What buyers should verify first
A reliable decision starts with evidence that matches the drawing, production volume and business risk. Use the table below during RFQ review; replace assumptions with named documents, owners and acceptance criteria.
| Review area | What good control looks like | Buyer action |
|---|---|---|
| Purchase requirement | Exact grade, temper/condition and governing specification | PO and drawing |
| Certificate | Issuer, heat/lot and reported results | MTC or CoC |
| Receiving | Marking matches certificate and quantity | Incoming record |
| Production | Cut blanks retain lot identity | Traveler or label |
| Verification | Independent testing based on risk | PMI, hardness or lab test |
1. Write an unambiguous material callout
“Aluminum” or “stainless” is insufficient. State alloy, temper or condition, product form and specification revision where necessary.
For sourcing approval, convert this point into a written requirement: identify the responsible party, evidence to retain, acceptance rule and response when the rule is not met. This keeps a sample success from being mistaken for a capable production system.
2. Inspect the certificate fields
Check that units, test values, heat number, producer and specification make sense. A polished PDF with no lot connection is not traceability.
For sourcing approval, convert this point into a written requirement: identify the responsible party, evidence to retain, acceptance rule and response when the rule is not met. This keeps a sample success from being mistaken for a capable production system.
3. Protect identity after cutting
Bars and plates lose mill markings when sawn. Require a traveler or durable lot label that follows blanks, work-in-process, inspection and packing.
For sourcing approval, convert this point into a written requirement: identify the responsible party, evidence to retain, acceptance rule and response when the rule is not met. This keeps a sample success from being mistaken for a capable production system.
4. Use risk-based verification
For critical parts, define positive material identification, hardness, conductivity or third-party chemistry testing as appropriate to the alloy and risk.
For sourcing approval, convert this point into a written requirement: identify the responsible party, evidence to retain, acceptance rule and response when the rule is not met. This keeps a sample success from being mistaken for a capable production system.
5. Control substitutions
Require written approval before any equivalent grade, alternate temper, remelt source or material change is used.
For sourcing approval, convert this point into a written requirement: identify the responsible party, evidence to retain, acceptance rule and response when the rule is not met. This keeps a sample success from being mistaken for a capable production system.
Practical buyer scenario
For 7075-T6 structural brackets, the PO should identify alloy and temper, and the receiving record should tie the mill heat to the production lot. A generic “aluminum certificate” is not enough.
The useful output is a controlled plan, not a promise. Record the drawing revision, assumptions, open questions, required evidence and approval gate in the RFQ or purchase order. For critical applications, obtain engineering, quality and regulatory review appropriate to the product.
RFQ checklist
- Controlled 3D model and 2D drawing with matching revision
- Material grade, condition or temper, and any certificate requirement
- Quantity per release, annual demand and target delivery date
- Critical-to-quality characteristics and agreed measurement method
- Surface finish, cosmetic zones, masking and post-finish dimensions
- Packaging, labeling, Incoterm and destination
- First-article, sampling, traceability and corrective-action expectations
Frequently asked questions
Is an MTC always required?
It depends on the contract and risk. Traceability should be proportional to safety, regulation and cost of failure.
Can PMI identify every aluminum temper?
Not by chemistry alone; temper may require hardness, conductivity or documented heat-treatment evidence.
What if a supplier combines material lots?
Require separate identification and reporting, or prohibit mixed lots for the order.
Who should keep records?
Define retention period and retrieval time in the purchase agreement.
Sources and further reading
Technical note: Examples in this guide are planning guidance, not a universal manufacturing specification. Final capability, certification, tolerances, treatment and acceptance criteria must be confirmed for the exact drawing and contract.
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