Early identification of problems eliminates waste, rework, and time wasted on troubleshooting in subsequent stages of manufacturing.
Customer Confidence: For OEMs and customers in industries such as aerospace, defence, medical, and automotive, FAI ensures that a supplier such as PMP Metals can deliver parts consistently to stringent standards.
Traceability and Compliance: FAI facilitates traceability and industry standard compliance like AS9102 (used extensively in the aerospace industry). It also facilitates compliance with ISO 9001 and IATF 16949 compliance.

When is First Article Inspection Necessary?

FAI is not performed on every part, but is necessary under the following circumstances:

First Production Run: Part being manufactured for the first time.
Engineering Changes: Design, material, or tolerance alteration.
Manufacturing Location or Equipment Change: If the part is being produced now on different equipment or in another facility.
Process or Suppliers Change: New tooling, different materials, or a new supplier could necessitate FAI.
After a Production Gap: If the part has never been made for over a very long time (typically 2 years), a new FAI may be necessary.

The First Article Inspection Process: Step by Step

FAI involves a series of standard steps and documentation. With PMP Metals, we have an extensive and definitive process to ensure quality:

Engineering Documentation Review: Before anything is machined, the specifications and engineering drawings are reviewed for completeness and accuracy. Material calls, GD&T specifications, and revision levels are reviewed.
First Article CNC Machining: The first article part is manufactured with the ultimate production setup, tooling, CNC program, and work instructions. This will reveal true production capability in the output.
Dimensional Inspection: This is the most critical part of FAI. Each measurement on the drawing is taken with accuracy checking equipment such as:
- Callipers and micrometres
- Coordinate Measuring Machines (CMM)
- Optical comparators
- Height gauges
- Surface finish testers
Measured values are compared to tolerances on the drawing and documented in the FAIR.
Material and Certification Review: Material certifications, heat treat certifications, and the reports of any plating or coating are collected and reviewed to ensure the correct raw material and process were used.
Functional Testing (As Required): Functional tests such as pressure, electrical, or thermal testing can be required on some components to ensure they function properly.
First Article Inspection Report (FAIR) Compilation: The results are compiled into a FAIR which includes: • Part drawing with numbered characteristics (ballooned drawing) • Dimensional outcome table • Certifications for the material • Machine and tooling information • Signatures of the operator and inspector • Non-conformance reports, if any
Acceptance or Rejection: The FAIR is reviewed internally and then dispatched to the customer for approval. Once everything is by specification, the part is approved for mass production. In the event of defects, the corrective action is taken, and a new FAI is performed.

Tools and Technology Used in FAI

Modern FAI processes are supported immensely by advanced inspection and measurement tools:

CMM (Coordinate Measuring Machines): Automatic measurement of complex geometries.
Vision Systems and Optical Comparators: Non-contact measurement for complex or fragile parts.
3D Scanning: For complex shapes and reverse engineering.
Digital FAIR Software: Software like Net-Inspect or QIF-based software makes reporting, traceability, and revisions easier.

At PMP Metals, we employ a blend of traditional tools and state-of-the-art digital inspection systems to deliver accuracy and repeatability.

FAI and Industry Standards

FAI is not only a best practice in most industries—it’s a requirement. The following are some of the standards that govern FAI:

AS9102 Standard

Used primarily in aerospace and defence, AS9102 defines the format and content of FAIRs. It requires documentation of:

Form 1: Part number accountability
Form 2: Product responsibility (material, processes, functional tests)
Form 3: Characteristic responsibility (dimension and tolerances) ISO 9001 and IATF 16949

These international quality standards recommend FAI as part of a comprehensive quality management system. PMP Metals adheres to all industry and customer-specific relevant standards to ensure compliance and excellence.

Common Challenges in FAI and How They Are Overcome

FAI, although important, is not immune to challenges:

Time-Consuming Process: Taking a complete FAI is time-consuming. Mitigation: Employ computerized tools to automate analysis and data input and conduct the FAI during low-production times.
Errors of Interpretation: Misreading tolerances or dimensions can result in inaccurate reporting. Mitigation: Train inspectors and utilize well-balanced drawings.
Incomplete Documentation: Lacking material certs or process documentation can hold up approvals. Mitigation: Utilize standard checklists for thoroughness.
Resistance from Production Teams: Others see FAI as a bottleneck. Mitigation: Emphasize how FAI prevents rework and builds customer trust.

Advantages of a Successful FAI Program

Having an effective FAI program in place offers some long-term advantages:

Reduces the risk of nonconforming products
Increases customer satisfaction and trust
Improves internal processes and training
Reduces costs associated with scrap, rework, and returns
Enables better process control and capability analysis

At PMP Metals, our FAI procedures are part of a larger lean manufacturing, Six Sigma philosophy, and continuous improvement pledge.

The Future of FAI in Manufacturing

As CNC machining becomes increasingly automated and integrated with Industry 4.0, FAI is also evolving:

Real-Time Data Collection: Sensors and IoT devices can feed real-time data to FAI systems.
AI-Driven Inspection: Machine learning can predict quality problems and warn us before they occur.
Digital Twins: Virtual production environments allow for virtual FAIs before physical parts are produced.

PMP Metals is investing in these technologies to improve our inspection and quality control processes.

Conclusion

First Article Inspection is more than a quality control step—it’s a foundation of accuracy, repeatability, and confidence in CNC machining. By verifying the first part of the line meets every requirement, FAI reduces risk, builds customer confidence, and clears the way for repeatable, trouble-free production.

At PMP Metals, we understand that precision is important. Our careful attention to FAI ensures not only that each part we machine fits your exact specifications, but also that it meets our own high level of excellence, reliability, and innovation. Whether you’re producing parts for aerospace, medical, automotive, or industrial use, you can count on PMP Metals to deliver with quality, openness, and precision—from the very first article.

Ready to partner with a precision CNC machining company focused on quality? Contact PMP Metals today to learn more about our FAI processes and how we can help with your next project.