01How the process works
Billets are heated to around 450 to 500 °C and pushed through the die by a hydraulic press. The profile is cooled on the runout table, stretched to straighten it, cut to length and artificially aged (T5 or T6). Many profiles are then anodised or powder coated.
Dimensional tolerances, straightness and twist, surface quality and mechanical properties are the main acceptance criteria. Hollow profiles add the risk of weak seam welds formed inside porthole dies.
- Billet heating. Homogenised billets heated.
- Extrusion. Billet pressed through the die.
- Quench and stretch. Profile cooled and stretched straight.
- Cut and age. Cut to length and aged in ovens.
- Finishing. Machining, anodising or powder coating.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Die lines and pick-up | Die condition, billet quality | Visual |
| Blisters | Trapped gas, billet surface | Visual, after anodising |
| Dimensional and twist deviations | Die wear, stretching | Gauges, CMM, straightness |
| Low hardness | Ageing, quench rate | Webster or Brinell hardness |
| Weak seam welds | Porthole die, temperature | Expansion or bend tests |
| Coarse grain bands | Temperature, alloy | Macro etch |
03Where an inspector should look
01
Before production
- Die drawing and first profile approval
- Alloy and temper
- Surface class for visible faces
02
During production
- Billet and exit temperature
- Press speed
- Ageing oven charts
03
After production
- Profile dimensions and straightness
- Hardness per lot
- Surface inspection, coating thickness if finished
04Standards and references
EN 755 (extruded rod, tube and profiles), EN 12020 (precision profiles for 6060 and 6063), EN 573 alloy designation.
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.
05How we support buyers of aluminium extrusion parts
Independent Quality ControlIncoming, in-process and final quality control performed independently at the supplier, with measured results and clear acceptance decisions.
Supplier Inspection and Production SurveillanceSource and shop inspection during manufacturing: raw material, in-process and final inspection, and production surveillance.
Pre-Shipment InspectionFinal random or complete inspection of finished goods before shipment: quantity, conformity, workmanship, packing and marking.