AS9100D CNC Machining for Aerospace Parts

AS9100D is not a certificate on a wall. It sits on top of ISO 9001:2015 and adds clauses that touch every job ticket. Risk management, configuration control, product traceability, and counterfeit-part prevention are the four that change day-to-day work in the machine shop.

Traceability is the one buyers feel first. The material certificate has to follow the part, not the batch. When a 7075 plate is cut into twelve brackets, each bracket keeps a link back to the heat number and the mill certificate for as long as the program runs. That link is written on the traveler before the first cut, not reconstructed from a filing cabinet afterward.

Configuration control is the second. Every drawing revision gets a number, and the shop floor is locked to the released revision for that work order. A change from Rev C to Rev D triggers a new first-article inspection. We do not machine Rev D geometry against a Rev C setup sheet, even when the difference looks like one hole moved 0.3 mm.

Counterfeit prevention is quieter but just as real. Fasteners, raw stock, and any purchased item that reaches the part are checked against the approved supplier list. Material that arrives without a mill certificate, or with a certificate that does not match the heat number stamped on the bar, does not enter a job.

Risk management shows up as a short review at quoting. We flag thin walls, deep pockets, tight true-position callouts, and any feature that needs a custom fixture. That flag goes to the customer with the quote, so the risk is a conversation rather than a surprise on the inspection report.

A job starts with the customer's model and drawing. We run a DFM review within 12 hours of receiving the files, and it is free. The review looks at wall thickness, tool reach, datum strategy, and whether the tolerances on the drawing are achievable with the process we plan to use.

Setup comes next. For a bracket with features on five faces, that usually means one or two vise setups on a 5-axis center rather than four or five setups on a 3-axis machine. Fewer setups means fewer datum shifts, and datum shifts are where most position errors come from.

In-process inspection runs on the machine between operations. Critical diameters and hole positions are checked before the part leaves the fixture, so a drift is caught while there is still stock to correct it. The operator records the measurement on the traveler.

Final inspection is separate from the machine. We use coordinate measuring machines and, where the drawing calls for it, surface profilometers to confirm finish. Every part is inspected before shipment, and inspection reports are available on request. Our qualification rate across shipped parts is 99.99%.

Finishing and marking come last. Anodizing, plating, and passivation are handled as controlled steps with their own records. Laser marking for part numbers and lot codes holds a minimum character height of 1.5 mm so the mark stays readable after surface treatment.

Aluminum covers most airframe and housing work: 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, and 7075. The 2024 and 7075 grades cut well and hold a good strength-to-weight ratio, but they are less corrosion resistant than 6061, so they usually need anodizing or a protective finish.

Stainless and steel handle the higher-load parts. We run 303, 304, 316, 316L, 420, 430, 431, 440C, and 17-4PH (SUS630) stainless, plus 1018, 1045, 4130, 4140, 4340, A36, and tool steel. The 17-4PH grade is a common choice for bushings and fittings that need strength plus corrosion resistance.

Titanium and high-temperature alloys are slower to cut and priced accordingly. TA1, TA2, TC4 (Ti-6Al-4V), Inconel, and magnesium AZ31B or AZ91D are all in our material list. These alloys demand lower cutting speeds, more coolant, and sharper tooling, so plan for longer cycle times than the same geometry in aluminum.

Plastics and composites round out the list: ABS, PC, PMMA, POM, PA, PEEK, PP, HDPE, and carbon fiber. PEEK and carbon fiber are the two that most often appear in aerospace brackets and insulators, and both need sharp tooling and controlled feeds to avoid delamination or melting.

AS9100D CNC machining fits parts that need tight tolerances, documented material, and a clear inspection trail. Brackets, housings, bushings, ribs, fittings, and mounts all fall in that range. We handle runs from a single prototype to 10,000+ parts with no minimum order quantity.

Not every part belongs here. A large flat panel with a 2 mm thickness and a 1 meter span will deflect under its own weight during machining, so holding ±0.005 mm across the full face is unrealistic. Sheet metal fabrication is the better route for that geometry.

Parts that need a forged or cast internal grain structure should start as a forging or casting and come to us for finish machining. Cutting the whole shape from billet changes the grain flow and can cost more material than the part needs.

Tooling access sets another limit. A deep pocket with a 3 mm corner radius and a 40 mm depth needs a long, thin tool that will chatter. We will quote it, but we will also tell you the corner radius that makes the pocket stable.

Anything that cannot be inspected should not be quoted as a flight part. If a feature is buried and no probe or CMM stylus can reach it, we flag it during the DFM review and suggest a change to the design or the datum scheme.