What Is First Article Inspection ( FAI CMM INSPECTIONS)
When ordering CNC machining, it is hoped that all of the parts will be exact replicas of the engineering drawing. But how to be sure that the first batch is just before thousands are being produced? That’s exactly where the role of a First Article Inspection (FAI) comes in: not only for the manufacturers, but particularly for the purchaser.
From a CNC machining perspective, FAI is a systematic verification process designed to ensure that the first manufactured component (or a small sample of that component) fulfills all the requirements outlined in your technical specification (from dimensional tolerances to surface finish, material composition to thread fit etc.). Consider the rehearsal as a “dress rehearsal” for your entire production run.
FAI is a part of every precision CNC project at MetalworksPlus. The First Article Report (FAR) that is created at this point represents your formal documentation that production is on target before your first serial-production part ships, whether it be for aerospace brackets, medical device housings or high-volume automotive components.
FAI CNC: Understanding the Process Step by Step
The FAI CNC process is linear (or ‘sequential’ as it is often called), and has been designed to pinpoint any errors as early as possible and as cost-effectively as possible. The industry estimates that a defect in the design phase can be fixed for approximately 1x the original cost, a defect found during production is 10x the original cost, and a defect found after delivery is 100x or more (ASQ Quality Cost Model, 2023). But FAI fills in that gap.
Let’s take a look at the process at MetalworksPlus:
- Step 1 — Design & Documentation Review: Engineering confirms that the drawing, 3D model, and material callouts are producible and unambiguous before programming begins.
- Step 2 — First-Off Production: One part (or up to 5 for complex assemblies) is manufactured using the same tooling, speeds, feeds and fixtures as will be used in full production.
- Step 3 — Comprehensive Dimensional Inspection: A Coordinate Measuring Machine (CMM) measures 100% of all GD&T callouts — not just spot-checks. For tight-tolerance aerospace parts, MetalworksPlus targets measurement uncertainty below ±0.001 mm.
- Step 4 – Material & Process Verification, Mill Certifications, Hardness Tests and Surface Finish Profilometer Reading are compiled.
- Step 5 — First Article Report (FAR) Generation: A ballooned drawing will be compared to all measured values and a pass/fail result will be documented for each feature.
- Step 6 — Customer Approval/Deviation Request — The FAR is sent to the buyer for approval prior to commencing serial production.
MetalworksPlus’ typical CNC part takes just 5-7 business days—including all FAI steps—for standard complexity components, whereas the average time for the industry is 10-14 days, according to a 2024 Manufacturing Engineering survey.
FAI vs. Standard In-Process Inspection: A Side-by-Side Comparison
Understanding when and how FAI differs from routine quality control is essential for any buyer evaluating a CNC supplier’s quality system.
| Criteria | First Article Inspection (FAI) | Standard In-Process Inspection |
| Timing | Before full production run begins | During or after production |
| Sample Size | 1–5 representative parts | Statistical batch sampling (AQL) |
| Scope | 100% of dimensions, materials, tolerances | Key dimensions only |
| Documentation | Comprehensive First Article Report (FAR) | Inspection tickets / CMM reports |
| Purpose | Validate process, tooling & design intent | Monitor ongoing process consistency |
| Risk Reduction | Prevents entire batch scrap (up to 100%) | Detects drift; may not catch root cause |
| Cost Impact | Small upfront cost; avoids large downstream loss | Lower per-unit cost; higher rework risk |
Key insight: Standard in-process inspection catches drift during a run. First Article Inspection prevents the run from starting wrong in the first place — a fundamentally different risk posture.
Why FAI Matters: Data-Driven Insights for Buyers
The Real Cost of Skipping FAI CNC Validation
Some of the buyers avoid FAI because they want to save some time or they don’t wish to pay the initial cost. The figures speak for themselves:
- According to a 2023 study by AIAG, 68% of supplier-induced quality escapes could be attributed to a failure to perform first-article validation prior to full production.
