How to Read an Aluminum Coil Mill Test Certificate.

A mill test certificate is the paper that lets a buyer compare the coil on the dock with the coil on the purchase order (PO). Reading it takes a few minutes once you know which line to check against which document.

Key takeaways

  • A certificate records what was supplied. The purchase order and the standard it names record what was required. Reading the certificate means comparing the two.
  • Check in order: alloy and temper, chemistry, mechanical properties, dimensions, then the lot reference that ties the paper to the coil.
  • ASTM B209 is the specification for aluminum sheet and plate, including coiled sheet. The EN 485 series and EN 573-3 are the European reference points, and EN 10204 defines the types of inspection document.
  • A certificate that does not name the standard and the temper it was tested against is harder to check than one that does.
  • At Orbit, material certificates accompany every batch. Test reports and ASTM or EN references are available on request, and coil is tagged with lot and specification details.

What is a mill test certificate, and what is it for?

It is the supplier's record of what was delivered. A certificate reports test and inspection results for the material supplied and refers to the specification that material was supplied against. The name varies (mill test certificate, material certificate, inspection certificate) and so does the layout, so this guide covers what to check rather than one fixed format.

In Europe, the types of inspection document are defined in EN 10204, which applies to metallic products generally and separates documents based on non-specific inspection from documents based on specific inspection. The certificate is evidence about one lot. It means something only when it is read against what you ordered.

In general terms, type 2.2 states compliance with the order and reports test results from non-specific inspection, and type 3.1 is based on specific inspection of the lot supplied. State on the PO which type you require.

Which standard should the certificate reference?

For coil ordered to a US specification, the reference is ASTM B209/B209M, the specification for aluminum and aluminum-alloy sheet and plate. It covers flat sheet, coiled sheet and plate in the alloys and tempers listed in its tables.

For European delivery, EN 485-1 sets the technical conditions for inspection and delivery, EN 485-2 covers mechanical properties, EN 485-4 covers tolerances on shape and dimensions for cold-rolled products, and EN 573-3 covers chemical composition. Put the standard on the purchase order and expect the certificate to name the same one. If the order cites ASTM B209 and the certificate cites an EN standard, settle the difference before the coil is processed.

How do I check the alloy, temper and chemistry?

Start with the alloy designation and the temper, and compare them with the order character for character. A 3105 coil is not a 3003 coil, and an H-series temper is not an O temper. Then find the chemical composition block, where results are listed element by element, and compare each result with the composition limits for the alloy named.

Those limits are registered by the Aluminum Association and, for European delivery, published in EN 573-3. The check is whether each reported value falls inside the limit for that alloy, not whether the value looks reasonable on its own. For why temper belongs on every line item, see the alloy and temper guide.

What do the mechanical property lines tell me?

Tensile strength, yield strength and elongation are test results for the alloy and temper supplied. On a document based on specific inspection they come from testing of the lot supplied, and other document types may report non-specific results. Compare each one with the requirement for that alloy, temper and thickness in the standard the order cites. ASTM B209 publishes its requirements in tables organized by alloy and temper, and EN 485-2 plays the same role in Europe.

A result inside the requirement means that property conforms. The lot conforms only if every PO requirement is met: dimensions, tolerances, the other properties and the inspection document type. A result sitting close to a limit leaves little margin, so look again at temper and gauge before the coil goes onto a demanding forming operation. Check the units as well, since strength can be reported in megapascals or in ksi, and read the value against the right column of the standard.

Do dimensions and flatness need to match as well?

Yes. Thickness and width on the certificate should match the order, and the tolerances should be the ones the order specified. Tolerance tables sit in the dimensional standard the order cites, and EN 485-4 is the European reference for cold-rolled products.

The certificate reports what was measured on the lot. It does not replace checking the coil you receive, so measure thickness and width on a sample at receiving and compare them with the order. For coated coil the order also names the coating system, color and finish, so check those against the order too.

How does the certificate connect to the coil in front of me?

Through the lot reference. The certificate carries a lot or coil reference, and the coil carries a tag with the same reference. Read the tag, read the certificate and confirm they match. When several coils arrive on one order, check each coil's tag against its own entry. That link is what makes a later problem traceable to a lot.

  • Alloy and temper on the certificate match the order
  • Standard named on the certificate matches the order
  • Chemistry and mechanical results sit inside the limits
  • Thickness and width match the order and its tolerances
  • Lot reference on the certificate matches the tag on each coil

What should I do if the paper and the coil disagree?

Hold the coil. Do not slit, coat or run it until the difference is settled. Photograph the tag, note the lot reference, and send the certificate and the purchase order to the supplier with a clear statement of which line differs.

If a certificate is missing or unreadable, ask for a copy before the coil is used.

What documentation does Orbit provide?

Material certificates accompany every batch. Test reports and ASTM or EN references are available on request, and coil is tagged with lot and specification details. If your purchase order requires a particular document type or standard, state it in the RFQ. Orbit's quality and certifications page covers ISO 9001, ISO 14001 and ISO 45001.

Common questions

Is a mill test certificate the same as a certificate of conformance?

Not necessarily. EN 10204 separates documents based on non-specific inspection from documents based on specific inspection, and only some document types report test results for the lot supplied. Name the document type you need on the purchase order.

Which standard should I put on the purchase order?

The one your design or local specification requires, for example ASTM B209 for sheet and plate to a US specification, or the relevant EN 485 part for European delivery. State the standard, the alloy and the temper together.

Can Orbit supply a test report for my order?

Test reports and ASTM or EN references are available on request. Tell us in the RFQ which documents you need and we will confirm what is provided for your order.

How do I know a certificate belongs to my coil?

Match the lot reference on the certificate to the tag on the coil. Orbit tags coil with lot and specification details so the two can be matched on arrival.

What if my line depends on a property the certificate does not report?

Raise it in the RFQ before production, so the testing and documentation can be confirmed for your order.

References

Orbit is an integrated aluminum coil manufacturer in Aqaba, Jordan, family owned and operating since 1976, with recycling, casting, rolling and coil coating on one site. We hold ISO 9001, ISO 14001 and ISO 45001. Anything not listed here is available on request.

Need documentation with your order?

Tell us which certificates, test reports and standards your purchase order requires. We respond to RFQs within one business day.

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The technical information in this article is prepared in good faith and verified against publicly available industry sources at the time of writing. Product specifications, applications and requirements can vary by project; always confirm current specifications directly with Orbit Aluminum Industries before purchasing or specifying. Orbit Aluminum Industries is not liable for decisions made or outcomes resulting from use of this content. See our Terms & Conditions.