An aluminium profile drawing is usually a single cross-section and a length. It travels well, and several Vietnamese extruders will quote it within days. The quotations then differ in ways that are hard to read — one per kilogram, one per metre, one with the die included, one with anodising “as standard” — and the first delivery shows why: the alloy is the one the plant runs every day, the visible face carries rack marks, and the machined holes were drilled after anodising and show bare metal.
Most of this is settled, or left open, before production starts. This article covers the five decisions a buyer of extruded profiles and extruded-and-machined parts should make before a Vietnamese extruder quotes: alloy and temper, the die, the tolerance standard, the surface finish, and the cutting and machining that turn a profile into a part. Pressure die castings are a different process with different risks, covered in aluminium die casting from Vietnam.
💬 Have an aluminium profile you want extruded, finished and cut in Vietnam? Send us the section drawing and the annual quantity and we will help you build an enquiry that several extruders can quote on the same basis.
1. Alloy and temper: name both, with the standard
An alloy number without a temper, or a temper without a standard, leaves the extruder to choose strength, finish quality and price for you — so state the alloy, the temper and the standard that defines them.
Most architectural and general-purpose profiles are extruded in the 6000 series. Within it, the softer alloys extrude easily, take a good anodised finish and suit thin, complex sections; the stronger alloys suit structural parts but extrude more slowly and finish less evenly. A plant that runs one alloy all day will quote that one unless the drawing says otherwise.
The temper matters as much as the alloy. Two common examples: T5 means cooled from the extrusion process and then artificially aged; T6 means solution heat-treated and then artificially aged. They give different mechanical properties from the same alloy.
| What to state | Example reference | Why it matters |
|---|---|---|
| Alloy designation | EN 573-3 (composition), or ASTM B221 / ANSI H35.1 in North America | Fixes the composition limits, not just a family name |
| Temper | EN 515:2017, or ANSI H35.1 | Decides the heat treatment and so the strength |
| Mechanical properties | EN 755-2:2025, or ASTM B221 | Gives the minimum tensile, proof and elongation values to test against |
| Test certificate | Type of certificate and tests per lot | Proves the shipped lot, not a typical value |
Order a lot certificate with chemical composition and tensile results, tied to the cast and extrusion lot. Which certificate types to ask for, and who issues them, is set out in quality documents to request from a Vietnamese parts supplier. Ask where the billet comes from as well: if origin matters for your import duty, the billet source becomes a question for origin and transshipment risk.
2. The die: what you pay for and what you can move
An extrusion die is cheap compared with a mould but is designed for one plant’s presses, so agree who designs it, how it is corrected, how its wear is handled and what happens to it if you move.
The die is a steel disc with the profile shape cut through it. A solid section passes through a flat die. A hollow section — a tube or a profile with closed chambers — needs a die in which the metal splits around supports and welds together again inside the die. Semi-hollow sections, with a nearly enclosed void, sit between the two. Hollow dies cost more and are more sensitive to alloy and speed.
Points to put in the enquiry:
- Die charge and what it covers. The die itself, the first trial and the samples sent to you. Ask what happens if the first trial misses the drawing.
- Who corrects the die. The die is designed by the extruder or its die maker, around its own press and container size. Corrections are normally theirs; changes you make to the drawing after approval are not.
- Wear and replacement. Dies wear and are periodically corrected or replaced. Agree who pays for a replacement die and whether its cost is amortised in the price per kilogram.
- Size limits. Every press has a maximum circumscribing circle — the smallest circle that encloses the section. Ask whether your section fits comfortably on the press the plant intends to use; a section at the press limit is harder to hold in tolerance.
- Moving the die. Because a die is built for a particular press, it often cannot simply be run elsewhere. If you think you may move production later, assume a new die and trials.
Ownership, marking and release terms belong in the tooling agreement; see tooling and mould ownership in Vietnam.
3. Tolerances: pick the standard before you draw tighter lines
Profile tolerances come from published tables, so name the tolerance standard on the drawing and mark only the few dimensions that genuinely need to be tighter.
Extruded profiles are not held like machined parts. Wall thickness, overall dimensions, angles, flatness, straightness and twist all have tolerance tables in the extrusion standards, and the tolerance depends on the alloy, the size of the dimension and whether it crosses a hollow.
The common references:
- EN 755-9:2016 — tolerances on dimensions and form for general extruded profiles.
- EN 12020-2:2022 — closer tolerances for precision profiles in EN AW-6060 and EN AW-6063, mainly for architectural use, with stricter requirements on visible surfaces.
- ANSI H35.2 (2024 edition, with a metric version H35.2M) — the dimensional tolerance standard used for aluminium mill products in North America.
- JIS H 4100:2022 — extruded profiles under the Japanese standard, which Japanese drawings often cite.
Name one. If the drawing names none, the extruder applies the standard it knows and both sides think they agreed. Then mark the dimensions that control fit or assembly and give them their own tolerance; a tolerance tighter than the table may need a slower speed, a more expensive die or machining afterwards, and the quotation should show which.
Mark the visible faces on the drawing as well. They decide how the section is supported on the run-out table, where contact marks are allowed and which faces must be protected by film.
💬 Not sure whether your profile belongs under the general or the precision tolerance tables? We can review the section with you before it goes to quotation, as part of sourcing from Vietnam. Send us the drawing.
4. Surface finish: anodising, powder coating and where the marks go
The finish is often done by a different line or a different company from the extrusion, so specify it with its own standard, colour reference and test, and say where jig marks are allowed.
