Aviation CNC Machining: What to Check Before Releasing a Drawing

Flight and ground-support hardware make up most of the work: brackets, housings, fittings, bushings, actuator bodies, sensor mounts, and structural ribs. Parts are usually small to medium, run in low to mid volume, and judged on three things: dimensional accuracy, surface integrity, and documentation.

The material list is narrower than in general machining. Aluminum 6061-T6 and 7075 cover a large share of brackets and housings because they cut fast and hold tolerance well. Titanium Ti-6Al-4V (TC4) and 17-4PH stainless appear where strength or corrosion resistance matters more than cycle time. Inconel shows up in hot sections, and it is slow.

Not every part belongs here. Large thin-wall skins, long extrusions, and parts whose tolerance is driven by assembly rather than function may be cheaper as sheet metal or castings. A machined billet is the right answer when you need stiffness, tight interfaces, or low volume before tooling is justified.

A 3-axis machine moves in X, Y, and Z. Add two rotary axes and the tool can reach five faces of a part without releasing the clamp. That single-setup approach is what keeps hole patterns and mating faces in the same coordinate frame.

Every re-clamp adds stack-up error. On a bracket with a bolt circle on one face and a boss on another, two setups might add 0.02 mm of positional drift. One 5-axis setup removes that variable, and it also lets the tool stay normal to a contoured surface, so you get a consistent scallop height instead of a rubbed finish.

The trade-off is programming time and machine availability. Simple flat plates, slots, and drilled holes do not need five axes. Sending that work to a 3-axis machine is faster and cheaper. We route jobs by geometry, not by habit.

Our floor runs 16 simultaneous 5-axis machining centers, 12 four-axis mills, 27 three-axis machines, and 16 mill-turn centers. Maximum processing size is 4,000 mm, with a Ø400 mm rotary table for round parts that need milling and turning in one cycle.

Aluminum is forgiving. 6061-T6 machines clean, takes anodizing well, and holds ±0.005 mm on features that are not too thin. 7075 is stronger but gummier, so we slow the spindle and watch chip evacuation. Both are common in airframe brackets and equipment housings.

Titanium is where the process gets serious. TC4 (Ti-6Al-4V) has low thermal conductivity, so heat stays in the cutting zone. Tools wear fast and the part can spring back after the cut. We use lower surface speeds, higher coolant pressure, and lighter radial passes. Thin webs in titanium will deflect, so design them thicker first and let us tell you where they can be reduced.

Stainless 17-4PH and 316L are stable and corrosion resistant, and they take a good finish. Inconel and magnesium AZ31B sit at opposite ends: Inconel is abrasive and slow, magnesium is light and cuts quickly but needs care with chips. Tell us the alloy and temper on the drawing. The same part in 6061 and in TC4 is two different jobs.

Tolerance is a system, not a single number. We work to ±0.005 mm (±0.0002 in) on features that the setup and material support. A thin titanium wall or a deep small-diameter hole will not hold that, and it is better to say so early than to ship a part that measures borderline.

Surface finish options are Ra 0.2–0.8 μm for fine work, Ra 0.8–1.6 μm for most mating faces, and Ra 1.6–3.2 μm as-machined. Going finer usually means a second operation, so specify it only where a seal, bearing, or fatigue surface needs it.

Inspection covers raw material check, in-process monitoring, and final inspection, with 100% inspection before shipment. Reports are available on request. If your drawing calls out CMM data on specific features, flag them and we will plan the setup so those features are accessible to the probe.

Certifications on file: ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022. The information security certificate matters if you are sending controlled drawings. Uploads are treated as confidential, and an NDA is available on request.

Send a 3D model and a 2D drawing with the critical dimensions called out. We return a quotation and a free DFM analysis within 12 hours, and production can start within 24 hours after that. Parts ship in 3–5 days for most jobs.

The most common fixes we suggest: open up a deep pocket corner so a smaller tool can reach it, add a radius where a square internal corner is not functional, thicken a floor that would chatter, and move a tight tolerance off a face that will be used for clamping. None of these change function. They change cost and yield.

There is no minimum order quantity. One prototype and a 10,000-part run go through the same DFM review. Historical late-delivery probability is below 2%, which we track because aviation schedules do not absorb surprises well.