Technical Deep-Dive 05
"How Will You Prove the Finished Geometry — Can I Get a Report?"
CMM Verification, FAI Reports and Documentation for Complex 5-Axis Parts
Contoured multi-axis parts cannot be validated with callipers and micrometers alone. Surface profile, cross-face position and blade geometry require coordinate measurement referenced to your datum scheme. This page explains exactly what we measure, how we measure it, what documentation you receive, and how to specify inspection requirements that match your application's risk level.
The Short Answer
We provide multiple levels of inspection documentation depending on your requirements:
- CMM point measurement or scanning against your datum scheme (not against a convenient shop reference) — this is our baseline for all complex 5-axis work.
- First Article Inspection (FAI) report on request — standard practice for new part numbers; verifies every drawing characteristic before batch release.
- Full dimensional report against a ballooned drawing — available for any part where you need complete traceability.
- Material and surface-treatment certificates including mill test reports (MTRs), heat treatment records, and coating/plating certifications where applicable.
- Custom measurement-point programs — supply your balloon drawing or point list and we will measure to your specification.
What We Measure and How
Different feature types require different measurement methods. The table below maps each feature category to the method we use, the typical output format, and when each is applied.
| Feature Type | Measurement Method | Typical Output | When Applied |
|---|---|---|---|
| Complex surface profile (impeller blades, contoured housings, mould cavities) | CMM point measurement or scanning vs CAD nominal surface | Deviation report (point-by-point or colour-map); max deviation; profile tolerance pass/fail | All simultaneous 5-axis contoured parts; standard for FAI |
| Blade / vane contour | CMM scanning or dense-point measurement at defined sections | Profile deviation per section; leading/trailing edge analysis; thickness map | Impeller, turbine-blade and compressor-wheel components |
| Hole position across faces | CMM with datum alignment to drawing's A-B-C reference frame | True-position report per GD&T callout; deviation from nominal position; MMC bonus if applicable | Multi-face parts with cross-face positional tolerances |
| Bore diameter and form | CMM bore circle measurement or dedicated bore gauge | Diameter; roundness; cylindricity (if specified); taper check | All precision bores; bearing journals; sealing interfaces |
| Runout / concentricity | CMM radial deviation scan or indicator setup on rotary axis | Total indicated runout (TIR); concentricity value; graphical polar plot | Rotational features: shafts, hubs, flanges, bearing seats |
| Surface roughness Ra / Rz | Profilometer (contact stylus) or optical surface-measurement system | Ra value per specified area/feature; Rz if requested; traceability to instrument calibration | Where surface finish is specified on drawing (sealing faces, flow surfaces, cosmetic areas) |
| Threaded ports | Thread go/no-go gauges + CMM positional inspection of thread axis | Go/no-go result; thread-axis position relative to datum; depth verification | All threaded features where both form and position are critical |
| Thin-wall thickness | Ultrasonic thickness gauge or CMM dual-surface probing | Thickness map at defined points; min/max thickness; variation across part | Thin-wall structures (nominal wall <2 mm); lightweight aerospace-style components |
| Flatness / perpendicularity / parallelism | <CMM plane measurement with datum reference | Tolerance zone value; deviation from ideal plane/axis; graphical deviation map | Sealing faces; mounting surfaces; assembly interfaces |
Documentation Package: What You Can Request
Standard Documentation (Included)
- Dimensional inspection report with key characteristics measured
- CMM output referenced to customer datum scheme (A-B-C sequence as drawn)
- Material certificate (mill test report) confirming alloy grade and heat number
- Surface-treatment certificate where applicable (anodizing, plating, passivation record)
- Final outgoing quality confirmation before shipment
Premium Documentation (Available on Request)
- First Article Inspection (FAI) report — full AS9102-style or equivalent ballooned-drawing verification of every characteristic
- Full dimensional report against customer-supplied balloon drawing with all dimensions reported
- CMM scanning data (point cloud or colour-map deviation file) for contoured surfaces
- Customer-specified measurement points — supply your point list or balloon drawing and we measure to it
- 100% critical-dimension inspection — defined sampling plan or 100% check on flagged features (quoted separately)
- SPC trend data for production runs (Cpk analysis on key characteristics over batch)
When to specify premium documentation during RFQ: if your application requires formal quality records (aerospace, medical device, automotive PPAP, regulated industry), tell us at quotation stage. Adding FAI or 100% CMM requirements after the quote is accepted will affect lead time and cost — it is always more efficient to plan inspection into the process from the start.
