MANUFACTURING / JAPAN SOURCING
Aluminum substitution: the alloy number is only the start
A quote for “6061” leaves the temper, product form and governing specification open. Compare the supplied material state and the properties your part needs before accepting an alternative.
Ask what is missing after “6061”
A buyer has a drawing that calls for a specified plate and receives a cheaper offer described only as “6061 aluminum”. That description does not tell the buyer whether the material is plate, extruded bar or another form, which temper is supplied, or which specification the seller will certify.
The Aluminum Extruders Council distinguishes alloy from temper and explains complete alloy-temper designations for extrusions.[1] The alloy number is a starting point for identification, not a complete substitution decision.
- 1Alloy identity and governing specification
- 2Temper and supplied product form
- 3Dimensions, required properties and evidence for this lot
A material comparison, not a statement that plate and extruded products are interchangeable. No design properties are assigned by this illustration.
Retain the temper and the product form
Write the complete requested designation, including temper, rather than copying the alloy number alone. Temper identifies a material condition associated with treatment; it is not simply another brand name for the alloy.[1]
UACJ’s extrusion page organizes its products using alloy, temper and properties.[2] Its published product table is useful for understanding what must be identified. Do not use those numbers as acceptance limits for a plate, another thickness or a different supply specification. Ask for the applicable requirements and the offered material’s evidence.
Build a comparison around the actual part
For the plate request in this example, keep the drawing revision, intended machining and required final condition beside the requested material. The supplier should identify every difference in its offer rather than answering only “equivalent”.
| Comparison item | State in the request | Obtain for the offer |
|---|---|---|
| Identity | State in the requestComplete alloy/temper and specification/version | Obtain for the offerExact designation and a list of deviations |
| Product form | State in the requestPlate, bar, extrusion or other required form | Obtain for the offerManufacturing form actually supplied |
| Dimensions and condition | State in the requestThickness/section, tolerances, finish and delivery state | Obtain for the offerApplicable dimensional requirements and processing included |
| Properties that matter | State in the requestRequired characteristics and relevant test basis | Obtain for the offerEvidence for the specified form, size and condition |
| Traceability | State in the requestRequired certificate and lot identification | Obtain for the offerDocument content and link to the delivered stock |
Check the state after your processing
If the purchased stock will be machined, formed, welded or heat-treated, identify which condition the finished-part requirements apply to. Ask the material supplier and responsible engineer which properties and dimensional risks need review after that processing.
For a machined plate component, discuss flatness and dimensional inspection in the required delivered or machined state, and what assumptions about stock removal or subsequent processing remain open. Do not infer a guarantee against distortion from a temper suffix alone. Higher catalogue strength is also not an automatic improvement if the application needs another balance of forming, corrosion behaviour or other properties.
Approval needs an explicit deviation decision
Request the certificate format before ordering. Ask whether its contents are lot-specific results, declared conformity or catalogue information, and how the document will be tied to the delivered stock. Those documents have different evidential value; agree what is required.
If an international designation is proposed, ask the responsible engineer to review the governing specification and relevant composition, condition and property requirements. A cross-reference of alloy names does not settle every product requirement. Retain the accepted deviations, decision owner and drawing/material revision. Until that review is complete, label the offer as an alternative under review.
Questions to send your supplier
Open supplier questions
Requested stock / part drawing revision: Complete alloy and temper: Governing specification and version: Product form, dimensions, tolerances and supply condition: Intended machining/forming/joining and final requirements: Please identify the exact offered designation and every deviation. Provide the applicable property basis and proposed certificate content, linked to the delivered lot. Please mark catalogue information separately from lot-specific evidence. Destination, quantity and timing: Alternative approval owner / open decisions:
Sources
- Aluminum Extruders Council — Alloys and tempers
Public explanation of extrusion alloy and temper designations. Used for the distinction, not international equivalence or numerical design allowables.
- UACJ — High-strength aluminum extrusions
Manufacturer product descriptions and alloy/temper/property table. Published values are not treated as acceptance limits for another product.