How FAI differs from sampling
An AQL inspection checks a few attributes on many units. FAI checks every characteristic on a few units, often just one. It belongs to engineering goods made to drawings: castings, forgings, machined parts, fasteners and assemblies. In aerospace, SAE AS9102 sets the requirement and the forms for recording it. Automotive buyers use a related approval route, PPAP, which includes dimensional results on production parts. Consumer goods use the simpler idea of comparing first units with a golden sample, sometimes called an initial production check.
Worked example: a brass valve body
A buyer orders 10,000 CNC-turned brass valve bodies. The drawing carries 34 numbered characteristics: diameters, lengths, two threads, a surface finish note, the alloy and a plating requirement.
- The factory makes the first pieces on the production machine, with production tools and program.
- Each of the 34 balloons is measured and recorded with the instrument used and the result.
- Material and plating are checked against certificates, such as an EN 10204 3.1 certificate.
- The report shows that balloon 17, a port thread, was cut to NPT where the drawing called for BSP. The program is corrected and the affected characteristic is measured again before the run is released.
Found later, the same error would have affected the whole lot.
How Clear To Load supports FAI
In a pre-production inspection we check first-off parts, material certificates and tooling against your drawing, using hand gauges and the factory's calibrated equipment, including a CMM where it has one, while we watch. We report differences for your engineers to decide. We do not sign off an AS9102 FAI or approve a PPAP; that approval belongs to your organisation. Tolerances not stated on the drawing usually fall back to a general tolerance standard such as ISO 2768, if the drawing names it.