âš¡ Direct Answer: What Is on a Sheet Metal Enclosure First Article Inspection (FAI) Checklist?
A rigorous sheet metal enclosure First Article Inspection (FAI) checklist audits 5 critical verification categories before mass production release: 1) Enclosure Dimensional & Squareness Verification: Measuring overall height, width, depth, and diagonal squareness difference (<0.8mm diagonal delta) on CMM surface plates; 2) Seamless Formed-in-Place Foam Gasket (FIPFG) Integrity: Verifying polyurethane gasket width, height, and uniform 25%–35% compression without voids or joint seams; 3) Door Hinge & Multi-Point Latch Operation: Testing 130°–180° swing freedom, cam latch compression force, and door sag (<0.5mm); 4) Powder Coating Film Quality: Measuring dry film thickness (DFT 60–90µm), ASTM D3359 cross-hatch adhesion (Class 4B/5B), and solvent resistance; and 5) Sub-Plate & DIN Rail Fit-Up: Validating mounting stud centers and electrical ground continuity (<0.010 ohms).
Sheet Metal Enclosure FAI Inspection Protocol
| Inspection Parameter | Inspection Tool / Standard | Acceptance Criteria | Documentation Deliverable |
|---|---|---|---|
| 1. Diagonal Squareness | Laser tracker / Vernier calipers | Corner-to-corner diagonal difference <0.8mm | CMM coordinate measurement report |
| 2. Gasket Profile & Seal | Optical profile gauge / feeler strip | Uniform height ±0.2mm; continuous FIPFG seal | PU dispensing program log & photos |
| 3. Coating Thickness (DFT) | Magnetic induction gauge (ASTM D7091) | 60µm to 90µm average across 10 sample points | Coating thickness inspection certificate |
| 4. Paint Adhesion | Cross-hatch tape test (ASTM D3359) | Class 4B or 5B; zero flaking at grid intersections | Destructive test coupon photo log |
| 5. Grounding Path Continuity | Milliohm meter (four-wire Kelvin method) | Resistance R < 0.010 ohms between door & body | Electrical continuity sign-off sheet |
A sheet metal enclosure is an active protection system housing sensitive power drives, PLCs, and safety relays. When importing enclosures from overseas, an ambiguous “parts approved” email creates catastrophic risk. A formal First Article Inspection (FAI) report provides hard mathematical verification that door hinges will not bind, gaskets will compress evenly to guarantee IP66/NEMA 4X ingress protection, and grounding paths conform to UL 508A requirements.
CMM Dimensional Verification, PU Gasketing & Powder Quality
At MSTFAB, every FAI enclosure undergoes complete dimensional probing on a coordinate measuring machine (CMM) to map datum coordinates against the customer’s 2D ballooned drawing. Our CNC robotic polyurethane dispensing head applies seamless liquid foam gaskets directly onto door channels, creating a continuous water barrier without corner cuts or joints.
Require Complete FAI Documentation for Custom Enclosures?
Partner with MSTFAB for custom electrical and industrial enclosures with complete AS9102-style FAI dossiers, CMM reports, and material mill test certificates.
Frequently Asked Questions on Enclosure FAI Checklists
How is door sag measured during an enclosure FAI?
A dial indicator is mounted to the enclosure frame touching the top corner of the latch edge. The door is opened 90° and closed; vertical displacement must not exceed 0.5mm to ensure latch cam engagement without binding.
What testing verifies that the enclosure meets IP66 water ingress ratings?
We conduct internal spray testing per IEC 60529 (100 L/min water jet at 100 kPa from 2.5m distance for 3 minutes) against sample enclosures, followed by internal inspection for any water ingress.
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