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NADCAP and Turning: What the Accreditation Does and Does Not Cover
Buyers searching for a NADCAP turning shop need a careful answer up front: NADCAP does not accredit turning as a process. It accredits the special processes that often follow a turned part, such as heat treat, surface enhancement, and chemical processing, and that distinction is where most sourcing confusion on this combination begins. This page explains honestly how NADCAP relates to turning, when a turned aerospace part actually invokes NADCAP, what the audits check, and how to verify accreditation in eAuditNet without being misled.
NADCAPAS9100ISO 9001
The Honest Answer: NADCAP Does Not Accredit Turning
This is an uncommon combination, and it deserves a straight answer. NADCAP, run by the Performance Review Institute on behalf of the aerospace primes, accredits special processes, the steps where conformance cannot be fully verified by inspecting the finished part. Conventional machining, including turning, is normally treated as a verifiable process: you can measure the diameter, length, and finish after the cut, so it has not historically required NADCAP accreditation the way heat treat or anodize does.
There is a Conventional Machining as a Special Process (CMSP) audit criteria set that some primes invoke for specific machining work, but it is far less common than the classic special-process accreditations, and most turned aerospace parts do not require it. So if a supplier markets itself as a NADCAP turning shop, ask precisely what their NADCAP accreditation covers; it is almost always one of the downstream special processes, not the lathe work itself.
The practical takeaway: for turning quality you want AS9100 (or ISO 9001 for non-aerospace). For the special processes your turned part passes through afterward, you want NADCAP on those specific processes. The two answer different questions, and conflating them is the most common mistake on this combination.
When a Turned Part Actually Invokes NADCAP
A turned aerospace part triggers NADCAP through what happens after the lathe. If your turned 4340 steel shaft needs a stress-relief or hardening cycle, the heat treat processor must be NADCAP accredited for Heat Treating and meet AMS2750 pyrometry requirements. If the turned part needs cadmium or nickel plating, passivation, or anodize, the chemical processor must hold NADCAP Chemical Processing accreditation against specs like AMS2700 for passivation. If a fatigue-critical turned journal needs shot peen, that falls under NADCAP Surface Enhancement per AMS2430.
Nondestructive testing is another frequent tie-in: penetrant or magnetic-particle inspection of a turned part for cracks routes through NADCAP NDT accreditation. Even the chemistry verification or materials testing can fall under NADCAP Materials Testing Laboratories. The pattern is consistent: the turning is the verifiable shaping step, and NADCAP attaches to the special processes that finish, treat, or test the part where you cannot inspect quality into every unit.
So the right sourcing question is not whether the lathe is NADCAP accredited, but whether every special process on your drawing routes through a processor accredited for that exact process and specification. An AS9100 turning shop owns the flow-down and should maintain accredited processors on its approved-supplier list.
Frequently Asked Questions
Not for turning in the usual sense. NADCAP accredits special processes, meaning steps whose quality cannot be fully verified by inspecting the finished part, such as heat treating, chemical processing, surface enhancement, nondestructive testing, and welding. Conventional turning is normally a verifiable process because you can measure the resulting dimensions and finish, so it does not require NADCAP the way those special processes do. There is a Conventional Machining as a Special Process accreditation that certain primes invoke for specific machining, but it is uncommon and most turned aerospace parts never trigger it. So when a shop advertises NADCAP turning, the accreditation almost always covers a downstream special process the shop also performs, like in-house heat treat or NDT, rather than the lathe work. The correct framing is to require AS9100 for the turning quality system and NADCAP separately for each special process your part passes through. Always ask the supplier exactly which process and scope their NADCAP accreditation covers.
A turned part invokes NADCAP through its downstream special processes, not through the turning itself. If the drawing calls for heat treatment, the processor must hold NADCAP Heat Treating accreditation and meet AMS2750 pyrometry requirements. If it calls for plating, passivation, or anodize, you need a NADCAP Chemical Processing source, for example against AMS2700 for passivation. Shot peen on a fatigue-critical turned journal routes through NADCAP Surface Enhancement per AMS2430. Penetrant or magnetic-particle crack inspection routes through NADCAP NDT. So review your drawing for every callout that happens after the lathe and confirm each special process routes through a processor accredited for that exact process and specification. The turning supplier, if AS9100 certified, owns the flow-down and should keep accredited processors on its approved-supplier list. If your turned part is purely dimensional with no special process and no NDT, it likely needs no NADCAP source at all, only a competent AS9100 turning shop.
Use eAuditNet, the database maintained by the Performance Review Institute that lists NADCAP-accredited suppliers. Search the processor by name and confirm the accreditation is active and current. The most important step is to read the scope: NADCAP accreditation is process-specific, so a supplier accredited for Heat Treating is not thereby accredited for Chemical Processing or NDT. Match the listed accreditation to the exact special process and specification your drawing requires. Also confirm the accreditation belongs to the specific legal entity and site that will actually process your part, since a common trap is a blanket claim that really belongs to a sister facility or a single process. NADCAP runs a merit-based cycle, so accreditation intervals vary with performance, which makes checking the current status worthwhile. For a turned part, you would verify the turning shop's AS9100 separately, then verify each downstream special-process source in eAuditNet against the precise process and spec the part needs.
No, they serve different purposes and you typically need both in the supply chain. AS9100 is the aerospace quality management system standard, and for turning it governs the quality discipline of the machining operation: configuration control, first-article inspection, key-characteristic management, traceability, and corrective action on the lathe. NADCAP accredits the individual special processes a part passes through after machining, like heat treat, plating, and NDT, where quality cannot be inspected into every unit. A turned aerospace part is generally made by an AS9100 turning shop and then routed to NADCAP-accredited processors for any special processes. Neither replaces the other: AS9100 does not vouch for the technical conformance of a heat treat run, and NADCAP does not vouch for the dimensional control of the turning. Primes flow both down where applicable. So the correct sourcing posture for a turned aerospace component is AS9100 on the machining supplier plus NADCAP on every special-process source the drawing invokes, verified separately in OASIS and eAuditNet respectively.
Last updated: July 2026
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