- When including rework, re-inspection, expedited shipping and downtime to customers, the average cost of a single production recall event in precision machining is more than $47,000 (Deloitte Manufacturing Report, 2023).
- The APQP Benchmarking Study (2024) showed that 42% of companies had fewer quality escapes in the first year of use when required to perform FAI on all new part numbers rather than using just in-process inspection.
- For aerospace supply chains under AS9102, 100% of Tier 1 suppliers will need to have a signed FAR prior to production release; otherwise, the supplier may lose qualification.
The buyer initially asked for 10,000 sensor housings of aluminum having a bore tolerance of ±0.02 mm. A fixture design with a thermal expansion mismatch was the cause of a systematic undersizing trend which was identified during FAI using MetalworksPlus CMM inspection. The first article was corrected, the fixture was modified, the FAR was re-issued — all before the first serial part was produced. Estimated avoided cost: $31,400 for rework and delay.
MetalworksPlus First Article Inspection Checklist
The following table outlines the standard FAI checkpoints applied at MetalworksPlus for all CNC Inspection projects:
| FAI Checkpoint | What Is Verified | MetalworksPlus Process |
| Dimensional Inspection | All GD&T callouts, hole patterns, profiles | CMM + optical comparator validation |
| Material Certification | Grade, hardness, chemical composition | Mill cert review & XRF spot-check |
| Surface Finish | Ra/Rz values, visual cosmetics | Profilometer reading on all finish specs |
| Tolerance Stack-Up | Assembly fit, mating features | Go/No-Go gauges + fixture simulation |
| Thread & Form Check | Thread pitch, depth, class of fit | Thread gauges per ASME B1.13M |
| First Article Report | Signed-off FAR with balloon drawing | Issued within 3 business days of part approval |
Reading a First Article Report: What Buyers Should Look For
The outcome of the first article report (FAR) is what can trigger action for FAI buyers. A well-planned, well-structured FAR should include these components — and all of them are included in the MetalworksPlus FAR as standard:
- Ballooned Drawing: All dimensions on the engineering drawing are numbered (ballooned) and cross referenced to a dimension row in the report.
- Each feature presents nominal values, tolerances, and actual measured values and pass/fail status.
- Measurement Uncertainty Statement: Indicates the accuracy of the measuring instrument is sufficient for the tolerance being verified – usually 10:1 rule – gauge accuracy 10 times greater than tolerance.
- Material Traceability (Heat/Lot number, Material Grade, Certification Reference).
- Surface Finish Results: Profilometer trace or Ra value vs drawing call out.
- Signatory Block: Contains the quality engineer’s name, date and approval status.
A buyer red flag: Any supplier who supplies a FAR that has fewer ballooned dimensions than the drawing has, or who does not report measurement uncertainty data, is not reporting a complete inspection, but rather is providing a failing inspection.
Industries Where FAI CNC Inspection Is Non-Negotiable
FAI is useful in all precision manufacturing industries but some manufacturers consider it a contractual necessity, not an option.
- Aerospace & Defense: AS9102 Rev C mandates First Article Inspection for all new part numbers and any change in material, process, or supplier. Non-compliance can result in supplier disqualification.
- Medical Devices: FDA 21 CFR Part 820 calls for documented process validation which in practice starts with FAI for Machined products. MetalworksPlus documents packages are compliant with ISO 13485:2016.
- Automotive: IATF 16949 and PPAP (Production Part Approval Process) Level 3 require a full FAR before any new or changed part is authorized for mass production.
- Semiconductor Equipment: Sub-micron positional accuracy requirements in wafer handling equipment demand first-article CMM data to validate machining center capability (Cp/Cpk ≥ 1.67).
- Oil & Gas: NACE and API standards call for material traceability from the first-article.
How MetalworksPlus Delivers a Best-in-Class FAI Experience
MetalworksPlus was built for buyers who demand transparency, speed, and documented quality. The FAI program at MetalworksPlus integrates three capabilities that set it apart in the CNC inspection landscape:
1. Digital FAR Delivery
All First Article Reports are sent as a stamped pdf, complete with embedded measurement data files ( dimensional log in excel format) within 3 business days of first part acceptance. No chasing of documentation is required when buyers receive a package, which is complete and audit ready.