Anodising and organic coating are the two common finishes. Each has its own specification method:
| Anodising | Powder coating | |
|---|---|---|
| Specification | ISO 7599:2018, the method for specifying decorative and protective anodic coatings | EN 12206-1:2021, for thermosetting powder coatings on architectural aluminium |
| What to state | Coating thickness class, colour, sealing, appearance | Powder type, colour code, gloss, film thickness |
| Typical checks | Thickness by eddy current (ISO 2360); sealing quality by admittance (ISO 2931:2017) | Film thickness, adhesion, gloss, appearance |
| Colour control | Light and dark limit samples; anodised colour varies with alloy and lot | Colour standard and gloss level |
| Out of scope | Hard anodising is specified separately, under ISO 10074 | Liquid paint has its own specifications |
Three points cause most finish disputes:
- Rack or jig marks. Profiles are held by contacts during anodising or by hooks during coating, and the contact point stays bare or marked. State where marks are allowed — usually on ends that will be cut or on hidden faces.
- Colour range. Anodised colour shifts with alloy composition and from lot to lot. Agree a pair of physical limit samples, light and dark, rather than a single colour target.
- Order of operations. Cutting, drilling or punching after anodising exposes bare aluminium at the cut. Decide which faces and holes may be bare, or require machining before finishing — and check that the finisher’s jigs can hold the part once it has been machined.
Ask whether the finish is done in house or by another company. If it is outsourced, the drawing, the visible-face marking and the limit samples must reach the finisher, and the quotation should say who answers for a finish defect found after machining.
5. Cutting, machining and packing: from profile to part
Many buyers need a finished component rather than a length of profile, so list every operation after extrusion, who does it and in what order, and pack for the humidity of a sea voyage.
Typical secondary work on profiles includes cutting to length, end milling, drilling and tapping, punching, bending, thermal-break assembly and fitting accessories. List each one with its sequence and whether it is in house or outsourced, the same way you would for a casting. Drawing practice for the machined features — datums, general tolerances, threads — is covered in CNC machining in Vietnam.
For cut lengths, state the length tolerance, the squareness of the cut and the deburring required. For the price basis, ask whether the quotation is per kilogram, per metre or per piece. A per-kilogram price is calculated on a weight per metre; ask for the theoretical weight behind it, how the actual weight is invoiced and who pays for the end cuts and the scrap from cutting. Then put the quotations on one sheet with comparing Vietnamese supplier quotations.
Packing matters more than it looks. Aluminium shipped by sea can develop white surface corrosion or water staining if moisture condenses between tightly packed profiles. Agree:
- Protective film on visible faces, applied after finishing, and how long it may stay on before removal.
- Interleaving between finished profiles, so faces do not rub.
- Bundles or crates with support along the length, sized to the container, and end protection.
- Moisture control — dry packing and desiccant where the voyage is long.
- Labels on every bundle with part number, drawing revision, alloy and temper, finish, lot and length.
Inspection before loading — dimensions, finish against the limit samples, coating thickness readings, counting and packing — can then be written into pre-shipment inspection and AQL.
The enquiry checklist for an aluminium profile
Extrusion quotations become comparable when every extruder works from the same alloy, temper, tolerance standard, finish specification and list of secondary operations.
- Section drawing with visible faces marked, critical dimensions and the tolerance standard.
- Alloy and temper, with the standard that defines them, and the lot certificate required.
- Die: charge, trials, correction, wear and replacement.
- Finish: anodising or powder coating, standard, thickness, colour reference and limit samples, location of jig marks.
- Secondary operations: each one, in sequence, in house or outsourced.
- Cut length and tolerance, price basis and theoretical weight per metre.
- Packing method and labelling.
- Annual quantity, typical order and call-off pattern.
For plastic profiles extruded in Vietnam, the equivalent points are in plastic extrusion in Vietnam.
💬 For each project we find, vet and manage the Vietnamese extruder and finisher that fit the profile. Tell us about yours and we will tell you what we would ask the plants first.
Frequently asked questions
1. Do I need to name a temper if I have already named the alloy?
Yes. The same alloy in different tempers gives different strength. Name the temper, the standard that defines it, and ask for a lot certificate with tensile results.
2. If I pay for the die, can I take it to another extruder?
You can take it, but it may not run there without changes, because a die is built around a particular press. If you expect to move or dual-source, budget for a new die and trials at the second plant, and write ownership terms in the tooling agreement.
3. Why does anodised colour vary between deliveries?
Anodised colour depends on alloy composition, surface condition and process, and it varies naturally from lot to lot. Approve a light and a dark limit sample and judge each lot against the pair, rather than against a single colour.
4. Should holes be drilled before or after anodising?
It depends on whether a bare edge inside the hole matters. Drilling after anodising leaves bare metal; machining before means the finisher must be able to hang the machined part. Decide face by face and write it on the drawing.
5. How should I compare a per-kilogram quotation with a per-metre one?
Ask the per-kilogram supplier for the theoretical weight per metre and how actual weight is invoiced, then convert both to the same unit. Check what each includes — die, finish, cutting, scrap — before judging the price.
Sources: EN 573-3; EN 515:2017; EN 755-2:2025; EN 755-9:2016; EN 12020-2:2022; ASTM B221; ANSI H35.2 (2024); JIS H 4100:2022; ISO 7599:2018; ISO 10074; ISO 2360; ISO 2931:2017; EN 12206-1:2021. Checked on 19 October 2026.
More industrial sourcing guides: Plastic Extrusion in Vietnam: Dies, Dimensions and Regrind · Steel Fabrication in Vietnam: Welding, Paint and Shipping Size · Forgings From Vietnam: Process, Heat Treatment and Inspection. All guides by category are on the industrial sourcing page.