Why Datum Alignment Matters More Than Instrument Accuracy
The most common cause of inspection disagreement between supplier and customer is not CMM accuracy — it is datum establishment methodology. Both parties may have perfectly calibrated CMM machines that produce different results because they are measuring from different reference frames.
The Problem Scenario
Your drawing defines datum A as a bore axis, datum B as a perpendicular face, and datum C as a slot. The supplier's CMM report shows all dimensions in spec. Your incoming CMM shows three holes out of position by 0.018 mm. Both CMMs are calibrated. Who is right?
Most likely answer: both instruments measured correctly, but the supplier's CMM established datums from the largest flat face (convenient for resting the part), while your CMM followed the drawing's A-B-C bore-face-slot sequence. The results are not comparable because they are measuring different things.
How to Prevent It
- Require datum sequence in the RFQ: explicitly state that CMM output must be referenced to the drawing's A-B-C datum precedence order
- Ask for the CMM program datum setup: any reputable supplier can provide the datum-establishment sequence used for their report
- Supply a balloon drawing: numbered characteristics with datum callouts eliminate ambiguity about which reference to use for each measurement
- Watch for pattern vs scatter: if all parts shift in the same direction, it is likely a datum offset; if non-conformances are scattered randomly, it may be fixture repeatability or thermal drift
What Goldcattle Does Differently
- Our CMM reports state the datum establishment sequence used for each measurement
- Default alignment follows the drawing's GD&T datum precedence (A→B→C), not the most convenient clamping face
- If the drawing has ambiguous or missing datums, we propose a scheme and include it in the DFM feedback before cutting
- For contoured surfaces, we report deviation relative to CAD nominal in the customer's datum frame, not in an arbitrary machine coordinate system
Our Quality Certifications and Traceability System
ISO 9001:2015
Quality management system covering design control, process validation, document control and continuous improvement
SGS Certification
SZIN2409001808ML09_EN — third-party verified quality management compliance
RoHS Compliance
TQT7737B1373EC — restricted substances compliance for materials supplied to EU markets
National High-Tech Enterprise
26 years of in-house precision manufacturing experience with audited quality systems
100+ Countries Served
Component delivery experience across EU, North America, Southeast Asia and global markets
Frequently Asked Questions
Do you provide First Article Inspection (FAI) reports?
Yes, on request. FAI is standard practice for new part numbers and is included in our premium documentation package. The FAI report follows AS9102 or equivalent structure: Part Accountability (Form 1), Product Accountability (Form 2 with material and process certs), and Dimensional Characteristic Accountability (Form 3 with every drawing characteristic measured and reported). If your organisation uses a specific FAI template (AS9102, PPAP Level 3, or internal format), supply it and we will report to its structure.
Point measurement or scanning — which do you use by default?
Point measurement is our default for prismatic features (bores, holes, flat surfaces, linear dimensions). Scanning is used where continuous profile evaluation is specified (contoured surfaces, blade profiles, mould cavities) or where the customer requests it. Scanning provides richer deviation data but takes longer and costs more than point measurement. If you are unsure which your part needs, we will recommend based on geometry and tolerance requirements.
Can I specify my own measurement points?
Yes. Supply a balloon drawing (numbered drawing with each characteristic assigned an ID) or a point-coordinate list, and we will measure and report against those specific points. This is particularly valuable for applications where certain dimensions are safety-critical or assembly-sensitive and need guaranteed coverage regardless of the supplier's default inspection plan.
Is inspection documentation included in the quoted price?
Basic dimensional reporting (key characteristics measured, material cert provided) is included in our standard pricing. Full FAI reports, custom CMM programmes, 100% critical-dimension inspection schemes, and SPC trend reporting are quoted separately and transparently — they are visible line items in the quotation so you can decide what level of documentation your application requires. Our recommendation: specify documentation requirements during RFQ so they can be planned into the process from the start.
What CMM equipment do you use?
We use coordinate measuring machines with sub-micron positioning accuracy, equipped with touch-trigger probe systems and capable of both point measurement and scanning operations. All measurement equipment carries current calibration certificates traceable to national standards. Specific make/model details and calibration certificates are available during supplier audit or on request.
Need Specific Inspection Documentation for Your Application?
Tell us your industry (aerospace, medical, automotive, industrial automation) and documentation standard (AS9102, PPAP, ISO 13485, or internal). We will match our inspection and reporting package to your requirement and quote it transparently.
All CMM reports include datum-sequence documentation. Calibration certificates available on request.