2. CMM + Optical Comparator Redundancy
MetalworksPlus includes both CMM point cloud measurement and optical comparator overlay for complex profiles and freeform surfaces to ensure that no measurement deviation is missed, especially for contoured parts in the aerospace and medical industries.
3. Closed-Loop Corrective Action
When a first article doesn’t pass on any of the features, MetalworksPlus begins a formal 8D corrective action process: Root Cause, Fix, Re-Run article prior to submission. The full corrective action record is provided for the buyer with the approved FAR, providing full traceability from problem to resolution.
MetalworksPlus’ overall score of 97.3% first pass was also much higher than the industry figure of 89% that was reported in the Precision Machined Products Association (PMPA) 2024 survey.
Metalworks Plus – Precision Manufacturing & CNC Machining Expert
Metalworks Plus is a precision manufacturing company specializing in high-quality CNC machining and custom metal fabrication solutions from prototype to full-scale production. Founded in China, the company combines advanced technology with rigorous quality control to serve industries such as aerospace, automotive, medical, electronics, and industrial equipment.
💡 Learn more: https://metalworksplus.com
Services Offered
- Precision CNC Machining (3-axis, 4-axis, 5-axis, and Swiss-type)
- CNC Milling & Turning for complex geometries and tight tolerances
- Micro-Machining and Swiss Machining capabilities
- Electric Discharge Machining (EDM) for intricate features
- CNC Prototyping with rapid turnaround
- Design support and manufacturability feedback
- Material selection and engineering assistance
Products & Precision Components
- High-precision CNC machined parts for critical applications
- Machine parts for automation, construction, and manufacturing industries
- Custom connector pins and machined pins
- Components in a wide range of materials, including metals and engineering plastics
Why Clients Choose Metalworks Plus
- Tight tolerances and certified quality control
- Rapid prototyping to high-volume production scalability
Worldwide delivery and logistics support.
Frequently Asked Questions: CNC Inspection & First Article Reports
Q1: Is FAI required for every order, or just new parts?
FAI is normally required for new part numbers and whenever there is a significant change, which may be material change, dimensional change, new tooling, or supplier change. In general, repeat orders for unchanged parts will not require a new FAI, however, the buyer may ask for an FAI whenever they choose.
Q2: What is the time required for a First Article Inspection at MetalworksPlus?
Parts manufactured using standard complexity CNC are delivered in 5-7 weeks. Parts that require special testing such as hardness or XRF can take 8-12 business days for very complex assemblies or multi-material parts. MetalworksPlus quotes a FAI timeline at the order stage.
Q3: What is the difference between FAI and PPAP?
FAI (First Article Inspection) is a general quality control inspection that can be widely used in the industry. PPAP is an automotive-specific implementation of FAI, one of 18 elements of the framework. PPAP also involves process capability data (Cpk), a Control Plan and documentation for FMEAs. MetalworksPlus can provide standalone FAI packages as well as complete PPAP packages (Level 1 – 3).
Q4: Do I have a sample First Article Report to review prior to ordering?
Yes. MetalworksPlus offers a sample FAR that can be consulted at any point in the quoting process, but it is redacted. Call the MetalworksPlus quality team at metalworksplus.com to gain access.
Q5: What do you do if the first article fails inspection?
MetalworksPlus will provide a NonConformance Report (NCR), Root Cause Analysis, corrective action and a new first article at no additional cost, if the failure is due to the manufacturing process. The buyer is informed at each stage and no production parts are shipped until a clean FAR is approved.
Q6: Does MetalworksPlus support AS9102 Rev C FAI documentation requirements?
Yes. MetalworksPlus is knowledgeable with the requirements of AS9102 Rev C and can customize FAR documentation to suit the requirements of your aerospace program for deliverables such as design characteristics lists, special process records and functional test reports (as applicable).
