Application of Aluminum Profiles in Aerospace

An aircraft structure is judged on stiffness per unit mass, fatigue life and how the part behaves after thousands of pressurization cycles. Aluminum answers those demands well when the alloy and temper are matched to the load path. The 2xxx and 7xxx families carry most primary structure because copper and zinc additions raise yield strength. The 6xxx family trades some strength for weldability and extrusion quality, so it lands in secondary frames, brackets and interior support.

Temper matters as much as chemistry. 7075-T6 reaches roughly 500 MPa tensile strength, but it is notch sensitive and does not weld. 6061-T6 sits near 310 MPa and welds cleanly, which is why seat tracks and equipment racks often use it. A profile drawn in 7075-T6 to save weight can cost more in machining and inspection than a slightly heavier 6061-T6 design that needs no special handling.

Corrosion resistance follows the same split. 7075 and 2024 need cladding, anodizing or a protective primer on exposed faces. 6061 and 5083 tolerate moisture and salt spray better in the as-machined state, which shortens finishing time on cabin and galley hardware.

Fatigue is the quiet constraint. Sharp internal corners on an extrusion die become stress risers in service. Designers who add a generous radii at the web-to-flange junction usually extend crack-initiation life without adding mass, and the die shop can hold that radius more consistently than a machined fillet.

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  Primary structure7075-T6 and 2024-T3 for high-load frames and fittings
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  Welded assemblies6061-T6 and 5083 where fusion welding is required
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  Interior and secondary6063-T5 for seat rails, trim and equipment mounting

A constant cross-section over a long length is the signal to extrude. Stringers, seat tracks, floor beams and equipment rails all share that trait. The die cost is recovered quickly because the mill pushes metal through in one pass instead of cutting 70–90% of a billet into chips. Wall thickness stays uniform, which helps control quench distortion after heat treatment.

Changing geometry along the length pushes the decision the other way. A fitting with bosses, pockets and angled lugs rarely justifies a complex die. Machining from 6061-T6 or 7075-T6 plate gives the designer freedom to add local thickness where the load path needs it, and revisions cost nothing beyond new toolpaths. For low-volume aerospace work, that flexibility usually outweighs the material savings of an extrusion.

The middle ground is a simple profile plus secondary machining. Buy a standard channel or angle, then mill the end details, drill the fastener pattern and face the mating surfaces on a 3-axis or 4-axis mill. This keeps die cost at zero and still avoids cutting the whole part from solid. We see this pattern often on brackets and clamps where the profile supplies the stiffness and the machining supplies the interface.

One more factor is traceability. Extruded stock arrives with a mill certificate tied to a heat number. That paper trail is straightforward to audit, and it satisfies the material verification steps most aerospace programs require before a part moves to assembly.

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  Choose extrusionConstant section, long length, high unit volume
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  Choose hog-outVariable section, low volume, frequent design changes
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  HybridStandard profile plus milled ends and drilled holes

Extruded stock carries mill tolerances that are looser than a finished machined surface. A profile may arrive within a few tenths of a millimeter on wall thickness and still need machining on the faces that mate with other parts. Designers should mark those faces clearly and leave stock for a cleanup cut. Holding ±0.005 mm on a machined pad is routine; expecting the same on an as-extruded web is not.

Straightness is the other recurring issue. Long profiles twist and bow slightly after quenching, and the amount grows with length. A 4,000 mm section that looks true on the bench can show measurable deviation once fixtured. If the drawing calls for a tight straightness band, plan a straightening or machining step, or split the part into shorter sections joined at a fitting.

Surface finish depends on the die and the alloy. 6063 extrudes to a smooth, bright surface that anodizes well, which is why interior profiles often skip additional finishing. 7075 tends to show more die lines and may need bead blasting before anodizing. For parts that will be inspected visually, specify the finish callout early so the shop can pick the right sequence.

Anodizing adds a thin oxide layer that changes dimensions by a few micrometers per surface. On a profile with tight bore or slot tolerances, that shift matters. Either mask the critical faces or account for the coating thickness in the pre-plate dimension. Hardcoat anodizing builds more thickness and should be treated the same way.

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  Machined facesCan hold ±0.005 mm with proper fixturing
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  As-extruded facesDimensional variation is larger; leave cleanup stock
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  AnodizingAdds micrometers per surface; mask critical features

Floor structure is a heavy user. Seat tracks, cross beams and floor panels rely on extruded sections that run the length of the cabin. These parts see repeated foot traffic and galley loads, so wear resistance and fastener pull-out strength drive the design. A hardcoat anodized 6061-T6 track handles that duty well and keeps weight low.

Wing and fuselage internal structure uses profiles as stringers and stiffeners. They carry bending loads along the skin and transfer them into frames and ribs. The cross-section is usually a blade, hat or J shape chosen for buckling resistance. Because these runs are long and the section is constant, extrusion is the natural route.

Ground support and test equipment is another category. Carts, fixture frames, test stands and handling rails are built from standard profiles because they need to be reconfigurable and cheap to modify. Strength requirements are lower than flight hardware, so 6063-T5 or 6061-T6 covers most cases, and the T-slot systems common in this space machine and assemble quickly.

Equipment racks and avionics bays sit between those extremes. They need stiffness, grounding paths and clean cable routing. An extruded frame with milled mounting faces gives all three, and the machined interfaces let us hold the flatness that circuit card guides require.

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  Cabin floorSeat tracks, beams, galley support rails
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  AirframeStringers, stiffeners, frame segments
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  Ground supportFixture frames, carts, test stands

We machine extruded and plate stock on 127 high-precision CNC machines, including 16 simultaneous 5-axis centers and 16 mill-turn centers. Maximum processing size reaches 4,000 mm, which covers most profile runs without splicing. For long parts we fixture on the rotary table and index between setups so the datum stays consistent from end to end.

Inspection follows the same sequence regardless of volume. Raw material is checked against the mill certificate, in-process dimensions are monitored during the run, and every part gets a final inspection before shipment. Reports are available on request. Tolerances down to ±0.005 mm and finishes from Ra 0.2–0.8 μm are achievable on machined faces when the drawing calls for them.

Finishing options include clear, color, hardcoat and conductive anodizing, plus plating, powder coating, bead blasting and laser marking. For aerospace profiles, anodizing and bead blasting are the most common requests because they address corrosion and surface appearance without adding much mass.

Quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours. There is no minimum order quantity, so a single prototype and a 10,000-part run follow the same process. Uploads are kept confidential and an NDA is available on request.

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  Capacity127 CNC machines, 16 five-axis centers, 4,000 mm max size
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  Quality100% inspection, ±0.005 mm, reports on request
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  Lead timeQuote in 12 hours, production in 24 hours, parts in 3–5 days