Mill certs, heat lots and FAI: what to ask for before the quote
Documentation is where exotic alloy quotes quietly double. Not because anyone is padding, but because “Inconel 718” and “Inconel 718 with 3.1 certification, heat lot traced to the finished part, and AS9102 first article inspection” are two different products with two different process routes.
Decide which one you need before you send the RFQ, not after.
What each document actually proves
Certificate of Conformance (CoC). A statement from the supplier that the parts meet the drawing. It proves someone is willing to say so in writing. It proves nothing about the metal.
EN 10204 Type 2.2. A test report issued by the material producer, based on non-specific inspection — results from their routine production testing, not from your batch specifically.
EN 10204 Type 3.1. The important one for most work. The mill certifies the actual chemical composition and mechanical properties of the specific heat your material came from, validated by the mill’s own inspection department, which is independent of the production side. This is what people usually mean by “mill cert”.
EN 10204 Type 3.2. The same, but counter-signed by an independent inspector or your own representative. Required in some pressure, marine and nuclear contexts. Meaningfully more expensive and slower, because it involves scheduling a third party.
AS9102 First Article Inspection. Not a material document at all — a dimensional one. A structured report proving that the first part produced meets every characteristic on the drawing, with each feature ballooned, numbered and measured. Three forms: part number accountability, product accountability (including material and special processes), and characteristic accountability.
Those are different questions. A mill cert tells you the metal is what the drawing says. An FAI tells you the part is the shape the drawing says. Buyers sometimes ask for one while meaning the other.
The full FAI procedure, with its triggers and cost, is in AS9102 first article inspection.
Heat-lot traceability
A heat is one melt at the mill. Every bar from that melt shares a heat number, and the 3.1 certificate reports that heat’s chemistry and properties.
Traceability means the finished part can be tied back to its heat number — which requires the shop to segregate material physically, record which bar produced which parts, and mark or bag the parts accordingly. On a job running several bars across several weeks, that is real work, and it is why it belongs in the quote rather than in a phone call afterwards.
Ask for it explicitly if you need it. Ask for part marking with the heat number if you need that too; it is a separate operation.
What it costs
Rough guidance rather than a price list, because it scales with part complexity:
| Requirement | Typical impact |
|---|---|
| CoC only | Baseline |
| 3.1 mill cert | Small, if requested at RFQ stage |
| 3.1 plus heat-lot traceability to part | Noticeable on low volumes |
| Full dimensional report, all features | Can rival the machining cost on complex parts |
| AS9102 FAI | Significant one-off, then small per part |
| 3.2 with third-party witness | Significant, plus schedule risk |
The expensive combination is a complex part with many characteristics and a requirement to measure all of them on every piece. A part with sixty dimensions inspected 100 % is an inspection job with some machining attached.
Choosing the right level
Prototype, internal test, non-critical: CoC. Do not pay for more.
Production part, moderate consequence of failure: 3.1 mill cert, dimensional report on critical characteristics only, CoC on the rest.
Safety-critical, regulated, or customer-mandated: whatever the specification says, exactly. This is not the place to optimise.
The middle row is where most buyers can save money without taking on risk. Requiring 100 % inspection of every dimension when only four of them matter is common and expensive. Identify the critical characteristics on the drawing — mark them — and let the rest be sampled.
A note on certification claims
If a supplier’s quality system matters to you, ask for the certificate number and the certifying body, and check it. Certification registers are public. A shop that is genuinely certified will hand this over without hesitation.
We are a trading company rather than a manufacturer, so we hold no manufacturing certifications ourselves. What we do is audit the shop before an order is placed with it, check the mill certificate against the heat number before the first cut, inspect the parts against your drawing before packing, and ship the documentation your specification calls for with the parts on our own invoice.
The same logic applies one level up, to the shop’s quality system rather than the material — see AS9100 and what it actually tells you about a supplier.
Put it in the RFQ
One line in the RFQ prevents the whole problem:
Material: Inconel 718, solution treated and aged per AMS 5663. EN 10204 3.1 mill certificate required, heat lot traceable to finished parts. Dimensional report on characteristics marked CTQ. CoC on remaining features. No FAI required.
That is a quotable specification. “Inconel 718, aerospace quality” is not.
More on packaging the rest of the RFQ: why your hard-material RFQ sits unquoted. And on why identical drawings return different prices: why the same drawing comes back at three different prices.
Reference: EN 10204.
Send your drawing and your documentation requirements together — you will get one price that already includes both.