01How a custom extrusion is developed
Every custom profile follows the same path from drawing to delivery. The early steps decide most of the cost and risk, which is why our engineers review the section before any steel is cut.
Drawing & DFM review
We check wall balance, radii, tongue ratios, tolerances and alloy choice, and suggest changes that make the die stronger and the profile cheaper to run.
Die design
Solid dies for open shapes; porthole (bridge) dies for hollows. The die is designed around your section, alloy and press.
Trial extrusion
First samples are extruded, aged and measured against your drawing. You receive a dimensional report with the samples.
Approval & production
After you sign off the samples, production runs to the approved drawing, aged to the specified temper and stretch-straightened.
Fabrication & finishing
Cut to length, CNC machined, anodized or powder coated — whatever turns the profile into your finished part.
Inspection & packing
Final inspection against the approved sample, then export packing labelled to your part numbers.
02Solid, semi-hollow and hollow profiles
Extrusions are grouped by how enclosed their voids are, because that determines the die type, the die cost and the design rules that apply.
| Type | What it means | Die | Typical examples |
|---|---|---|---|
| Solid | No enclosed or partly enclosed voids | Flat (solid) die | Angles, channels, heat sinks, LED channels, flat bars |
| Semi-hollow | A partly enclosed void with a narrow gap to the outside | Solid die with a supported tongue, or porthole die | T-slot profiles, lipped C-channels, clip-in sections |
| Hollow | One or more fully enclosed voids | Porthole (bridge) die — metal splits and re-welds in the die | Tubes, enclosures, window frames, multi-hollow crash rails |
Hollow profiles made on porthole dies contain longitudinal seam welds. They are sound for structural and architectural use; tell us if your application needs seamless tube.
03Design guidelines that lower cost and risk
These rules of thumb keep dies strong, presses fast and scrap low. When function requires breaking one, we will tell you what it does to cost and lead time.
- Balance wall thickness. Keep adjacent walls as uniform as practical — large jumps make metal flow unevenly and cause distortion.
- Radius every internal corner. Even 0.5 mm helps; larger radii improve die life, surface quality and fatigue strength.
- Watch deep, narrow channels. A high tongue ratio (void area against gap width) weakens the die tongue and may force a costlier hollow die.
- Keep the section compact. A smaller circumscribing circle fits smaller, faster presses and a cheaper die.
- Tolerance what matters. Apply tight tolerances only to functional features and define datums; everything else can follow the standard.
- Mark cosmetic faces. Tell us which surfaces are visible so die lines and handling marks are controlled where they matter.
- Design features in, not on. Screw ports, snap-fits, PCB guides and fins built into the section remove machining steps from every part.
Read the full aluminum extrusion design guide for worked examples.
04Choosing alloy and temper
| Alloy | Best for | Strength | Extrudability | Anodized finish |
|---|---|---|---|---|
| 6063 | Architectural, heat sinks, LED, enclosures, framing | Medium | Excellent | Excellent |
| 6061 | Structural and machined parts | High | Fair | Good |
| 7005 | Welded frames — bicycles, skates | High | Fair | Good |
| 7075 | Highest-strength machined parts | Very high | Difficult | Good (technical) |
Compare alloys side by side in our 6061 vs 6063 guide and temper guide.
05From extrusion to finished part
Most custom profiles need more than extrusion. Keeping these steps in-house removes hand-offs between suppliers and gives you one point of accountability.
Precision cutting
Saw cutting to length, including mitres and tight length tolerances for assembly.
CNC machining
Pockets, holes, threads, slots and faces machined after extrusion. More on fabrication.
Punching & drilling
High-volume holes and slots punched or drilled with fixtures for repeatability.
Bending
Profiles and tubes bent to radius where the section and temper allow.
Surface finishing
Assembly & packing
Sub-assembly, fastener insertion, kitting and labelled export packing.
06Quality you can verify
- Dimensional report on first samples against your drawing
- Billets cast in-house from primary aluminum; every melt verified on a SPECTROMAX spectrometer
- Material certificates with chemical composition per lot
- Hardness checks after aging to confirm temper
- Coating thickness measurements for anodized and powder-coated parts
- Final inspection against the approved sample before packing
- Tolerances and surface quality better than the GB/T high-precision grade
See our five-level quality control and certifications.
07What to send for a quote
The more of this you share, the faster and more accurate the quote. Missing something? Send what you have — we will ask.
- 2D drawing (PDF, DWG or DXF) with dimensions and tolerances
- 3D model (STEP) if machining is required
- Alloy and temper — or the load and finish requirements if undecided
- Cut length and length tolerance
- Annual volume and quantity per release
- Surface finish, color and cosmetic faces
- Machining, assembly and packaging requirements
- Destination port or delivery address
08Frequently asked questions
What is the minimum order for a custom aluminum extrusion?
Custom profiles are quoted by weight, and the minimum run is set by press setup and billet usage — typically a few hundred kilograms per profile across the industry. We confirm the minimum for your specific section in the quotation, and development batches can often be arranged for trials.
How much does an extrusion die cost?
Die cost depends on profile size, complexity and whether it is solid or hollow. For most small and medium profiles it is far lower than casting or injection-mold tooling, and it is a one-time charge itemized in the quote. Our guide to extrusion die cost and lead time explains the drivers.
How long does it take to get samples?
For a typical profile, die manufacture and the first trial extrusion take around two to three weeks across the industry; complex multi-hollow dies can take longer. Your quotation states our sample lead time for your section, and samples ship with a dimensional report.
Who owns the extrusion die?
A die paid for by a customer is made for that customer's profile and is not used for anyone else's orders. It is stored and maintained at the plant between runs; ownership and storage terms are stated in the quotation.
Can you copy an existing profile from a sample?
Yes. Send the physical sample, or a photo with key dimensions, and we will draw the section for your approval before any die is made.
Last updated September 17, 2026 · Reviewed by the CharMax Aluminum engineering team