When a European or US buyer sources machined parts from overseas, the parts themselves are only half the transaction. The other half is proof — the documents that show a part meets its drawing and that its material is what the drawing called for. If you’re buying from a new supplier, knowing which documents to ask for (and what each actually proves) is what separates a smooth first order from a quality dispute. Here’s a plain-English guide.

First Article Inspection (FAI)

An FAI is a full dimensional check of the first part off a new setup, before the rest of the batch is made. Every dimension and note on the drawing is measured and recorded against its tolerance. The point is to catch a programming or setup error on part one, not part one hundred. Ask for an FAI on a new part, a revised drawing, or any part where a mistake would be expensive. A good FAI report lists each feature, its nominal value, the tolerance, the measured actual and the deviation.

Dimensional / CMM reports

A CMM (coordinate measuring machine) measures a part in three dimensions against the CAD model or drawing, to a few microns. A CMM report is the evidence that critical features — bores, positions, profiles — are within tolerance. You don’t usually need every dimension CMM-measured on every part; the sensible approach is to agree the critical features up front and report those. When you read a CMM report, the columns that matter are nominal, actual, deviation and the tolerance band: a feature is fine when the deviation sits inside the band.

EN 10204 material certificates (2.1, 3.1, 3.2)

This European standard defines how a material’s properties are documented:

  • 2.1 — a statement of compliance from the supplier, with no test results.
  • 3.1 — a certificate with actual test results (chemical composition, mechanical properties) for the specific batch, validated by the mill’s inspection department. This is the one most industrial buyers ask for.
  • 3.2 — like 3.1 but countersigned by an independent inspector or the customer’s representative.

For most machined parts, a 3.1 certificate is the right level: it ties the material in your part to a real, tested batch. Ask for it at order stage, because it has to be sourced with the material — it can’t be created afterwards.

RoHS and REACH

For parts going into electronics or the EU market, buyers often ask for RoHS (restricted hazardous substances) and REACH (chemical registration) declarations. These usually come from the material and finishing suppliers; a machine shop passes them through.

The practical takeaway

Decide what you actually need before you order, and say so up front: which features get an FAI or CMM report, and whether you need a 3.1 material certificate. Documentation agreed at order stage is cheap; documentation demanded after delivery is a dispute. A supplier who asks you these questions early is one who understands export work.