Aviation CNC precision machining

Airframe brackets, actuator housings and engine mounts rarely sit in one plane. A rib runs at 30°, a boss points 15° off the bore axis, and the mounting feet are not parallel to either. On a 3-axis machine that means three or four fixtures, and every re-clamp adds stack-up error. On a simultaneous 5-axis center the tool tilts to reach the face while the table rotates once. One setup, one datum, fewer places for error to hide.

We run 16 simultaneous 5-axis machining centers and 12 four-axis mills in Dongguan and Singapore. The rotary table is Ø400 mm on the compact platforms, and the largest travel is 4,000 × 400 × 150 mm for long stringers. That range covers most bracket, housing and fitting work without splicing a part from two pieces.

Not every feature belongs on a 5-axis machine. A flat plate with a bolt pattern and two counterbores is faster and cheaper on a 3-axis mill. The choice is driven by how many faces need to be cut in one orientation, and whether a re-clamp would put a critical bore out of position.

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  Use 5-axis whenThree or more faces are machined and a bore-to-bore relationship matters.
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  Use 3-axis whenThe part is prismatic and one fixture holds every tolerance.
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  Use mill-turn whenA round body carries both turned diameters and milled flats.

Aviation parts are not cut from mild steel. Ti-6Al-4V (TC4) holds strength at temperature but conducts heat poorly, so the cutting edge absorbs it. Inconel is worse: it work-hardens under the tool and pushes back on every pass. Aluminium 7075 and 6061-T6 are the easy side of the shop, but 7075 still moves when thin walls are released from the block.

Each material gets its own parameters. For titanium we run lower surface speed, high-pressure coolant aimed at the contact zone, and a sharp uncoated or AlTiN-coated carbide tool. Depth of cut stays modest to keep the heat in the chip, not in the part. For Inconel we favor rigid setups, climb milling and a toolpath that never rubs the surface on a second pass. Rubbing is what kills the edge and burns the finish.

Magnesium AZ31B and AZ91D cut fast but need chip control and fire-safe handling. Beryllium copper machines well and is used where thermal or electrical conductivity is needed. We stock aluminium grades 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075, ADC12; stainless 303, 304, 316, 316L, 420, 430, 431, 440C, 17-4PH; and steel 1018, 1045, 4130, 4140, 4340.

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  Ti-6Al-4VLow speed, high coolant pressure, modest depth of cut.
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  InconelRigid setup, climb milling, no dwelling on the surface.
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  7075 aluminiumWatch thin-wall spring; rough, stress-relieve, then finish.
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  17-4PH stainlessMachine in the annealed condition, then age to hardness.

A tolerance on a drawing is a promise. Meeting it starts before the cut: material is checked on arrival, the machine is warmed and probed, and the first article is measured off the fixture. We hold ±0.005 mm (±0.0002 in) on critical features, and surface finish lands at Ra 0.2–0.8 μm on sealing faces, Ra 0.8–1.6 μm on general mating surfaces, and Ra 1.6–3.2 μm as-machined where nothing touches.

Temperature is the quiet variable. A 100 mm aluminium part grows about 0.0023 mm per degree Celsius. If the shop is 6 °C warmer than the inspection room, the part measures differently in each place. We keep the finishing and inspection areas close in temperature and let parts settle before final measurement. On long parts, we check straightness after stress relief rather than straight off the machine.

Thin walls are the other trap. A 1.5 mm rib can deflect under cutting force and spring back when the clamp is released. The fix is light finishing passes, support on both sides where possible, and roughing that leaves even stock. If a wall is thinner than 1 mm over a long span, we will say so at quote time rather than promise a number we cannot repeat.

Every part is inspected before it ships. Incoming material gets a check against the cert, in-process checks catch drift before the finish pass, and the final inspection measures the drawing dimensions on a CMM or a vision system. Reports are available on request, including dimensional results and material traceability.

Our quality system is certified to ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022. Those certificates matter less than the routine behind them. First-article inspection on a new part, SPC on a running order, and a non-conformance process that stops a bad lot instead of shipping it.

Uploads are secure and confidential. If your drawings carry export-control or proprietary markings, we can sign an NDA before you send anything. We do not share part geometry or customer names.

Machining is not always the cheapest path. If a housing is a hollow shell with uniform 2 mm walls and no tight bores, die casting or vacuum casting will make it faster and cheaper once volume justifies tooling. If the geometry is a lattice or an internal channel no tool can reach, metal 3D printing may win. We quote all three, so the recommendation is not tied to one process.

Aviation CNC precision machining makes sense when the part carries a tolerance that a casting cannot hold without a second op, when the material is a high-strength alloy that resists other processes, or when the quantity is low and tooling cost would dominate. From one prototype to 10,000+ parts, there is no minimum order quantity. A quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours.