Key takeaways
- Match the press range and circumscribing circle to your profile first.
- In-house finishing and machining mean fewer hand-offs and one accountable supplier.
- Ask for evidence: certificates, sample mill certs and inspection reports.
- A good DFM review on your drawing is the best test of engineering support.
- Put die ownership, MOQ, lead times and packaging in writing.
Choosing an extrusion supplier is a long-term decision: once your die sits in their plant, switching costs time and money. This checklist helps you compare suppliers on what actually matters.
1. Technical fit
- Press range and circumscribing circle. Can their presses run your profile’s size efficiently — not just at the edge of their capability?
- Alloys and tempers. Do they regularly extrude your alloy (6063, 6061, 6005A, 6082) and achieve your temper?
- Profile complexity. Have they made similar hollows, tolerances and wall thicknesses?
2. What is really in-house
Ask which steps happen in their own plant and which are subcontracted:
| Step | In-house? |
|---|---|
| Die design and correction | |
| Extrusion and aging | |
| Anodizing / powder coating | |
| CNC machining and fabrication | |
| Inspection and packing |
Every hand-off between companies is a place where tolerances drift, parts get damaged and schedules slip.
3. Quality evidence
- Certifications such as ISO 9001 — verify them with the issuing body.
- Material certificates with chemical composition per lot.
- Inspection reports — ask for a sample first-article or dimensional report.
- Process controls — hardness checks after aging, coating thickness measurement.
4. Engineering support
Send your drawing and see what comes back. A strong supplier will question tolerances, suggest radius or wall changes, and explain die implications. A quote with no questions at all is a warning sign.
5. Communication
- Response time and clarity in your language.
- A named engineer or project contact.
- Willingness to share photos and reports during production.
6. Commercial terms in writing
- Die cost, ownership and storage.
- MOQ per run and per finish/color.
- Sample and production lead times.
- Payment terms and Incoterms.
- Claims process for defects.
7. Packaging and export experience
Ask how profiles are protected, how containers are planned (6 m profiles need a 40-foot container), and which export documents are standard.
Red flags
- No questions about your drawing.
- Reluctance to show the plant, even by video.
- Certificates that cannot be verified.
- Prices far below the market with no explanation.
- Vague die ownership terms.
Start with a sample order
The best test is a small, real order: one die, samples, a dimensional report and a first production batch. Send us your drawing to start — or read how to prepare an RFQ.
Frequently asked questions
Should I choose an extruder or a trading company?
An extruder controls the process and can solve technical problems directly; a trading company can simplify sourcing across many parts. For custom profiles with tight requirements, working directly with the extruder usually gives better control.
How can I verify a supplier I cannot visit?
Request a live video tour of the press, finishing and inspection areas, sample documents (mill certificates, inspection reports), certificates you can verify with the issuing body, and references from customers in your market. Start with a sample order.
What documents should come with each shipment?
Commercial invoice, packing list, material (mill) certificates, inspection reports where specified, and a certificate of origin if required for customs.