Machined aluminium parts start from one of two places: an extruded blank, where the section already puts metal where the part needs it, or a billet, where the shape is cut out of solid stock. The choice changes cost, rigidity and lead time more than the machining itself. At this plant extrusion and machining sit in the same building, so a part can be extruded, cut, machined to ±0.05 mm and anodized without leaving the site.
This page is about choosing the starting point and writing a drawing that can be machined economically. The product pages cover specific families: profiles, robotics parts and inverter housings.
| Starting point | Where it wins | Where it stops |
|---|---|---|
| Extruded blank | Long parts, constant section, features that run along the length; metal only where the design needs it; low cost per kilogram | Needs a die; section changes cost money; wall cannot go below 0.8 mm |
| Billet | Small quantities, pockets and steps in every direction, parts with no constant section | More material removed, longer cycle time, higher cost per part |
If the part is longer than it is wide, and most of its features run along one axis, extrusion is almost always the cheaper route. The die puts the wall, the ribs and the screw channels in place, and the machining is then limited to the ends, the holes and the pockets that cannot be extruded.
The limits are geometric. Wall thickness cannot go below 0.8 mm, the section has to fit a 540 mm circumscribed circle, and any change of section along the length has to be machined rather than extruded. A part that needs three different widths along its length is a billet job or a fabrication, not an extrusion.
Billet wins when the geometry is not constant: a housing with a pocket in the base, a bracket with steps on four faces, a prototype where no die exists yet. The material cost is higher because more of it leaves as chips, but there is no tooling and no die lead time, which matters for one-off and small-series parts.
The practical break point is quantity. Below a few hundred pieces, a billet part usually beats a new die; above that, the die amortises and the extruded blank wins on both material and cycle time. The exact crossover depends on the section and the machining time, which is why the drawing and the quantity are quoted together.
Machined features are held to ±0.05 mm at this plant, which covers bores, bearing seats, mating faces and hole patterns. Threads, counterbores and tapped holes are cut in the same setup where possible, because a second setup adds cost and stack-up.
Two rules save money. First, tolerance only the features that mate: a drawing where every dimension is ±0.05 mm is a drawing that will be quoted high and inspected slowly. Second, decide the finish before the machining sequence: anodizing builds 10–15 µm per face, so a bore that has to take a bearing is usually masked or machined after anodizing, and that decision belongs on the drawing.
6063 for parts machined from an extruded blank, 6061 where strength and machinability matter, 6082 where a European drawing specifies it, 6463 where the part will be bright anodized. Temper is normally T5 or T6, taken from the drawing; T4 is used where the part is formed after extrusion.
Individual 5xxx and 7xxx grades can be produced on request, and 6005A is available on request. Anything outside that list is confirmed against the die and the press before quoting, because not every alloy behaves the same way through a thin-wall die.
Prototypes can be machined from billet, or from an existing extrusion if the section is close enough, in quantities from one piece. Series parts are quoted per piece, with the extruded blank or billet shown separately so the cost is visible.
What changes between the two is inspection, not machining. A prototype is checked against the drawing; a series part is checked against a first-article report, with the critical dimensions measured on every batch. Asking for that report at the quotation stage is cheaper than asking for it after the first shipment.
Yes, and that is the normal route: the profile is extruded to the section, cut to length, then drilled, milled, tapped and anodized. Machining after extrusion is cheaper than machining the whole shape from billet whenever the section is constant.
No. Extrusion gives a constant section; anything that changes along the length, crosses the section or needs a precision bore is machined afterwards. The saving comes from starting with the right section, not from avoiding the machine.
±0.05 mm on machined features, checked against the drawing. Extruded dimensions follow GB/T 5237 high precision, and the two are inspected separately because they come from different processes.
Yes, from one piece, usually from billet or from an existing section. Prototypes are quoted separately from series parts because the setup is not amortised.
Yes, AA10 or AA15, in silver, champagne, bronze, black or gold. Tell us which faces must stay bare or masked, because anodizing changes bores and fits by 10–15 µm per face.
Related pages: CNC machining of aluminum profiles, machined aluminum parts for robotics, and machined housings for solar inverters. For the cast alternative, see extruded versus die-cast housings.
LinkedAlu extrudes in Foshan on 26 presses (500–5000 MT), 100,000 t/year since 2005, FOB Shenzhen or Guangzhou. Extruded profiles start at 500 kg per section; machined parts are quoted per piece.
3 profiles listed
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